JPH0243924A - Isotope enrichment method, isotope enrichment device, isotope separation method and isotope separation device - Google Patents

Abstract

PURPOSE:To separate and recover an isotope by a method wherein a target substance is irradiated with high output laser to convert a part of the target substance to high density plasma and the electrons or ions generated in the plasma are allowed to collide with each other many times. CONSTITUTION:A turntable 16 is provided in an airtight container 10 and a secondary motor 18 is fixed to the turntable 16. A target holder 20 can be adjusted to an arbitrary direction in the airtight container 10 by the rotary actions different in their directions of the turntable 16 and secondary motor 18. A target substance 100 is placed and fixed to the front surface of the target holder 20. The laser beam from a laser source 24 is converged through an optical means 26 to irradiate the target substance 100 with high output laser. The generated electrons or ions collide with each other repeatedly to perform ionization.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is an isotope separation method and apparatus, particularly for separating isotope ions or isotopes with different mass numbers or atomic weights from an isotope separation target material using a laser. The present invention relates to an improved isotope separation method and apparatus for separating or recovering neutral atoms.

[Prior art] Separating isotope ions or isotope neutral atoms with different mass numbers from a target substance and obtaining an artificial abundance ratio different from the naturally occurring isotope ratio is performed using various mass spectrometry methods. Useful in concentration and other applications.

For these isotope separations, methods using lasers have been known and are practical.

Typically, such isotope separation involves externally applying energy to the atomic states of the target material to generate atomic particles from the target material, then exciting the desired isotope in the atomic particles, and further This is carried out by a step of ionizing the obtained isotope ions or isotope neutral atoms.

Conventionally, separate energy sources are used for each of the steps. That is, in order to generate atomic particles from the target material, the target material is irradiated with a relatively high energy beam such as an electron beam or an ion beam, or by heating the target material to a high temperature. be exposed.

And for the atomic particles obtained in this way,
In order to selectively excite specific isotope atoms, laser irradiation having a wavelength in a desired optical absorption band (isotope shift) is performed.

Then, in order to ionize the excited isotope ions or isotope neutral atoms, irradiation with ultraviolet rays or X-rays is performed, thereby separating and recovering isotopes with different mass numbers. becomes possible.

[Problem to be solved by the invention] However, as mentioned above, according to the conventional method,
It requires multiple separation steps for the target material, and the laser must be obtained from a laser source that oscillates at wavelengths in the optical absorption bands that are specific to only the specific selected isotope atoms, so that However, there is a problem in that a laser source with such an open wavelength must be separately prepared.

In particular, since the optical absorption band (isotope shift) determined by each isotope has a relatively narrow frequency range, there is a problem in that the oscillation wavelength of the laser must be precisely adjusted.

The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to easily separate and recover isotopic ions or isotopic neutral atoms with different f1m numbers or atomic weights from target substances. An object of the present invention is to provide an improved isotope separation method and apparatus that can perform the following steps.

[Means for Solving the Problems] In order to achieve the above object, the method according to the present invention places a target material in an evacuated and reduced pressure state, irradiates the target material with a high-power laser, and removes the target material from the target material. It is characterized by generating high-density plasma.

In the present invention, the generated electrons, ions, and neutral atoms in the plasma have an extremely high particle density, so they collide with each other many times, thereby forming an artificial isotope ratio different from the natural isotope ratio. A state of isotopic enrichment can be achieved, and isotopes with different mass numbers or atomic weights can be separated extremely easily.

The isotope separation apparatus according to the present invention includes: an airtight container that stores a target material therein and is evacuated by a constant pressure holding means; a holder that places and fixes the target material at a predetermined position in the airtight container; The holder includes a laser source that irradiates a high-power laser beam onto a target material in a pressure-reduced airtight container, and an optical system that guides the laser beam to the target material. Inside the plasma generated by the irradiation, electrons, isotope ions, and isotope neutral atoms are held in positions where they can collide with each other.

