HK1237115A1 - Systems and methods for forming and maintaining a high performance frc - Google Patents

Description

System and method for forming and maintaining high performance FRC

The present application is a divisional application of patent application No. 201280055842.6, filed 2012, 11/14, entitled "system and method for creating and maintaining a high performance FRC".

Cross Reference to Related Applications

The present application claims the benefit of U.S. provisional application No. 61/559,154, filed on day 4, 11/2011, and the benefit of U.S. provisional application No. 61/559,721, filed on day 15, 11/2011, which are all incorporated herein by reference.

Technical Field

Embodiments described herein relate generally to magnetic plasma confinement systems and, more particularly, to systems and methods that facilitate forming and maintaining field inversion configurations with superior stability and particle, energy, and flux confinement.

Background

This configuration is attractive for its simple geometry, ease of construction and maintenance, a naturally unconstrained divertor to facilitate energy extraction and ash removal, and a very high β (β is the mean plasma pressure and f.f.Ratio of average magnetic field pressure within the RC), i.e., high power density, the high β property facilitates economic operation and use of advanced neutron-free fuels such as D-He³And p-B¹¹。

Conventional methods of forming FRC use field inversionθPinch technology, generating a hot high-density plasma (see a.l. Hoffman and j.t. slow, nuclear Fusion 33, 27 (1993)). One variant thereof is a translational-trapping process, in whichθThe plasma formed in the pinched "source" exits almost immediately from one end into the confinement chamber. The translated plasma clusters are then trapped between two strong mirrors at the ends of the chamber (see, e.g., h. Himura, s.okada, s. Sugimoto, and s. Goto, phys. plasma 2, 191 (1995)). Once in the confinement chamber, various heating and current driven methods may be employed, such as beam ejection (neutral or neutralized), rotating magnetic field, RF or ohmic heating, and the like. This source separation and containment function provides key engineering advantages for possible future fusion reactors. FRC has proven to be extremely robust, adaptive to dynamic formation, translation and violent capture events. Furthermore, they exhibit a tendency to assume a preferred plasma state (see, for example, h.y. Guo, a.l. Hoffman, k.e. Miller and l.c. steinhauer, phys. rev. lett. 92, 2454001 (2004)). Significant progress has been made in the past decades in the development of other FRC forming methods: spheromaks with helicity in opposite directions were incorporated (see, e.g., y. Ono, m.inomoto, y. Ueda, t. Matsuyama and t. Okazaki, nuclear. Fusion 39, 2001 (1999)) and also provided additional stability by driving current with a Rotating Magnetic Field (RMF) (see, e.g., i.r. Jones, phys. plasma 6, 1950 (1999)).

Recently, the long-term previously proposed collision-merging technique has been developed significantly further (see, e.g., d. r. wells, phys. Fluids 9, 1010 (1966)): two separate theta pinches at opposite ends of the confinement chamber simultaneously generate two plasma clusters and accelerate the plasma clusters toward each other at high speed; they then collide at the center of the confinement chamber and merge to form a composite FRC. In the construction and successful operation of one of the largest FRC experiments to date, a conventional collision-merge approach was shown to produce stable, long-lived, high-flux, high-temperature FRC (see, e.g., m. Binderbauer, h.y. Guo, m. Tuszewski et al, phys. rev. lett. 105, 045003 (2010)).

The FRC includes a torus of closed field lines inside the separatrix and an annular rim layer on the open field lines near the outside of the separatrix. The edge layers combine/merge into a jet that exceeds the FRC length, providing a natural divertor. The FRC topology conforms to the topology of the field-reversed mirror plasma. However, the significant difference is that the FRC plasma has a β of about 10. The intrinsic low internal magnetic field provides some of the original moving particle population, i.e., particles with a large larmor radius (larmor radii) compared to the small radius of the FRC. It is these strong kinetic effects that appear to at least partially contribute/contribute to the overall stability of past and present FRCs, such as those produced in collision-merge experiments.

Typical past FRC experiments have been subject to convective losses, where energy constraints are largely determined by particle transport. The particles diffuse out of the interface volume mainly in the radial direction and are then lost in the edge layer in the axial direction. Therefore, the FRC constraints depend on the characteristics of both the closed field line and open field line regions. The time of diffusion of particles from the interface is scaled to（a~r_s/4, wherein r_sIs the central interface radius) andis a characteristic FRC diffusivity, such asWhere ρ is_ieRepresents the ion radius of gyration and is evaluated by an externally applied magnetic field. Edge layer particle confinement timeIs the substantially axial transit time in past FRC experiments. At steady state, the balance between radial particle loss and axial particle loss yields the interface density gradient length. For past FRCs with significant density at the interface, the FRC particle constraint time scales as(see, for example, M. TUSZEWSKI, "Field reversed controls," Nucl. Fusion 28, 2033 (1988)).

Another drawback of existing FRC system designs is the need to use external multipoles to control rotational instabilities, such as fast-growing n =2 switching instabilities. In this way, the typical externally applied quadrupole field provides the required magnetic recovery pressure to dampen/suppress the development of these unstable modes. While this technique is adequate for stability control of thermal bulk plasma (thermal bulk plasma), it presents a serious problem for more kinetic energy FRC or advanced hybrid FRC, where high kinetic energy large orbital particle populations are combined with typical thermal plasma. In these systems, distortion of the axisymmetric magnetic field due to such a multipole field leads to significant rapid particle loss via collisionless random diffusion, with the result that the regular conservation of angular momentum is lost. It is therefore important that the novel solution to provide stability control without promoting any particle diffusion takes advantage of the potential for higher performance of these advanced FRC concepts that have never been explored before.

In view of the foregoing, it is therefore desirable to improve the constraints and stability of FRCs in order to use steady state FRCs as a way for a wide variety of applications, from compact neutron sources (for medical isotope production and nuclear waste remediation) to bulk separation and enrichment systems, and reactor cores for gathering light nuclei for future energy generation, and the like.

Disclosure of Invention

Embodiments of the invention provided herein are directed to systems and methods that facilitate the creation and maintenance of novel high performance Field Reversed Configurations (FRCs). In accordance with this novel high performance FRC paradigm, the system of the present invention combines a number of novel concepts and means to significantly improve the particle, energy, and flux constraints of FRCs, as well as provide stability control without producing undesirable side effects.

An FRC system provided herein includes a central containment vessel surrounded by two diametrically opposed opposing field-theta-pinch forming sections and two divertor chambers beyond the two forming sections to control neutral particle density and impurity contamination. The magnetic system includes: a series of quasi-dc coils located at axial positions along components of the FRC system; a collimating flow mirror coil between either end of the confinement chamber and the adjacent forming section; and a mirror plug comprising a compact quasi-dc mirror coil between each of the formation sections and the divertor, the compact quasi-dc mirror coil generating an additional guiding field to focus the magnetic flux surface toward the divertor. The forming section includes a modular pulsed power forming system that enables FRC to be formed in situ and then accelerated and jetted (= static formation) or simultaneously formed and accelerated (= dynamic formation).

The FRC system includes a neutral atom beam injector and a pellet (pellet) injector. A gettering system may also be included, as well as an axial plasma gun. A bias electrode is also provided for electrically biasing the open flux surface.

The systems, methods, features and advantages of the invention will be or will become apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional methods, features and advantages be included within this description, be within the scope of the invention, and be protected by the accompanying claims. It is also intended that the invention not be limited to the details of the example embodiments required.

Drawings

The accompanying drawings, which are included as part of the present specification, illustrate the presently preferred embodiments of the invention, and together with the general description given above and the detailed description of the preferred embodiments given below serve to explain and teach the principles of the invention.

Fig. 1 illustrates particle confinement in the FRC system of the present invention in the case of a high performance FRC protocol (HPC) as compared to the case of a conventional FRC protocol (CR) and as compared to the case of other conventional FRC experiments.

Fig. 2 shows the components of the FRC system of the present invention and the magnetic topology of the FRC that may be produced in the FRC system of the present invention.

Fig. 3 shows the basic layout of the FRC system of the present invention as viewed from the top, including the preferred arrangement of neutral beams, electrodes, plasma guns, mirror plugs and pellet injectors.

Fig. 4 shows a schematic diagram of the components of a pulsed power system for forming a section.

Fig. 5 shows an isometric view of an individual pulse power forming sled (ski).

Figure 6 shows an isometric view of the forming tube assembly.

FIG. 7 shows a partial cross-sectional isometric view of the neutral beam system and critical components.

Fig. 8 shows an isometric view of a neutral beam arrangement on a confinement chamber.

Fig. 9 shows a partial cross-sectional isometric view of a preferred arrangement of the Ti and Li gettering system.

FIG. 10 shows a partial cross-sectional isometric view of a plasma gun installed in a divertor chamber. Associated magnetic mirror plugs and divertor electrode assemblies are also shown.

