US3558960A - Switching device - Google Patents

Switching device Download PDF

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Publication number
US3558960A
US3558960A US779341A US3558960DA US3558960A US 3558960 A US3558960 A US 3558960A US 779341 A US779341 A US 779341A US 3558960D A US3558960D A US 3558960DA US 3558960 A US3558960 A US 3558960A
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Prior art keywords
anode
cathode
gas
electrode
switching device
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Expired - Lifetime
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US779341A
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English (en)
Inventor
Gunter A G Hofmann
Ronald C Knechtli
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Raytheon Co
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Hughes Aircraft Co
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Publication date
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J17/00—Gas-filled discharge tubes with solid cathode
    • H01J17/02—Details
    • H01J17/14—Magnetic means for controlling the discharge

Definitions

  • SWITCHING DEVICE BACKGROUND This invention is directed to a switching device of the crossed field type, employing Penning discharge, wherein regulation of the magnetic field strength controls electron path length so that this path length is above or below a critical value.
  • Switching devices of a general type are, known in the art. Penning US. Pat. No. 2,I82,736 describes such a switching device, while Boucher, et al. U.S. Pat. No. 3,2l5,893 and Boucher, US. Pat. No. 3,2l5,939 describe improvements thereon. All three of these devices are primarily directed to rectifier type switching, and the Boucher and Boucher, ct al. patents are directed to an improvement wherein the shape of the magnetic field improves rectifying action by providing a lower breakdown voltage in one direction than the other between the two electrodes which form the gas-filled space.
  • the device includes a gas supply which will maintain the gas pressure in the interelectrode space within operational limits.
  • the electrodes are tubular and concentrically positioned, with the gas reservoir positioned interiorly of the inner tubular electrode, with radial openings through the tubular inner electrode walls to connect the gas reservoir with the interelectrode space.
  • a switching device of the crossed field type suitable for high current capacity and long conduction periods. It is a further object to provide a switching device which has a gas reservoir therein to maintain the gas at a proper pressure. It is another object to provide a crossed field switch having a concentric tubular anode and cathode with a gas reservoir interiorly of the interior electrode. It is still another object to employ tubular electrodes in a crossed field switching device, with the inner electrode being radially perforated and with the gas reservoir interiorly thereof so that the radial perforations provide for equalization of gas pressure and proper maintenance of gas pressure in the interelectrode space.
  • FIG. 1B is a schematic drawing of another portion of such a power system.
  • the switching device is generally indicated at 10 in FIG. 2.
  • power source 12 drives generator 14.
  • Power source l2 can be of any conventional type, including hydroelectric, internal combustion engine, or steam, including nuclear heated steam.
  • Generator 14 generates alternating cur rent electricity of suitable voltage and frequency for that portion of the system. It supplies alternating current transformer [6 which changes the voltage to one suitable for rectification and direct transmission. When direct current is employed for economic, long distance power transmission, this usually requires an increase in voltage at the transformer output, as compared to its input.
  • Transformer l6 supplies rectifier 9,
  • the switch device 10 comprises housing 30 which is carried upon bottom flange 32.
  • Bottom flange 32 is in turn mounted upon base flange 34, and they are secured together to provide a tight seal.
  • Base flange 34 stands upon foot 36 for supporting the switch device structure.
  • vacuum connection 38 is connected to base flange 34 for drawing a suitable vacuum on the interior of housing 30 and then letting into the tube the desired gas (e.g. hydrogen, including its isotope deuterium) at the required pressure.
  • Housing 30, together with bottom flange 34 serves as a suitable vacuum tight envelope.
  • Cathode 40 is in the form of a cylindrical tube. It is spaced inwardly from housing 30. Cathode 40 has a lower cap 42 by which it is supported from base flange 34 by means of standoff 44. Lower cap 42 does not need to effect closure, but simply provides mechanical support for the cathode and reduces plasma end losses. By this construction, the entire cathode can be withdrawn through the large opening in bottom flange 32 when the flanges are separated for inspection and service of the cathode and inspection and service of the interior of housing 30.
  • Cathode 40 is metallic and can be made of stainless steel. The cathode is connected to the foot 36 such as by a metallic strip. Thus, foot 36 provides one of the electrical connections to the switching device l0.
  • Cathode 40 preferably has an axial slot to prevent the circumferential circulation of current during switching transients, when the axial magnetic field changes with time.