Therefore, according to the apparatus of the present invention, mutual collisions between electrons, ions, and neutral atoms in the airtight container in the generated high-density plasma are repeated multiple times, resulting in isotopically enriched ions or neutral atomic states. can be realized. This allows isotopes with different mass numbers or atomic weights to be easily separated.

Furthermore, according to another apparatus of the present invention, a separation and recovery section for recovering the isotopes separated as described above is provided in the reduced pressure airtight container, and isotopes having different mass numbers or atomic weights are separated. Separation and recovery can be easily performed.

FIG. 1 shows a separation apparatus for performing isotope separation according to the present invention, and the method and apparatus of the present invention will be explained in detail below based on FIG.

In the present invention, the airtight container 10 is made of a pressure-resistant sealed container and is equipped with constant pressure maintaining means. In the figure, this constant pressure maintaining means consists of a vacuum pump 12 and a pressure regulator 14.

Therefore, the airtight container 10 according to the present invention can evacuate its interior to a desired pressure and maintain this reduced pressure state.

A rotary table 16 is provided inside the airtight container 10, a secondary motor 18 is fixed to the rotary table 16, and a target holder 20 is fixed to the main shaft of the motor 18. Therefore, the target holder 20 is moved into the airtight container 1 by the rotating action of the rotary table 16 and the secondary motor 18 in different directions.
It becomes possible to arbitrarily adjust its position and direction within 0.

A target material 100 according to the present invention is placed and fixed on the front surface of the target holder 20.

In the present invention, a high-density plasma is generated from the target material 100 as described later, and by repeated mutual collisions of electrons, ions, and neutral atoms in this high-density plasma, a desired mass number or atomic weight can be achieved in the present invention. Since different isotopes are separated, the target holder 20 is provided at a position biased to one side within the airtight container 10 to ensure a sufficient space for high-density plasma to develop within the airtight container 10.

A laser entrance window 22 is formed in the airtight container 10, and a laser source 24 is provided facing the laser entrance window 22.

A laser beam LB generated from the laser source 24
The beam is focused through the optical system means 26 and irradiates the target material 100 with a high-power laser. The density of the laser beam irradiated onto the target material 100 in this manner can be arbitrarily controlled by adjusting the optical axis position of the optical system means 26.

In the present invention, in the airtight container 10, it is possible to further provide a separation and recovery section 28 extending into a region of high-density plasma 200 generated from the target material 100 by irradiation with the high-power laser, Collection section 28
Isotopes with different mass numbers or atomic weights generated by multiple repeated collisions between electrons, ions, and neutral atoms in the high-density plasma 200 are separated and recovered, and the isotopes artificially obtained by the present invention It is possible to find the ratio.

[Operation] Therefore, according to the present invention, the target material 100 is irradiated with a high-power laser, and as a result, a high-density plasma 200 is generated from the target material 100, and within this high-density plasma 200, electrons, Ions and neutral atoms repeatedly collide with each other multiple times, resulting in excitation and ionization within the plasma 200. In this way, the present invention simply applies a high-power laser to the target material 100. It is possible to form an artificial ratio that differs from the natural isotope ratio simply by irradiation and the formation of high-density plasma, which makes it possible to achieve an enriched state of isotopes and to very easily separate isotopes with different mass numbers or atomic weights. becomes possible.

[Effects of the Invention] As described above, according to the present invention, the generation, selective excitation, and separation of atomic particles necessary for isotope separation can be performed in a hermetic manner by only irradiation with a high-power laser. It becomes possible to carry out the process in a container, and it becomes possible to extremely simplify the apparatus and procedure.

Furthermore, in the laser irradiation of the present invention, the wavelength of the laser beam can be determined regardless of the optical absorption band region of the isotope that needs to be separated as in the conventional method, so there is no need for precise wavelength adjustment as in the conventional method. There is an advantage.

Furthermore, the apparatus of the present invention only needs to be provided with an airtight container, a laser source, an optical system means, and a holder for fixing and holding the target material in the airtight container, and can be used to generate, selectively excite, and ionize atomic particles as in the conventional method. This method has the advantage that the equipment required for each step can be removed, and there are no restrictions on the target material.