Figure 11 shows a preferred layout of annular biasing electrodes at the axial ends of the confinement chamber.

Fig. 12 shows the evolution of the repulsive flux radius in an FRC system obtained from a series of external diamagnetic coils at two field reversal θ pinch forming sections and a magnetic probe embedded within a central metallic confinement chamber. Time is measured from the instant the sync field in the forming source reverses and gives the distance z relative to the axial midplane of the machine.

Fig. 13 (a) through 13 (d) show representative non-HPF, non-sustained discharge data from the FRC system of the present invention. Shows (a) the repulsive flux radius at the midplane as a function of time; (b) from the midplane CO₂6 chord-integrated density (6 chords of line-integrated density) of the interferometer; (c) from CO₂A density radial distribution of an Abel inverse transform of the interferometer data; and (d) total plasma temperature from pressure equalization.

Fig. 14 shows the repulsive flux axial profile at selected times for the same discharge of the FRC system of the present invention shown in fig. 13.

Fig. 15 shows an isometric view of a saddle coil mounted outside of a confinement chamber.

Fig. 16 shows the correlation between FRC lifetime and pulse length of injected neutral beam. As shown, longer beam pulses produce a longer lifetime FRC.

Fig. 17 illustrates the individual and combined effects of different components of an FRC system on FRC performance and achievement of HPF solutions.

Fig. 18 (a) to 18 (d) show data from representative HPFs, non-sustained discharges on the FRC system of the present invention. Shows (a) the repulsive flux radius at the midplane as a function of time; (b) from the midplane CO₂Density of 6 chord line integrals of the interferometer; (c) from CO₂A density radial distribution of an Abel inverse transform of the interferometer data; and (d) total plasma temperature from pressure equalization.

FIG. 19 shows as electricitySub-temperature (T)_e) Flux constraints of the function. Which represents a graphical representation of a newly established good scaling scheme for HPF discharge.

It should be noted that the figures are not necessarily to scale and that elements of similar structure or function are generally represented by like reference numerals for illustrative purposes throughout the figures. It should also be noted that the figures are only intended to facilitate the description of the various embodiments described herein. The drawings do not necessarily depict every aspect of the teachings disclosed herein and do not limit the scope of the claims.

Detailed Description

Embodiments of the invention provided herein are directed to systems and methods that facilitate forming and maintaining a high performance Field Reversed Configuration (FRC) that has superior stability and superior particle, energy, and flux constraints compared to conventional FRCs. Various auxiliary systems and modes of operation have been investigated to assess whether a good constraint condition exists in the FRC. These efforts have led to breakthrough discovery and development of the high performance FRC paradigm described herein. In accordance with this new paradigm, the system and method of the present invention combines a number of novel concepts and approaches to significantly improve FRC constraints (as shown in fig. 1) and provide stability control without adverse side effects. As discussed in more detail below, fig. 1 depicts a comparison of particle constraints in an FRC system 10 (see fig. 2 and 3) described below operating according to a high performance FRC scheme (HPF) for forming and maintaining an FRC versus operating according to a conventional scheme CR for forming and maintaining an FRC, and versus particle constraints according to a conventional scheme used in other experiments for forming and maintaining an FRC. The present disclosure will outline and detail the innovative individual components and methods of FRC system 10, as well as their collective effects.

Description of FRC System

Vacuum system

Fig. 2 and 3 depict schematic diagrams of the FRC system 10 of the present invention. The FRC system 100 includes a central containment vessel 100, the central containment vessel 100 surrounded by two diametrically opposed opposing field-opposing pinch forming sections 200 and two divertor chambers 300 beyond the forming sections 200 to control neutral density and impurity contamination. The FRC system 10 of the present invention is built to accommodate ultra-high vacuum and operates at a typical base pressure of 10 "8 torr. Such vacuum pressures require careful initial surface conditioning, such as physical and chemical cleaning, with double-pumped mating flanges between mating parts, metal O-rings, high purity inner walls, and all parts prior to assembly, followed by 24 hours 250 ℃ vacuum bake and hydrogen glow discharge cleaning.

The reverse field theta pinch forming section 200 is a standard Field Reverse Theta Pinch (FRTP), but with an advanced pulse power forming system (see fig. 4-6) discussed in detail below. Each forming section 200 is formed from a standard opaque industrial grade quartz tube featuring an ultra pure quartz liner with 2 millimeters. The confinement chamber 100 is made of stainless steel to allow for a number of radial and tangential ports; it also serves as a flux holder for the experimental timescales described below and limits rapid magnetic transients. A set of dry scroll roughing pumps, turbo molecular pumps and cryopumps are utilized to create and maintain a vacuum within the FRC system 10.

Magnetic system

A magnetic system 400 is shown in fig. 2 and 3. FRC magnetic flux and isopycnic lines (as a function of radial and axial coordinates) and other features related to the FRC450 producible by the FRC system 10 are shown in fig. 2. These isodensity lines were obtained by 2-D resistive hall-MHD numerical simulation using code developed to simulate a system and method corresponding to the FRC system 10 and consistent with measured experimental data. As seen in fig. 2, the FRC450 includes an annular ring of closed field lines at an interior 453 of the FRC450 inside the separatrix 451 and an annular ring of edge layers 456 on open field lines 452 slightly outside the separatrix 451. The edge layers 456 combine to provide a jet 454 that exceeds the FRC length, providing a natural divertor.

The main magnet system 410 includes a series of quasi-dc coils 412, 414, and 416 at specific axial locations along the components of the FRC system 10, i.e., along the confinement chamber 100, the formation section 200, and the divertor 300. The quasi-dc coils 412, 414, and 416 are powered by a quasi-dc switching power supply and generate a substantially magnetic bias field of about 0.1T in the confinement chamber 100, the formation section 200, and the divertor 300. In addition to the quasi-dc coils 412, 414 and 416, the main magnet system 410 includes a quasi-dc mirror coil 420 (powered by a switching power supply) between either end of the confinement chamber 100 and the adjacent formation section 200. The quasi-dc mirror coils 420 provide a magnetic mirror ratio of up to 5 and can be independently energized for balanced shaping control. In addition, a mirror plug 440 is positioned between each of the formation section 200 and the divertor 300. The mirror plug 440 includes a compact quasi-dc mirror coil 430 and a mirror plug coil 444. The quasi-dc mirror coil 430 includes three coils 432, 434, and 436 (powered by a switching power supply) that generate additional steering fields to focus the magnetic flux surface 455 toward the small diameter via 442 through the mirror plug coil 444. A mirror plug coil 444 wound around the small diameter via 442 and powered by an LC pulse power circuit generates a strong mirror field of up to 4T. The purpose of this entire coil arrangement is to closely bunch and direct the magnetic flux surface 455 and end-flowing plasma jet 454 into the remote chamber 310 of the divertor 300. Finally, a set of saddle coil "antennas" 460 (see fig. 15) are located outside the confinement chamber 100, two on each side of the midplane, and fed with a dc power supply. The saddle coil antenna 460 may be configured to provide a quasi-static magnetic dipole or quadrupole field of about 0.01T for controlling rotational instability and/or electronic current control. The saddle coil antenna 460 can flexibly provide a magnetic field that is symmetric or asymmetric about the machine midplane, depending on the direction of the applied current.

Pulse power forming system

The pulse power formation system 210 operates according to a modified theta pinch principle. There are two systems each supplying power to one of the forming sections 200. Fig. 4-6 illustrate the main building blocks and arrangements of the forming system 210. The forming system 210 includes a modular pulse power arrangement that includes individual cells (= sleds) 220 that each energize a subset of coils 232 that are wound around a ribbon assembly 230 (= ribbon) that forms a quartz tube 240. Each sled 220 includes a capacitor 221, an inductor 223, a fast high current switch 225 and associated flip-flop 222 and phagocytizer (dump) circuit 224. In summary, each forming system 210 stores between 350-400KJ of capacitive energy, which provides up to 35GW of power to form and accelerate FRC. Coordinated operation of these components is achieved via prior art trigger and control systems 222 and 224, which prior art trigger and control systems 222 and 224 allow synchronized timing between the forming systems 210 on each forming section 200 and minimize switching jitter to tens of nanoseconds. The advantage of this modular design is its flexible operation: FRCs can be formed in situ and then accelerated and sprayed (= static formation) or formed and accelerated simultaneously (= dynamic formation).