  • Anode 46 is of cylindrical tubular construction and is positioned concentrically with cathode 40 to provide a radial space therebetween having the dimension d.
  • The'radial space d is substantially equal at all facing positions of the anode and cathode.
  • Housing 30 has a top cap 48 upon which anode 46 is positioned.
  • the anode is maintained in position by employing anode cap 50 which is secured to the cylindrical anode 46, and in turn carries mounting stud 52.
  • Mounting stud 52 provides both mechanical support by being secured to housing cap 48, and provides electrical continuity through the cap by connector 54.
  • anode cap 50 is spaced below top cap 48 and connector 54 passes through insulative mounting stud 52 so that connector 54 and the entire anode are electrically separated from the housing.
  • top cap 48 can be of insulative material.
  • Anode 46 has a plurality of holes 56 therethrough so that the interior space within anode 46 is in communication with the interelectrode space.
  • the volume within the interior of anode 46 is preferably in the order of l times the volume in the interelectrode space.
  • Magnet 58 is positioned on the exterior of housing in such a manner as to provide magnetic lines of force in the interelectrode space which are substantially parallel to the axis of the electrodes of switching device l0 over at least part of the electrode length.
  • Magnet 58 is illustrated as being an electromagnet, and such is preferred so that the magnetic field can readily be switched on and off.
  • the power supply to magnet 58 is preferably of such nature as to provide for rapid turn on and off of the field. lts strength is such as to provide a field between 25 and ISO Gauss; 70 Gauss was found to be a preferred value for the dimensions given below used in our experiments to date, considering the turn on and turn off effects, as well as magnet power consumption.
  • anode 46 As well as the interelectrode space, is filled with a gas to an appropriate pressure.
  • the Paschen curve is shown therein. This curve illustrates that at a certain critical product of the interelectrode pressure p times the interelectrode spacing d, the voltage to breakdown is fairly low. It also illustrates at point A that for a lower product, voltage to cause breakdown is considerably higher. This is because at lower pressure, the electron meanfree path exceeds the interelectrode spacing d, and the ionization rate decreases, which makes it more difficult to sustain the discharge and makes it possible to withstand higher voltage between electrodes before breakdown occurs.
  • holes 56 in anode 46 permit the space interiorly of anode 46 to communicate with the interelectrode space.
  • the gas within the interior of anode equalizes pressure with the gas in the interelectrode space through holes 56.
  • holes are necessary rather than attempting equalization around the ends of the anode tube.
  • a charge of 0.4 Coulombs is approximately sufficient to reducethe interelectrode space gas pressure to a point where the switching device will off switch, due to gas loss.
  • a charge greater than 2.4 Coulombs can be passed before the gas pressure decreases sufficiently to cause danger of off switching.
  • the conduction period can be further extended by providing an auxiliary gas source such as titanium hydride ribbon or sponge 60 at an appropriate temperature, inside of the anode volume or in communication with it.
  • auxiliary gas source alone, without the holes providing fast communication for the gas between the interelectrode volume and the gas-filled volume inside the anode, would not suffice to prevent self-interruption of the gas discharge due to gas depletion in the interelectrode space under passage of a high current. Under such conditions, the time constant of a conventional auxiliary gas source would be too long compared to the gas depletion time constant of the interelectrode space. In this example, a magnetic field in the order of 70 Gauss is provided in the interelectrode space.
  • the holes 56 in the anode do not limit current-carrying capacity, because discharge is cathode area limited, rather than anode area limited.
  • the switching device I0 is capable of off switching DC loads of L000 amperes, and hold off 25 kilovolts within a recovery time on the order of about 25 microseconds. Thus, it is useful as a DC switch or element ofa DC circuit breaker, as illustrated in FIGS. lA and IB.
  • a switching device comprising:
  • An envelope arranged to maintain a subatmospherie pressure within said envelope, gas at a subatmospheric pressure within said envelope;
  • cathode electrode within said envelope, said cathode electrode having an active cathode face;
  • an anode electrode positioned within said envelope, said anode electrode having an active anode face facing said active cathode face, and defining an interelectrode space;
  • said anode and said cathode are each cylindrical tubes, said cylindrical tubes of said anode and said cathode each having an axis, said axes being substantially coincident, the interelectrode space being measured in a distance perpendicular to said axes, and the electric field being applied in a direction perpendicular to said axes, said magnetic field being applied in a direction substantially parallel to said axes.