Furthermore, in the present invention, by providing a separation and recovery section for separated isotopes in the airtight container, it becomes possible to measure necessary isotope ratios and other values extremely easily.

[Example code] Preferred embodiments of the present invention will be described below.

Embodiment 1 In FIG. 1, an Nd+YAGQ switch laser is used as the laser 24, and a second wavelength is used as the laser 24.
Using harmonics of 532 nm (pulse width 10 nanoseconds), the irradiation laser power density was set to 109 to 1011 W/cm,
Table 1 shows an example in which Ni was used as the target material 100 while the internal pressure of the container 10 was evacuated to 10-'' to 10-7 Torr (measured with Ni+).

Table 1 It is understood that concentration of 6ON and 62Nl occurred in this example.

Example 2 In FIG. 1, a KrF excimer laser is used as the laser 24, a wavelength of 248nα (pulse width 15 nanoseconds), and an irradiation laser power density of 10 to 1010 W/
crA2, and the internal pressure of the container 10 is 10' to 10-7
Table 2 shows an example using Nj as the target material 100 while evacuation to Torr (measured with Ni+).

Table 2 It is understood that

Example 3 In FIG. 1, an Nd:YAGQ switched laser is used as the laser 24, a second harmonic wave of 532 nm (pulse width 10 ns) is used as the wavelength, the irradiation laser power density is set to 10'' to 1011 W/cm+2, and the internal pressure of the container is Table 3 shows an example in which carbon (C) was used as the target material while being evacuated to 10-5 to 10-7 Torr (measured at C+).

Table 3 According to this example, concentration of Ni occurred. Example 4 Figure 2 shows another specific example of the separation device according to the present invention, and the same members as in Figure 1 are given the same reference numerals. The explanation will be omitted.

The characteristic feature of this embodiment is that the separation and recovery section 28
is shown in detail, and this separation and recovery section 28
is the ion trap electrode 30. It includes an electromagnet 32 for separating ions and neutral atoms, an ion collector 34, and a neutral atom trap 36. As mentioned above, the target material 100
When the target material 1 is irradiated with the high-power laser LB,
A high-density plasma 200 is generated from 00, and within this plasma 200, electrons, ions, and neutral atoms repeatedly collide with each other multiple times. The ions and neutral atoms are mixed in this plasma 200, and in the embodiment shown in FIG. 2, separation and recovery are performed in each of the sections.

That is, a DC electric field is applied to the electrostatic ion trap electrode 32, and when ions i and neutral particles n pass through this field, the ion i is deflected in its traveling direction. On the other hand, it has no effect on neutral particles n.

In the embodiment, a separation electromagnet 32 is further arranged downstream of the ion trap electrode 30, and this electromagnet 32
Further, the ion i is deflected by the magnetic field generated by the ion i.

Therefore, the traveling direction of the ions i is restricted by the trap 30 and the electromagnet 32, and current is collected by the ion collector 34. Ions already have an isotopic ratio different from that in nature due to multiple collisions between electrons and ion atoms in high-density plasma 200 (isotope enrichment has been achieved), so ions and neutral Isotopic enrichment is performed on the ion collector 34 only by separating atoms.

Further, by providing the slit 38 at a position determined for a specific isotope that requires current collection, it is also possible to separate only the specific isotope.

Neutral particles, particularly neutral atoms, from which the ions i have been separated in this way travel almost straight through the separation and collection section 28 and are captured by the neutral atom trap 36.

As described above, it is understood that according to this embodiment, a specific isotope is collected in the ion collector 34, and as a result, isotope enrichment is performed.

In the present invention, the abundance ratio of the ion i in the plasma 200 is different from the abundance ratio in nature, and in this way, isotope enrichment is performed by isotope separation and recovery.

Embodiment 5 FIG. 3 shows still another embodiment of the isotope separation apparatus according to the present invention, and the same members as those in the above-mentioned figures are given the same reference numerals and the explanation thereof will be omitted.