Neutral beam injector

The neutral atom beam is deployed on FRC system 10 to provide heating and current drive as well as to create a fast particle pressure. As shown in fig. 3 and 8, the individual beam lines comprising neutral atom beam injector systems 610 and 640 are located around the central confinement chamber 100 and inject fast particles tangentially to the FRC plasma (and perpendicular to the axis of the confinement chamber 100), with certain impact parameters such that the target trapping region is located within the separatrix 451 (see fig. 2). Each injector system 610 and 640 is capable of projecting up to 1MW of neutral beam power into the FRC plasma with particle energies between 20 and 40 KeV. The systems 610 and 640 are based on positive ion multi-aperture extraction sources and utilize geometric focusing, inertial cooling, and differential pumping of ion extraction grids. The main difference between systems 610 and 640, other than the use of different plasma sources, is that they are physically designed to meet their respective installation locations, resulting in side and top spray capabilities. Typical components of these neutral beam injectors are specifically shown in fig. 7 for the side injector system 610. As shown in fig. 7, each individual neutral beam system 610 includes an RF plasma source 612 at the input end (which is replaced by an arc source in system 640) and a magnetic shield 614 covers that end. The ion source and acceleration grid 616 is coupled to the plasma source 612 and a gate valve 620 is positioned between the ion source and acceleration grid 616 and the neutralizer 622. The deflecting magnet 624 and the ion phagocytizer 628 are located between the neutralizer 622 and the aiming device 630 at the exit end. The cooling system includes two cryocoolers 634, two cryopanels 636, and an LN2 hood 638. This flexible design allows operation over a wide range of FRC parameters.

Pellet injector

To provide a means of injecting new particles and to better control FRC particle inventory, a 12-barrel Pellet injector 700 (see, e.g., I.Vinyar et al, "Pellet injection Developed at PELIN for JET, TAE, and HL-2A," Proceedings of the 26th Fusion Science and Technology Symposium, 09/27to 10/01(2010) at 9, 10, 1, 2010) is utilized on the FRC system 10. FIG. 3 shows the layout of the Pellet injector 700 on the FRC system 10. cylindrical pellets (D-1 mm, L-1-2 mm) are injected into the FRC at a velocity in the 150- "250 km/s range. each individual Pellet contains about 5 × 10 to 10¹⁹Hydrogen atoms, which correspond to the inventory of FRC particles.

Gettering system

Neutral halo gases (halo gas) are well known to be a serious problem in all confinement systems. The charge exchange and recycling (release of cold foreign material from the walls) process can have a devastating effect on energy and particle confinement. Furthermore, any significant density of neutral gas at or near the edge will result in a loss of lifetime of large orbital (energetic) particles (large orbital refers to particles having an orbit with FRC topology scale or at least having an orbit radius much larger than the characteristic magnetic field gradient length scale) that promote ejection or at least severely curtailment the lifetime of the ejected large orbital (energetic) particles, which is detrimental to all high energy plasma applications, including focusing via auxiliary beam heating.

Surface conditioning is a means by which the adverse effects of neutral gases and impurities can be controlled or mitigated in a restraint system. To this end, the FRC system 10 provided by the present invention employs titanium and lithium deposition systems 810 and 820, the titanium and lithium deposition systems 810 and 820 applying a Ti and/or Li thin film (tens of microns thick) to the plasma-facing surfaces of the diverter 300 and confinement chamber (or vessel 100). The coating is achieved via a vapor deposition technique. Solid Li and/or Ti is evaporated and/or sublimated and sprayed onto nearby surfaces to form a coating. The source is a atomic furnace with a pilot nozzle (in the case of Li) 822 or a heated solid sphere with a pilot shroud 812 (in the case of Ti). The Li vaporizer system is typically operated in a continuous mode, while the Ti sublimator is operated primarily intermittently between plasma operations. The operating temperature of these systems is above 600 ℃ to achieve fast deposition rates. To achieve good wall coverage, multiple strategically positioned evaporator/sublimator systems are required. Fig. 9 details a preferred arrangement of gettering deposition systems 810 and 820 in FRC system 10. The coating acts as a gettering surface and effectively pumps hydrogen-based atomic and molecular species (H and D). The coating may also reduce other typical impurities, such as carbon and oxygen, to insignificant levels.

Mirror plug

As described above, FRC system 10 employs a set of mirror coils 420, 430, and 444 as shown in fig. 2 and 3. The first mirror coil set 420 is located at both axial ends of the confinement chamber 100 and is independently excited by the confinement coils 412, 414 and 416 of the main magnet system 410. The first mirror coil set 420 primarily helps to steer the FRC450 during merge and axially accommodate the FRC450 and provide equalization shaping control over duration. The first set of mirror coils 420 produces a nominally/nominally higher magnetic field (about 0.4 to 0.5T) than the central confinement field produced by the central confinement coil 412. A second set 430 of mirror coils, comprising three compact quasi-dc mirror coils 432, 434 and 436, is located between the formation section 200 and the divertor 300 and is driven by a common switching power supply. The mirror coils 432, 434, and 436, as well as the more compact pulsed mirror plug coil 444 (powered by the capacitive power supply) and the physical narrowing 442, together form a mirror plug 440, the mirror plug 440 providing a narrow low gas conduction path with a very high magnetic field (between 2 and 4T, with a rise time of between about 10 and 20 ms). The most compact pulse mirror coil 444 has a compact radial dimension, a 20cm inner bore and similar length compared to the over one meter scale (meter-plus-scale) inner bore and pancake design of the confinement coils 412, 414 and 416. The purpose of the mirror plug 440 is diversified: (1) the coils 432, 434, 436 and 444 closely bunch and direct the magnetic flux surface 452 and end-flowing plasma jet 454 into the remote divertor chamber 300. This ensures that the discharged particles properly reach divertor 300 and that there is a continuous flux surface 455, the trace of which runs from the open field line 452 region of the central FRC450 all the way to divertor 300. (2) The physical constriction 442 in the FRC system 10 provides an obstruction to the flow of neutral gas from the plasma gun 350 seated in the divertor 300, and the coils 432, 434, 436, and 444 can transmit the magnetic flux surface 452 and plasma jet 454 through the constriction 442. Likewise, constriction 442 prevents gas from forming section 200 from flowing back to divertor 300 thereby reducing the amount of neutrals introduced into the overall FRC system 10 when starting the FRC. (3) The strong axial mirror created by coils 432, 434, 436, and 444 reduces axial particle loss and thus reduces the parallel particle diffusivity over the open field line.

Axial plasma gun

The plasma flow from the gun 350 installed in the divertor chamber 310 of the divertor 300 is intended to improve stability and neutral beam performance. The gun 350 is mounted on an axis inside the chamber 310 of the divertor 300, as shown in fig. 3 and 10, and generates a plasma that flows in the divertor 300 along the open flux lines 452 and toward the center of the confinement chamber 100. The gun 350 operates with a high density gas discharge in a gasket-stack channel and is designed to generate a fully ionized plasma of thousands of amps for 5 to 10 ms. The gun 350 includes a pulsed magnetic coil that matches the output plasma flow to the desired plasma size in the confinement chamber 100. The technical parameters of the gun 350 are characterized by having channels of 5 to 13cm outer diameter and up to about 10cm inner diameter and providing a discharge current of 10 to 15kA at 400 to 600V with an in-gun magnetic field of between 0.5 to 2.3T.

The gun plasma energy penetrates the magnetic field of the mirror plug 440 and flows into the formation section 200 and the confinement chamber 100. The efficiency of plasma transfer through the mirror plug 440 increases as the distance between the gun 350 and the plug 440 decreases and the plug 440 is made wider and shorter. Under reasonable conditions, the guns 350 may each deliver about 10²²The protons pass through the 2-to-4T mirror plug 440 with high ion and electron temperatures of about 150-300 eV and about 40-50 eV, respectively. The gun 350 provides a large amount of refueling to the FRC edge layer 456 and improves total FRC particle confinement.

To further increase the plasma density, additional gas may be charged from the gun 350 into the plasma stream using a gas box. This technique allows to increase the plasma density of the jet several times. In the FRC system 10, the gas box mounted on the divertor 300 side of the mirror plug 440 improves FRC edge layer 456 refueling, FRC450 formation, and plasma line strapping.

Knowing all the adjustment parameters discussed above and also considering that it is possible to operate with only one or with two guns, it is clear that a wide range of operating modes can be provided.

Bias electrode

The electrical bias of the open flux surface may provide a radial potential that causes azimuthal E x B motion that provides a control mechanism similar to turning a knob to control the rotation of the open field line plasma and the actual FRC core 450 via velocity shear. To achieve this control, FRC system 10 employs various electrodes strategically placed on various parts of the machine. Fig. 3 depicts biasing electrodes positioned at preferred locations within FRC system 10.

In principle, there are 4 types of electrodes: (1) a point electrode 905 in the confinement chamber 100 in contact with a specific open field line 452 in the edge of the FRC450 to provide local charging; (2) a ring electrode 900 charging the distal edge flux layer 456 azimuthally symmetrically between the confinement chamber 100 and the forming section 200; (3) a stack of concentric electrodes 910 in the divertor 300 that charge the plurality of concentric flux layers 455 (whereby the selection of layers can be controlled by adjusting the coils 416 to adjust the divertor magnetic field so as to terminate the desired flux layer 456 on the appropriate electrode 910); and finally (4) the anode 920 (see fig. 10) of the plasma gun 350 itself (which intercepts the inner open flux surface 455 near the interface of the FRC 450). For some of these electrodes, fig. 10 and 11 show some typical designs.