Landscapes

  • Plasma Technology (AREA)
  • Lasers (AREA)
  • Discharge Lamp (AREA)
  • Switches That Are Operated By Magnetic Or Electric Fields (AREA)
US779341A 1968-11-27 1968-11-27 Switching device Expired - Lifetime US3558960A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US77934168A 1968-11-27 1968-11-27

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US3558960A true US3558960A (en) 1971-01-26

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Application Number Title Priority Date Filing Date
US779341A Expired - Lifetime US3558960A (en) 1968-11-27 1968-11-27 Switching device

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US (1) US3558960A (de)
JP (1) JPS4823744B1 (de)
CH (1) CH502027A (de)
GB (1) GB1278972A (de)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3678289A (en) * 1971-08-18 1972-07-18 Hughes Aircraft Co Magnetic field control circuit for crossed field switching devices
US3735197A (en) * 1971-08-13 1973-05-22 V Pakin Rectifier
US3769537A (en) * 1972-09-14 1973-10-30 Hughes Aircraft Co Baffle for perforated electrode in a crossed-field switch device
DE2819111A1 (de) * 1977-05-17 1978-11-23 Hughes Aircraft Co Gasentladungs-schaltroehre mit gekreuzten feldern und verfahren zum einschalten einer solchen schaltroehre
WO2005008298A3 (en) * 2003-07-14 2005-04-28 David M Tillstrom Eyeglass strap retainer device
US9330876B2 (en) 2013-11-06 2016-05-03 General Electric Company Systems and methods for regulating pressure of a filled-in gas
US9557009B2 (en) 2013-11-06 2017-01-31 General Electric Company Gas reservoir and a method to supply gas to plasma tubes

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2528547A (en) * 1945-08-03 1950-11-07 Gerard J Reilly Hydrogen thyratron
US2684461A (en) * 1951-03-06 1954-07-20 Era Patents Ltd Direct current electric transmission system
US3014857A (en) * 1958-09-02 1961-12-26 James D Gow Plasma device

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2528547A (en) * 1945-08-03 1950-11-07 Gerard J Reilly Hydrogen thyratron
US2684461A (en) * 1951-03-06 1954-07-20 Era Patents Ltd Direct current electric transmission system
US3014857A (en) * 1958-09-02 1961-12-26 James D Gow Plasma device

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3735197A (en) * 1971-08-13 1973-05-22 V Pakin Rectifier
US3678289A (en) * 1971-08-18 1972-07-18 Hughes Aircraft Co Magnetic field control circuit for crossed field switching devices
US3769537A (en) * 1972-09-14 1973-10-30 Hughes Aircraft Co Baffle for perforated electrode in a crossed-field switch device
DE2819111A1 (de) * 1977-05-17 1978-11-23 Hughes Aircraft Co Gasentladungs-schaltroehre mit gekreuzten feldern und verfahren zum einschalten einer solchen schaltroehre
WO2005008298A3 (en) * 2003-07-14 2005-04-28 David M Tillstrom Eyeglass strap retainer device
US9330876B2 (en) 2013-11-06 2016-05-03 General Electric Company Systems and methods for regulating pressure of a filled-in gas
US9557009B2 (en) 2013-11-06 2017-01-31 General Electric Company Gas reservoir and a method to supply gas to plasma tubes

Also Published As

Publication number Publication date
CH502027A (de) 1971-01-15
DE1958047B2 (de) 1972-09-21
JPS4823744B1 (de) 1973-07-16
GB1278972A (en) 1972-06-21
DE1958047A1 (de) 1970-06-11

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