A characteristic feature of this embodiment is that the separation and recovery unit 28 separates neutral atoms generated from the target material 100 by the laser irradiation of the present invention and neutral atoms thermally emitted from the target material 100. This method utilizes the difference in velocity components possessed by each neutral atom.

That is, as described above, according to the present invention, the high-density plasma 200 is generated by irradiating the target material 100 with the high-power laser LB, and at this time, neutral atoms are ionized once in the high-density plasma 200. but,
It recombines with the high concentration of electrons present in the high density plasma 20θ and is immediately neutralized.

On the other hand, thermally neutral atoms are also emitted from the target material 100 at the same time, and these thermally emitted neutral atoms generate noise components for the separation and recovery in the present invention, and these are removed. This is desirable.

In this embodiment, since the desired neutral atoms and the thermally neutral atoms in the high-density plasma have different velocity components, the separation action can be performed with this point in mind.

That is, in this embodiment, the separation and collection section 28 has a high-speed shutter 40, and this high-speed shutter 40 is connected to the laser LB.
The opening and closing of the high-density plasma 200 is controlled in synchronization with the generation of the high-density plasma 200 induced by the high-density plasma 200.
Only isotope ions and isotope neutral atoms with a specific velocity component in zero are allowed to pass through. Therefore, the high speed shutter 40
The ions and neutral atoms that have passed through are only the separated isotopes necessary for the present invention, and although this is not explained in detail, the collector 42 shown in the embodiment of FIG. It becomes possible to collect it.

In this embodiment, apertures can be installed before and after the high-speed shutter 40, and according to the embodiment, an aperture 44 is provided in front of the high-speed shutter 40.

In the embodiments described above, the target material is shown as a solid, but in the present invention, it is also possible to use such a target material by adsorbing gas or liquid onto the surface of another solid, and of course, these materials can also be used. gas, liquid,
The solid target material can also be a compound.

[Brief explanation of the drawing]

Fig. 1 is a schematic explanatory diagram of the apparatus of the present invention to which the method according to the present invention is applied; It is a schematic explanatory view of the present invention apparatus provided with yet another separation and recovery device according to the invention. 10...12...14...20...24...26...28...100...200...L B... Airtight container Vacuum pump pressure regulator target holder Laser source optical system means Separation and recovery section Target material High-density plasma laser beam Applicant Toyota Central Research Institute Co., Ltd. Agent Patent attorney Yoshi 1) Kenji [8-721X trial 4 Figure 2 Figure 1

Claims (3)

[Claims] (1) Place the isotope-separated target material in a vacuum container, irradiate the target material with a high-power laser, turn at least a portion of the target material into high-density plasma, and generate electrons, ions, and An isotope separation method characterized by separating isotopes with different mass numbers at an artificial ratio different from the natural isotope ratio by colliding neutral atoms with each other many times. (2) An airtight container equipped with a constant pressure holding means that maintains the internal pressure at a predetermined reduced pressure state, and an isotope separation target material placed in the airtight container, and a high-density plasma generated from the target material in the airtight container. a target holder provided in an airtight container so that electrons, ions, and neutral atoms can collide with each other many times, a high-power laser source, and optical system means for irradiating the target material with the laser, An isotope separation device characterized in that atomic particles are generated from a target material, excited and separated in an airtight container to separate isotopes with different mass numbers. (3) An airtight container equipped with a constant pressure holding means that maintains the internal pressure at a predetermined reduced pressure state, and an isotope separation target material placed in the airtight container, and a high-density plasma generated from the target material in the airtight container. a target holder disposed in an airtight container so that electrons, ions, and neutral atoms can collide with each other many times; a high-power laser source; an optical system means for irradiating the target material with the laser; a separation and recovery unit installed in the plasma to separate and recover ions and neutral atoms in the plasma, and generate atomic particles from the target material and excite and separate them in an airtight container to generate artificial isotopes different from natural isotopes. An isotope separation device characterized by separating and recovering isotopes with different mass numbers at a certain ratio.