In all cases, the electrodes are driven by a pulsed or direct current power supply at a voltage of up to about 800V. Depending on the electrode size and what the flux surface intersects, currents in the kiloamp range may be consumed.

FRC System-non-continuous operation of conventional protocol

Standard plasma formation on the FRC system 10 follows well-developed reverse field theta pinch techniques. A typical process for starting the FRC begins with driving the quasi-dc coils 412, 414, 416, 420, 432, 434, and 436 to steady state operation. The RFTP pulse power circuit of the pulse power generation system 210 then drives the pulsed fast reverse magnetic field coil 232 to create a temporary reverse bias voltage of about-0.05T in the generation section 200. At this point, a predetermined amount of neutral gas at 9-20psi is injected into the two forming volumes defined by the quartz tube chambers 240 of the (north-south) forming section 200 via a set of azimuthally oriented charging valleys (puff-vale) at the flanges at the outer ends of the forming section 200. Thereafter, a small RF (-hundreds of kilohertz) field is generated from the collection of antennas on the surface of the quartz tube 240 to cause pre-ionization in the form of localized seed ionization regions within the neutral gas column. This is followed by applying theta-ringing modulation to the current driving the pulsed fast reverse magnetic field coil 232, which leads to a more comprehensive pre-ionization of the gas column. Finally, the main set of pulsed power of the pulsed power formation system 210 is fired to drive the pulsed fast reverse magnetic field coil 232 to form a forward bias field of up to 0.4T. This step may be timed so that the forward bias field is generated uniformly over the entire length of the forming tube 240 (static formation) or so that continuous peristaltic field modulation is achieved along the axis of the forming tube 240 (dynamic formation).

During this entire formation, the actual field reversal in the plasma occurs rapidly within about 5 μ s. The multi-megawatt pulsed power delivered to the plasma being formed tends to generate thermal FRCs that then exit the forming section 200 via the application of a timing modulation of the forward magnetic field (magnetic peristalsis) or a temporarily increased current in the last coil of the coil set 232 near the axially outer end of the forming tube 210 (forming an axial magnetic field gradient directed axially toward the confinement chamber 100). The two (north-south) formation FRCs thus formed and accelerated then expand into the larger diameter confinement chamber 100, where the quasi-dc coils 412 generate a forward bias field to control radial expansion and provide a balanced external magnetic flux.

The FRC collides once the north-south formation FRC reaches near the mid-plane of the confinement chamber 100. during the collision, the axial kinetic energy of the north-south formation FRC is largely thermalized as the FRC eventually merges into a single FRC 450. A larger set of plasma diagnostics can be provided in the confinement chamber 100 to study the equilibrium of the FRC 450. typical operating conditions in the FRC system 10 produce a composite FRC with a separatrix radius of about 0.4m and an axial extension of about 3 m. an additional external magnetic field characterized by about 0.1T, about 5 × 10¹⁹m^-3And a total plasma temperature of up to 1 keV. Without any persistence, i.e., without heating and/or without current drive via neutral beam ejection or other auxiliary devices, the lifetime of these FRCs is limited to about 1ms, which is the intrinsic characteristic configuration decay time.

Experimental data for non-continuous operation-routine protocol

FIG. 12 shows repulsive flux radiiTypical time evolution of, repulsive flux radiusApproximate boundary surface radius r_sTo illustrate the dynamics of the theta-pinch merging process of the FRC 450. Two (north-south) individual plasma clusters are generated simultaneously and at supersonic velocity V_Z250km/s are accelerated out of the respective forming section 200 and collide near the mid-plane at z =0. During collisions, the plasma clusters are compressed in the axial direction, then rapidly expand radially and axially, and then eventually merge to form the FRC 450. Both radial and axial dynamics of the combined FRC450 are confirmed by detailed density profile measurements and radiometer-based tomography.

Data from a representative non-sustained discharge of FRC system 10 is shown as a function of time in fig. 13. FRC starts at t =0. The repulsive flux radius at the machine axial midplane is shown in fig. 13 (a). These data are obtained from an array of magnetic probes located slightly inside the stainless steel wall of the confinement chamber, which measure the axial magnetic field. Steel walls are good flux holders for this discharge time scale.

The line integral density is shown in fig. 13 (b), from the 6-chord CO located at z =0₂A/He-Ne interferometer. The inverse Abel transform yields the isopycnic lines of fig. 13 (c) taking into account the vertical (y) FRC displacement as measured by bolometric tomography. After some axial and radial sloshing during the first 0.1ms, the FRC is stabilized with a hollow density distribution. This distribution is fairly flat with significant density along the axis as required by typical 2-D FRC equalization.

The total plasma temperature, obtained from pressure equilibrium and in full agreement with thomson scattering and spectroscopy measurements, is shown in fig. 13 (d).

Analysis from the entire repulsive flux array showed that the shape of the FRC interface (approximated by the repulsive flux axial distribution) evolved gradually from a racetrack shape to an ellipse. This evolution, shown in fig. 14, is consistent with a gradual magnetic reconnect from two FRCs to a single FRC. In fact, a rough estimate shows that about 10% of the two initial FRC flux reconnects during the collision in this particular case.

During FRC life, the FRC length steadily shrinks from 3m to about 1 m. this shrinkage, as can be seen in FIG. 4, indicates that most of the convective energy loss dominates the FRC confinement since the plasma pressure inside the separatrix decreases more rapidly than the external magnetic pressure, the magnetic field line tension in the end region compresses the FRC axially, restoring axial and radial equilibrium, for the discharges discussed in FIGS. 13 and 14, FRC magnetic flux, particle inventory and thermal energy (about 10 mWb, 7 × 10, respectively) when FRC equilibrium appears to subside¹⁹Particles and 7 kJ) decreased by roughly one order of magnitude in the first millisecond.

Continuous operation-HPF protocol

The examples in fig. 12 to 14 are characteristic of the FRC without any sustained attenuation. However, several techniques are deployed on FRC system 10 to further improve the FRC constraints (inner core and edge layers) of the HPF scheme and to continue this configuration.

Neutral beam

First, fast (H) neutrals are perpendicular to B in the beam from the eight neutral beam injectors 600_ZAnd ejected. The beam of fast neutrals is ejected starting from the moment the formation of FRCs from north and south merges into one FRC450 in the confinement chamber 100. Fast ions formed primarily by charge exchange have betatron orbits with azimuthal currents added to the FRC450 (with FRC topology scales or at least a major radius much larger than the characteristic magnetic field gradient length scales). After some portion of the discharge (after 0.5 to 0.8ms entry into the shot), the population of sufficiently large fast ions significantly improves the intrinsic FRC stability and confinement characteristics (see, e.g., m.w. binder and n. rotoker, Plasma phys. 56, part 3, 451 (1996)). And, fromFrom a continuing perspective, the beam from the neutral beam injector 600 is also the primary means to drive the current and heat the FRC plasma.

In the plasma scheme of FRC system 10, fast ions primarily slow down plasma electrons. The typical orbital mean decay time of fast ions during the early part of the discharge is 0.3 to 0.5ms, which results in significant FRC heating of mainly electrons. The fast ions undergo a larger radial drift outside the separatrix because the internal FRC magnetic field is inherently lower (about 0.03T on average for an external axial field of 0.1T). If the neutral gas density is too high outside the interface, the fast ions will be susceptible to charge exchange losses. Accordingly, wall gettering and other techniques (such as plasma guns 350 and mirror plugs 440 to facilitate gas control, etc.) deployed on the FRC system 10 tend to minimize edge neutrals and can allow for the desired rapid ion current build-up.

Pellet injection

When a significantly fast population of particles accumulates within the FRC450, frozen H or D pellets are injected from the pellet injectors 700 into the FRC450 to maintain the FRC particle inventory of the FRC450 due to higher electron temperatures and longer FRC life. The expected ablation time scale is short enough to provide a significant source of FRC particles. This rate can be increased by enlarging the surface area of the jet by breaking up individual pellets into smaller pieces when in the barrel or jet of the pellet injector 700 and before entering the confinement chamber 100, which step can be achieved by increasing the friction between the pellets and the jet wall by tensioning the bend radius of the last section of the jet just before entering the confinement chamber 100. By varying the firing order and rate of the 12 barrels (injection tubes) and the split, the pellet injection system 700 can be tuned to provide particle inventory at only the desired level. This in turn helps to maintain internal dynamic pressure in the FRC450 and continues the operation and life of the FRC 450.

Once the ablated atoms encounter the bulk plasma in the FRC450, they become fully ionized. The resulting cold plasma part is then collisionally heated by the native FRC plasma. The energy required to maintain the desired FRC temperature is ultimately supplied by the beam injector 600. In this sense, the pellet injector 700 together with the neutral beam injector 600 form a system that maintains a steady state and continues the FRC 450.

Saddle coil

To achieve steady state current drive and maintain the desired ion current, it is desirable to prevent or significantly reduce electron spin acceleration (due to collisional ion electron momentum transfer) due to electron-ion friction. FRC system 10 utilizes innovative techniques to provide electron breaking (electron breaking) via externally applied static magnetic dipole or quadrupole fields. This is achieved via the external saddle coil 460 depicted in fig. 15. The radial magnetic field applied laterally from the saddle coil 460 induces an axial electric field in the rotating FRC plasma. The resulting axial electron current interacts with the radial magnetic field to produce an azimuthal breaking force, F, on the electrons_θ=. For typical conditions in FRC system 10, the magnetic dipole (or quadrupole) field that needs to be applied inside the plasma needs to be only about 0.001T to provide sufficient electron breaking. The corresponding external field of about 0.015T is small enough not to cause significant rapid particle loss or otherwise adversely affect confinement. In effect, the applied magnetic dipole (or quadrupole) field helps to suppress instability. In combination with tangential neutral beam injection and axial plasma injection, the saddle coil 460 provides an additional level of control with respect to current maintenance and stability.

Mirror plug

The design of the pulsed coil 444 within the mirror plug 440 allows for the local generation of high magnetic fields (2 to 4T) with modest (about 100kJ) capacitive energy. To create a magnetic field typical of the operation of the present invention of the FRC system 10, all field lines within the volume being created pass through the narrowing 442 at the mirror plug 440, as shown by the magnetic field lines in fig. 2, and no plasma wall contact occurs. Also, the mirror plug 440 in series with the collimated flow divertor magnet 416 can be adjusted to direct the field lines onto the divertor electrode 910, or to flare the field lines outward into an end cusp/cusp (cusp) configuration (not shown). The end hook configuration improves stability and inhibits parallel electron thermal conduction.

The mirror plug 440 itself also contributes to neutral gas control. The mirror plug 400 allows for better utilization of deuterium gas charge into the quartz tube during FRC formation, as less gas conduction by the plug (500L/s) significantly reduces gas backflow into the divertor 300. Most of the residual charge gas inside the formation tube 210 is rapidly ionized. In addition, the high density plasma flowing through the mirror plug 440 provides efficient neutral ionization and therefore an effective gas barrier. Thus, most of the neutrals from the FRC edge layer 456 that are recirculated in the divertor 300 do not return to the confinement chamber 100. Furthermore, neutrals associated with operation of the plasma gun 350 (as discussed below) will be primarily confined to the divertor 300.

Finally, the mirror plug 440 tends to improve the FRC edge layer constraint. Edge layer particle confinement time with a mirror ratio (plug/confinement field) in the range of 20 to 40 and a length of 15m between north and south mirror plugs 440Increasing by at most one order of magnitude. Improvements in or relating toTending to increase FRC particle confinement.

Assuming that the radial diffusivity (D) particle loss from interfacial volume 453 is dominated by the axial loss from edge layer 456: () Equilibrating to obtainFrom this equation, the interface density gradient length can be rewritten as. Here, r_s、L_sAnd n_sThe radius of the interface, the length of the interface and the density of the interface are respectively. FRC particle confinement time ofWhereinAnd is. Physically, improvementResulting in increased (reduced interface density gradient and drift parameters) and, therefore, reduced FRC particle loss. The overall improvement in FRC particle confinement is generally slightly less than square (quadratic) because n_sWith followingAnd (4) increasing.

Significant improvements also require that edge layer 456 remain generally stable (i.e., no n =1 flute (flute), hose/fire hose (fire hose), or other MHD instabilities typical of open systems). The use of the plasma gun 350 provides this preferred edge stability. In this regard, the mirror plug 440 and the plasma gun 350 form an effective edge control system.

Plasma gun

The plasma gun 350 improves the stability of the FRC discharge jet 454 by line-tying. Gun plasma from the plasma gun 350 generates no azimuthal angular momentum, which proves useful for controlling FRC rotational instability. As such, the gun 350 is an effective means of controlling FRC stability without the need for older quadrupole stabilization techniques. Thus, the plasma gun 350 enables the benefits of fast particles to be exploited or advanced hybrid kinetic FRC schemes as outlined in the present disclosure to be employed. Thus, the plasma gun 350 enables the FRC system 10 to operate with saddle coil currents that are only sufficient for electron breakdown but below a threshold that would cause FRC instability and/or result in significantly rapid particle diffusion.

As mentioned in the discussion of the mirror plug above, ifCan be significantly improved, the supplied gun plasma will have a loss rate of particles from the edge layer of (-10)²²In/s) are equivalent. The lifetime of the gun-generated plasma in FRC system 10 is in the millisecond range. In practice, it is considered to have n_e~10¹³cm^-3A gun plasma of density and ion temperature of about 200 eV is confined between the end mirror plugs 440. The catch length L and mirror ratio R were about 15m and 20, respectively. The mean free path of ions due to coulomb collisions isAnd due to the fact thatIons are confined in a gas dynamic state. The plasma confinement time in this state isIn which V is_sIs the ion sound velocity. For comparison, the classical ion confinement times for these plasma parameters would be. The anomalous lateral diffusion can in principle shorten the plasma confinement time. However, in the FRC system 10, if Bohm diffusivity is assumed, the estimated lateral confinement time of the gun plasma is. Thus, the gun will provide significant refueling and improved total FRC particle confinement to the FRC edge layer 456.

Also, the gun plasma stream may be turned on in about 150 to about 200 microseconds, which allows for FRC initiation, translation, and incorporation into the confinement chamber 100. If turned on at about t-0 (FRC major group onset), the gun plasma helps to sustain the FRC450 that is currently dynamically formed and merged. The combined particle inventory from the formation FRC and from the gun is sufficient for neutral beam trapping, plasma heating and long persistence. If t is turned on in the range of-1 to 0ms, the gun plasma may fill the quartz tube 210 with plasma or ionize the gas charge into the quartz tube, thus allowing the formation of FRC with reduced or possibly even zero charge gas. FRC formation with zero charge gas may require a sufficiently cold plasma formation to allow rapid diffusion of the reverse bias magnetic field. If at t<2 ms on, the plasma flow can be about 1 to 3m towards the formation and confinement regions of the formation section 200 and the confinement chamber 100³The field line volume is filled by a number 10¹³cm^-3Is sufficient to allow neutral beam accumulation before FRC arrival. The formation FRC may then be formed and translated into the resulting confined vessel plasma. In this manner, the plasma gun 350 can allow a wide variety of operating conditions and parameter regimes to be achieved.

Electric bias

Control of the radial electric field distribution in the edge layer 456 is beneficial to FRC stability and confinement in various ways. Due to the innovative biasing components deployed in the FRC system 10, a variety of carefully planned potential distributions can be applied to a set of open flux surfaces across the machine from regions completely outside the central confinement region in the confinement chamber 100. In this way, a radial electric field may be generated on the edge layer 456 slightly outside the FRC 450. These radial electric fields then modify the azimuthal rotation of the edge layer 456 and achieve its confinement via E × B velocity shear. Any differential rotation between the edge layer 456 and the FRC core 453 can then be transmitted to the FRC plasma inside by shearing. Thus, the control edge layer 456 directly affects the FRC core 453. Moreover, this technique provides a direct means to control the onset and growth of instabilities, since free energy in plasma rotation may also cause instabilities. In the FRC system 10, appropriate edge biasing provides effective control over open field wire transport and rotation, as well as FRC core rotation. The position and shape of the various provided electrodes 900, 905, 910, and 920 allow control of different sets 455 of flux surfaces and at different and independent potentials. In this way, a large number of different electric field configurations and strengths can be achieved, each having a different characteristic effect on plasma performance.

A key advantage of all these innovative biasing techniques is that the core and edge plasma behavior can be achieved from the FRC plasma completely outside, i.e. without having any physical components touching the central thermal plasma (which would likely have a severe impact on energy, flux and particle losses). This has a significant beneficial effect on the performance and all possible applications of the HPF concept.

Test data-HPF operation

The ejection of fast particles from the neutral beam gun 600 via the beam plays an important role in allowing the implementation of HPF schemes. Fig. 16 shows this reality. A set of curves is depicted showing how the lifetime of the FRC is related to the beam pulse length. All other operating conditions were kept constant for all discharges comprising this study. The data of multiple shots (shots) are averaged and thus represent typical behavior. It is apparent that longer beam durations produce longer lifetime FRCs. Considering this evidence and other diagnoses during this study, it was demonstrated that the beam increased stability and reduced losses. The correlation between beam pulse length and FRC lifetime is not ideal because beam trapping becomes inefficient below a certain plasma size, i.e., not all of the jet beam is intercepted and trapped because the physical size of the FRC450 shrinks. The contraction of the FRC is mainly due to the fact that for a particular experimental setup, the net energy loss from the FRC plasma during discharge (-4 MW) is slightly greater than the total power fed into the FRC via the neutral beam (-2.5 MW). Locating the beam closer to the mid-plane of the vessel 100 will tend to reduce these losses and extend FRC life.

Fig. 17 shows the effect of different components on implementing the HPF scheme. It shows a series of typical curves that plot the lifetime of the FRC450 as a function of time. In all cases, a constant, modest amount of beam power (about 2.5 MW) was injected for the entire duration of each discharge. Each curve represents a different combination of components. For example, operating FRC system 10 without any mirror plugs 440, plasma guns 350, or gettering from gettering system 800 results in rapid onset of rotational instability and FRC topology loss. Adding only the mirror plug 440 delays the onset of instability and increases the constraint. The use of the mirror plug 440 in combination with the plasma gun 350 further reduces instability and extends FRC life. Finally, the best results are obtained with gettering (Ti in this case) in addition to the gun 350 and plug 440, the resulting FRC being free of instability and exhibiting the longest lifetime. From this experimental demonstration it is clear that the complete combination of components produces the best effect and provides a beam with the best target conditions.

As shown in fig. 1, the newly discovered HPF solution shows significantly improved transport behavior. Fig. 1 shows the particle confinement time variation of the FRC system 10 between the conventional scheme and the HPF scheme. As can be seen, in the HPF scheme it improves by a factor well over 5. Further, fig. 1 details the particle confinement time of FRC system 10, as compared to the particle confinement time in prior conventional FRC experiments. With respect to these other machines, the HPF scheme of FRC system 10 has been between 5 and closeThe coefficients between 20 improve the constraint. Finally and most importantly, the nature of the constraint scaling of the FRC system 10 in the HPF scheme is significantly different from all previous measurements. Prior to establishing the HPF scheme in FRC system 10, various empirical scaling laws were derived from the data to predict the constraint time in prior FRC experiments. All those scaling rules are roughly proportionalWhere R is the radius of the FRC-free magnetic field (rough measurement of the physical scale of the machine) andthe ion lamor radius evaluated in an externally applied field (rough measurement of applied magnetic field). It is apparent from fig. 1 that the long constraint in conventional FRCs is only possible at larger machine sizes and/or high magnetic fields. Operating the FRC system 10 in the conventional FRC scheme CR tends to follow those scaling rules, as shown in fig. 1. However, the HPF solution is extremely advantageous and shows that better confinement can be achieved without the need for larger machine sizes or high magnetic fields. More importantly, it is also apparent from fig. 1 that the HPF scheme results in improved confinement time with reduced plasma size compared to the CR scheme. Similar trends can also be seen for flux and energy confinement times, which increase by a factor of 3-8 in the FR system 10, as described below. Breakthroughs in the HPF scheme can thus allow FRC equalization in FRC system 10 and future higher energy machines to be sustained and maintained using moderate beam power, lower magnetic fields, and smaller magnitudes. Coexisting with these improvements are lower operating and construction costs and reduced engineering complexity.

For further comparison, fig. 18 shows data derived from a representative HPF scheme discharge in FRC system 10 as a function of time. Fig. 18 (a) depicts the repulsive flux radius at the mid-plane. For these longer timescales, the conductive steel wall is no longer a good flux holder and the magnetic probes inside the wall are enlarged with the probes outside the wall to properly compensate for the magnetic flux diffusion through the steel. The HPF scheme mode of operation exhibits a longer lifetime of over 400% compared to typical performance in the conventional scheme CR, as shown in fig. 13.

Representative chords of the line integral density trace are shown in fig. 18 (b) and their Abel inverse transform complement, isopycnic lines are shown in fig. 18 (c). Compared to the conventional FRC scheme CR, as shown in fig. 13, the plasma is quieter throughout the pulse, indicating very stable operation. The peak density was also slightly lower in the HPF shot, which is a result of the hotter total plasma temperature (a factor of up to 2), as shown in fig. 18 (d).

For the corresponding discharges shown in fig. 18, the energy, particle, and flux confinement times are 0.5ms, 1ms, and 1ms, respectively. At a reference time of 1ms into the discharge, the stored plasma energy is 2kJ, and the loss is about 4MW, making this target well suited for neutral beam persistence.

Fig. 19 summarizes all the advantages of the HPF scheme in the newly established experimental HPF flux constraint calibration format. As can be seen in fig. 19, based on measurements made before and after t =0.5ms, i.e. t<0.5ms and t>0.5ms, the constraint scales with the approximate square of the electron temperature. Having a T_eThis strong scaling of positive (and non-negative) powers of (f) is in stark contrast to the scaling exhibited by conventional tokamaks, where the constraint is typically inversely proportional to some power of the electron temperature. This scaling appears as a direct result of the HPF states and large orbits (i.e., orbits scaled by FRC topology and/or at least the characteristic magnetic field gradient length) ion population. Fundamentally, this new calibration is significantly beneficial for high operating temperatures and can allow for relatively modest reactor sizes.

While the invention is susceptible to various modifications and alternative forms, specific examples thereof have been shown in the drawings and are herein described in detail. It should be understood, however, that the invention is not to be limited to the particular forms or methods disclosed, but to the contrary, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the appended claims.

In the description above, for purposes of explanation only, specific nomenclature is set forth to provide a thorough understanding of the present disclosure. It will be apparent, however, to one skilled in the art that these specific details are not required in order to practice the teachings of the present disclosure.

The various features of the representative examples and the appended claims may be combined in ways that are not specifically and explicitly enumerated in order to provide additional useful embodiments of the present teachings. It should also be expressly noted that the indication of all value ranges or groups of entities discloses every possible intermediate value or intermediate entity for the purpose of original disclosure as well as for the purpose of limiting the claimed subject matter.

Systems and methods for generating and maintaining an FRC of an HPF scheme are disclosed. It is to be understood that the embodiments described herein are for purposes of illustration and are not to be construed as limiting the subject matter of the present disclosure. Various modifications, uses, substitutions, combinations, improvements, methods of manufacture, without departing from the scope or spirit of the invention, will be apparent to those skilled in the art. For example, the reader will appreciate that the specific ordering and combination of process actions described herein is merely illustrative, unless stated otherwise, and that the invention can be performed using different or additional process actions, or a different combination or ordering of process actions. As another example, each feature of one embodiment may be mixed and matched with other features shown in other embodiments. Features and processes known to those skilled in the art may likewise be incorporated as desired. Furthermore and obviously, features may be added or subtracted as desired. Accordingly, the invention is not to be restricted except in light of the attached claims and their equivalents.

Claims (82)

1. A method of generating and maintaining a magnetic field using a Field Reversed Configuration (FRC), comprising:

generating a magnetic field using a magnetic system coupled to a confinement chamber, first and second diametrically opposed FRC formation sections coupled to the confinement chamber, and first and second divertors coupled to the first and second formation sections, the magnetic system including first and second mirror plugs and two or more saddle coils coupled to the confinement chamber, the first and second mirror plugs positioned between the first and second formation sections and the first and second divertors,

gettering the confinement chamber and the first and second divertors using a layer of gettering material from a gettering system coupled to the confinement chamber and the first and second divertors,

generating an FRC in each of the first and second formation sections and translating each FRC toward a mid-plane of the confinement chamber where the FRCs merge into a merged FRC, the first and second formation sections including a modular formation system,

ejecting neutral atom beams into the merged FRC from a plurality of neutral atom beam ejectors coupled to the confinement chamber and oriented orthogonal to an axis of the confinement chamber,

injecting plasma into the merged FRC from first and second axial plasma guns operably coupled to the first and second divertors, the first and second formation sections, and the confinement chamber,

electrically biasing the open flux surface of the merged FRC with one or more biasing electrodes positioned in one or more of the confinement chamber, the first and second formation sections, and the first and second divertors, and

injecting ion pellets into the merged FRC from an ion pellet injector coupled to the confinement chamber.

2. The method of claim 1 wherein the particle confinement ratio of the combined FRC has substantially the same magnetic field radius (R) and is substantially dependent on R²/ρ_iThe particle constraint of the particle constraint scaled FRC is larger by a deviation of a factor of at least 2, where p_iIs the ion lamor radius evaluated in an externally applied field.

3. The method of claim 1 wherein the magnetic system comprises a plurality of quasi-dc coils axially spaced in position along the confinement chamber, the first and second formation sections, and the first and second divertors.

4. The method of claim 3, wherein the magnetic system further comprises a first set of mirror coils positioned between the first and second formation sections and an end of the confinement chamber.

5. The method of claim 4 wherein the mirror plug comprises a second set of mirror coils interposed between the first and second formation sections and each of the first and second divertors.

6. The method of claim 5 wherein the mirror plug further comprises a set of mirror plug coils wrapped around a constriction in the passageway between each of the first and second formation sections and the first and second divertors.

7. The method of claim 6, wherein the mirror plug coil is a compact pulsed mirror coil.

8. The method of claim 1 wherein the first and second formation sections comprise elongated tubes.

9. The method of claim 8, wherein the forming system is a pulsed power forming system.

10. The method of claim 8, wherein the step of forming and translating the FRCs comprises: energizing a set of coils of individual ones of a plurality of strap assemblies wound around the elongate tube of the first and second formation sections, wherein the formation system includes a plurality of power and control units coupled to individual ones of the plurality of strap assemblies.

11. The method of claim 10, wherein individual ones of the plurality of power and control units comprise a trigger and control system.

12. The method of claim 11 wherein the triggering and control systems of the individual ones of the plurality of power and control units are synchronizable to allow static FRC formation in which the FRC is formed and then injected, or dynamic FRC formation in which the FRC is simultaneously formed and translated.

13. The method of claim 1, wherein the plurality of neutral atom beam injectors comprises one or more RF plasma source neutral atom beam injectors and one or more arc source neutral atom beam injectors.

14. The method of claim 1 wherein the plurality of neutral atom beam injectors are oriented with the injection path tangential to the FRC with the target trapping zone within the interface of the FRC.

15. The method of claim 14 wherein the pellet injector is a 12-barrel pellet injector coupled to the confinement chamber and oriented to direct ion pellets into the FRC.

16. The method of claim 1, wherein the gettering system comprises one or more of a titanium deposition system and a lithium deposition system that coat plasma-facing surfaces of the confinement chamber and the first and second divertors.

17. The method of claim 1, wherein the biasing electrode comprises one or more of: one or more point electrodes positioned within the confinement chamber to contact open field lines; a set of ring electrodes azimuthally symmetric charging a distal rim flux layer between the confinement chamber and the first and second formation sections; a plurality of concentrically stacked electrodes positioned in the first and second divertors to charge a plurality of concentric flux layers; and an anode of the plasma gun to intercept the open flux.

18. A method of generating and maintaining a magnetic field with field reversed configuration (EFC), comprising:

generating a magnetic field using a magnetic system coupled to a confinement chamber, first and second diametrically opposed FRC formation sections coupled to the confinement chamber, and first and second divertors coupled to the first and second formation sections,

generating FRCs in each of the first and second formation sections and translating each FRC toward a mid-plane of the confinement chamber, where the FRCs merge into a merged FRC,

injecting neutral atom beams into the merged FRC from a plurality of neutral atom beam injectors coupled to the confinement chamber and oriented orthogonal to an axis of the confinement chamber, an

Injecting plasma into the merged FRC from first and second axial plasma guns operably coupled to the first and second divertors, the first and second formation sections, and the confinement chamber.

19. The method of claim 18 wherein the particle confinement ratio of the merged FRC has a substantially constant valueThe radius (R) of the same magnetic field and being substantially dependent on R²/ρ_iThe particle constraint of the particle constraint scaled FRC is larger by a deviation of a factor of at least 2, where p_iIs the ion lamor radius evaluated in an externally applied field.

20. The method of claim 18 wherein the magnetic system comprises a plurality of quasi-dc coils axially spaced in position along the confinement chamber, the first and second formation sections, and the first and second divertors.

21. The method of claim 20 wherein the magnetic system further comprises a first set of mirror coils positioned between the first and second formation sections and an end of the confinement chamber.

22. The method of claim 21 wherein the mirror plug comprises a second set of mirror coils interposed between the first and second formation sections and each of the first and second divertors.

23. The method of claim 22 wherein the mirror plug further comprises a set of mirror plug coils wound around a constriction in the passageway between each of the first and second formation sections and the first and second divertors.

24. The method of claim 23, wherein the mirror plug coil is a compact pulsed mirror coil.

25. The method of claim 18, further comprising: injecting plasma into the merged FRC from first and second axial plasma guns operably coupled to the first and second divertors, the first and second formation sections, and the confinement chamber.

26. The method of claim 18, further comprising: gettering the confinement chamber and the first and second divertors using a layer of gettering material from a gettering system coupled to the confinement chamber and the first and second divertors.

27. The method of claim 18, further comprising: electrically biasing an open flux surface of the merged FRC using one or more biasing electrodes positioned within one or more of the confinement chamber, the first and second formation sections, and the first and second divertors.

28. The method of claim 18, further comprising two or more coils coupled to the confinement chamber.

29. The method of claim 18, further comprising: injecting ion pellets into the merge FRC from an ion pellet injector coupled to the confinement chamber.

30. The method of claim 18, wherein the forming section comprises a modular forming system for generating and translating the FRC toward a mid-plane of the confinement chamber.

31. A method of generating and maintaining a magnetic field with field reversed configuration (EFC), comprising:

generating a magnetic field using a magnetic system coupled to a confinement chamber, first and second diametrically opposed FRC formation sections coupled to the confinement chamber, and first and second divertors coupled to the first and second formation sections,

generating FRCs in each of the first and second formation sections and translating each FRC toward a mid-plane of the confinement chamber, where the FRCs merge into a merged FRC,

injecting neutral atom beams into the merged FRC from a plurality of neutral atom beam injectors coupled to the confinement chamber and oriented orthogonal to an axis of the confinement chamber, an

Electrically biasing the open flux surface of the merged FRC with one or more biasing electrodes positioned in one or more of the confinement chamber, the first and second formation sections, and the first and second divertors.

32. The method of claim 31 wherein the particle confinement ratio of the combined FRC has substantially the same magnetic field radius (R) and is substantially dependent on R²/ρ_iThe particle constraint of the particle constraint scaled FRC is larger by a deviation of a factor of at least 2, where p_iIs the ion lamor radius evaluated in an externally applied field.

33. The method of claim 31, wherein the biasing electrode comprises one or more of: one or more point electrodes positioned within the confinement chamber to contact open field lines; a set of ring electrodes azimuthally symmetric charging a distal rim flux layer between the confinement chamber and the first and second formation sections; a plurality of concentrically stacked electrodes positioned in the first and second divertors to charge a plurality of concentric flux layers; and an anode of the plasma gun to intercept the open flux.

34. The method of claim 31 wherein the magnetic system comprises a plurality of quasi-dc coils axially spaced in position along the confinement chamber, the first and second formation sections, and the first and second divertors.

35. The method of claim 34 wherein the magnetic system further comprises a first set of mirror coils positioned between the first and second formation sections and an end of the confinement chamber.

36. The method of claim 35 wherein the magnetic system further comprises first and second mirror plugs, wherein the first and second sets of mirror plugs comprise a second set of mirror coils interposed between the first and second formation sections and each of the first and second divertors.

37. The method of claim 36 wherein the first and second mirror plugs further comprise a set of mirror plug coils wrapped around a constriction in the passageway between each of the first and second formation sections and the first and second divertors.

38. The method of claim 37, wherein the mirror plug coil is a compact pulsed mirror coil.

39. The method of claim 31 further comprising the step of energizing a set of coils of individual ones of the strap assemblies wrapped around the elongate tube of the first and second formation sections, wherein a plurality of power and control units of a formation system are coupled to individual ones of the plurality of strap assemblies.

40. The method of claim 39, wherein individual ones of the plurality of power and control units comprise a trigger and control system.

41. The method of claim 40 wherein the triggering and control systems of the individual ones of the plurality of power and control units are synchronizable to allow static FRC formation in which the FRC is formed and then injected, or dynamic FRC formation in which the FRC is simultaneously formed and translated.

42. The method of claim 31 wherein the plurality of neutral atom beam injectors are oriented with the injection path tangential to the FRC with the target trapping zone within the interface of the FRC.

43. The method of claim 31 further comprising ejecting example pellets into the merge FRC from an ion pellet injector coupled to the confinement chamber.

44. The method of claim 31, further comprising: two or more saddle coils coupled to the confinement chamber.

45. The method of claim 31, wherein the confinement chamber and the first and second divertors are gettered using a layer of gettering material from a gettering system coupled to the confinement chamber and the first and second divertors.

46. The method of claim 31, further comprising: injecting plasma into the merged FRC from first and second axial plasma guns operably coupled to the first and second divertors, the first and second formation sections, and the confinement chamber.

47. A method of generating and maintaining a magnetic field with field reversed configuration (EFC), comprising:

generating a magnetic field using a magnetic system coupled to a confinement chamber, first and second diametrically opposed FRC formation sections coupled to the confinement chamber, and first and second divertors coupled to the first and second formation sections,

generating FRCs in each of the first and second formation sections and translating each FRC toward a mid-plane of the confinement chamber, where the FRCs merge into a merged FRC,

injecting neutral atom beams into the merged FRC from a plurality of neutral atom beam injectors coupled to the confinement chamber and oriented orthogonal to an axis of the confinement chamber, an

Injecting plasma into the merged FRC from first and second axial plasma guns operably coupled to the first and second divertors, the first and second formation sections, and the confinement chamber.

48. The method of claim 47 wherein the particle confinement ratio of the combined FRC has substantially the same magnetic field radius (R) and is substantially dependent on R²/ρ_iThe particle constraint of the particle constraint scaled FRC is larger by a deviation of a factor of at least 2, where p_iIs the ion lamor radius evaluated in an externally applied field.

49. The method of claim 47 wherein individual ones of the first and second formation sections comprise an elongate tube and a pulsed power formation system coupled to the elongate tube.

50. The method of claim 49 including the step of energizing sets of coils of individual ones of a plurality of strap assemblies wound around the elongate tube of the first and second formation sections, the formation system including a plurality of power and control units coupled to individual ones of a plurality of strap assemblies.

51. The method of claim 50, wherein individual ones of the plurality of power and control units comprise a trigger and control system.

52. The method of claim 51 wherein the trigger and control systems of the individual ones of the plurality of power and control units are synchronizable to allow static FRC formation in which the FRC is formed and then injected, or dynamic FRC formation in which the FRC is simultaneously formed and translated.

53. The method of claim 47, further comprising: electrically biasing the open flux surface of the merged FRC with one or more biasing electrodes positioned in one or more of the confinement chamber, the first and second formation sections, and the first and second divertors.

54. The method of claim 53, wherein the one or more bias electrodes comprise one or more of: one or more point electrodes positioned within the confinement chamber to contact open field lines; a set of ring electrodes azimuthally symmetric charging a distal rim flux layer between the confinement chamber and the first and second formation sections; a plurality of concentrically stacked electrodes positioned in the first and second divertors to charge a plurality of concentric flux layers; and an anode of the plasma gun to intercept the open flux.

55. The method of claim 47 wherein the magnetic system comprises a plurality of quasi-DC coils axially spaced in position along the confinement chamber, the first and second formation sections, and the first and second divertors, and a first set of mirror coils positioned between the first and second formation sections and an end of the confinement chamber.

56. The method of claim 55 wherein the magnetic system further comprises first and second mirror plugs, wherein the mirror plug comprises a second set of mirror coils interposed between the first and second formation sections and each of the first and second divertors.

57. The method of claim 56 wherein the mirror plug further comprises a compact set of pulsed mirror plug coils wound around a constriction in the passageway between the first and second formation sections and each of the first and second divertors.

58. The method of claim 47 wherein the plurality of neutral atom beam injectors are oriented with the injection path tangential to the FRC with the target trapping zone within the interface of the FRC.

59. The method of claim 47, further comprising: injecting ion pellets into the merge FRC from an ion pellet injector coupled to the confinement chamber.

60. The method of claim 47, further comprising: two or more saddle coils coupled to the confinement chamber.

61. The method of claim 47, further comprising: gettering the confinement chamber and the first and second divertors using a layer of gettering material from a gettering system coupled to the confinement chamber and the first and second divertors.

62. A method of generating and maintaining a magnetic field with field reversed configuration (EFC), comprising:

generating a magnetic field using a magnetic system coupled to a confinement chamber, first and second diametrically opposed FRC formation sections coupled to the confinement chamber, and first and second divertors coupled to the first and second formation sections,

generating FRCs in each of the first and second formation sections and translating each FRC toward a mid-plane of the confinement chamber, where the FRCs merge into a merged FRC,

injecting neutral atom beams into the merged FRC from a plurality of neutral atom beam injectors coupled to the confinement chamber and oriented orthogonal to an axis of the confinement chamber, an

Gettering the confinement chamber and the first and second divertors using a layer of gettering material from a gettering system coupled to the confinement chamber and the first and second divertors.

63. The method of claim 62 wherein the particle confinement ratio of the merged FRC has substantially the same magnetic field radius (R) and is substantially dependent on R²/ρ_iThe particle constraint of the particle constraint scaled FRC is larger by a deviation of a factor of at least 2, where p_iIs the ion lamor radius evaluated in an externally applied field.

64. The method of claim 62, wherein the gettering system comprises one or more of a titanium deposition system and a lithium deposition system that coat plasma-facing surfaces of the confinement chamber and the first and second divertors.

65. The method of claim 64 wherein the deposition system employs a vapor deposition technique.

66. The method of claim 64, wherein said lithium deposition system comprises a plurality of atomic furnaces having pilot nozzles.

67. The method of claim 64 wherein the titanium deposition system comprises a plurality of heated solid spheres with a guide sheath.

68. The method of claim 62, further comprising: injecting plasma into the merged FRC from first and second axial plasma guns operably coupled to the first and second divertors, the first and second formation sections, and the confinement chamber.

69. The method of claim 62 wherein individual ones of the first and second formation sections comprise an elongate tube and a pulsed power formation system coupled to the elongate tube.

70. The method of claim 69, further comprising: energizing a set of coils of individual ones of a plurality of strap assemblies wound around the elongate tube of the first and second formation sections, wherein the formation system includes a plurality of power and control units coupled to individual ones of the plurality of strap assemblies.

71. The method of claim 62, further comprising: electrically biasing the open flux surface of the merged FRC with one or more biasing electrodes positioned in one or more of the confinement chamber, the first and second formation sections, and the first and second divertors.

72. The method of claim 71, wherein the one or more bias electrodes comprise one or more of: one or more point electrodes positioned within the confinement chamber to contact open field lines; a set of ring electrodes azimuthally symmetric charging a distal rim flux layer between the confinement chamber and the first and second formation sections; a plurality of concentrically stacked electrodes positioned in the first and second divertors to charge a plurality of concentric flux layers; and an anode of the plasma gun to intercept the open flux.

73. The method of claim 62, wherein the magnetic system comprises: a plurality of quasi-dc coils axially spaced in position along the confinement chamber, the first and second formation sections, and the first and second divertors; a first set of mirror coils positioned between the first and second formation sections and an end of the confinement chamber; and a second set of mirror coils between the first and second formation sections and each of the first and second divertors.

74. The method of claim 62, further comprising: a set of compact pulsed mirror coils wound around constrictions in the passages between the first and second formation sections and each of the first and second divertors.

75. A method of generating and maintaining a magnetic field with field reversed configuration (EFC), comprising:

generating a magnetic field using a magnetic system coupled to a confinement chamber, first and second diametrically opposed FRC formation sections coupled to the confinement chamber, and first and second divertors coupled to the first and second formation sections, the magnetic system comprising two or more saddle coils coupled to the confinement chamber on each side of the midplane of the confinement chamber,

generating an FRC in each of the first and second formation sections and translating each FRC to a mid-plane of the confinement chamber where the FRCs merge into a merged FRC, an

Injecting neutral atom beams into the merged FRC from a plurality of neutral atom beam injectors coupled to the confinement chamber and oriented orthogonal to an axis of the confinement chamber.

76. The method of claim 75 wherein the particle confinement ratio of the combined FRC has substantially the same magnetic field radius (R) and is substantially dependent on R²/ρ_iThe particle constraint of the particle constraint scaled FRC is larger by a deviation of a factor of at least 2, where p_iIs the ion lamor radius evaluated in an externally applied field.

77. The method of claim 75, further comprising: injecting plasma into the merged FRC from first and second axial plasma guns operably coupled to first and second divertors, the first and second formation sections, and the confinement chamber.

78. The method of claim 75 wherein individual ones of the first and second formation sections comprise an elongate tube and a pulsed power formation system coupled to the elongate tube.

79. The method of claim 75 wherein the open flux surface of the merged FRC is electrically biased by one or more biasing electrodes positioned in one or more of the confinement chamber, the first and second formation sections, and the first and second divertors.

80. The method of claim 79, wherein the one or more bias electrodes comprise one or more of: one or more point electrodes positioned within the confinement chamber to contact open field lines; a set of ring electrodes azimuthally symmetric charging a distal rim flux layer between the confinement chamber and the first and second formation sections; a plurality of concentrically stacked electrodes positioned in the first and second divertors to charge a plurality of concentric flux layers; and an anode of the plasma gun to intercept the open flux.

81. The method of claim 75, wherein the magnetic system comprises: a plurality of quasi-dc coils spaced in position along the confinement chamber, the first and second formation sections, and the first and second divertors; a first set of mirror coils positioned between the confinement chamber and ends of the first and second formation sections; and a second set of mirror coils between the first and second formation sections and each of the first and second divertors.

82. The method of claim 81, further comprising: a compact set of pulsed mirror coils wound around constrictions in the passages between the first and second formation sections and each of the first and second divertors.