US2961557A - Apparatus for creating by induction an electric discharge in a gas at low pressure - Google Patents

Apparatus for creating by induction an electric discharge in a gas at low pressure Download PDF

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Publication number
US2961557A
US2961557A US740644A US74064458A US2961557A US 2961557 A US2961557 A US 2961557A US 740644 A US740644 A US 740644A US 74064458 A US74064458 A US 74064458A US 2961557 A US2961557 A US 2961557A
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United States
Prior art keywords
discharge
winding
sheath
current
inductor
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Expired - Lifetime
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US740644A
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English (en)
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Hubert Pierre
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Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
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Commissariat a lEnergie Atomique CEA
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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H1/00—Generating plasma; Handling plasma
    • H05H1/02—Arrangements for confining plasma by electric or magnetic fields; Arrangements for heating plasma
    • H05H1/10—Arrangements for confining plasma by electric or magnetic fields; Arrangements for heating plasma using externally-applied magnetic fields only, e.g. Q-machines, Yin-Yang, base-ball
    • H05H1/12—Arrangements for confining plasma by electric or magnetic fields; Arrangements for heating plasma using externally-applied magnetic fields only, e.g. Q-machines, Yin-Yang, base-ball wherein the containment vessel forms a closed or nearly closed loop
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E30/00—Energy generation of nuclear origin
    • Y02E30/10—Nuclear fusion reactors

Definitions

  • the invention relates to apparatus for creating by electromagnetic induction a high discharge current in a gas contained under low pressure in a tubular chamber closed upon itself, that is to say of doughnut shape, and preferably of toroidal shape.
  • the object of the present invention is to improve the stabilizing of this discharge in such a manner as to prevent any contact of the ionized gas or plasma with the walls of the chamber, which contact would result in a soiling of the plasma by evaporation of the material of which said walls are made.
  • Such a stabilizing permits of reducing the causes of cooling of the plasma and consequently of increasing the temperature obtained therein. It is known that the production of such a discharge constitutes one of the means for obtaining a controlled thermonuclear fusion in order to supply a considerable amount of energy.
  • the Smith apparatus (Physical Review, 1947, 71, 135), which makes use of the stabilizing properties of a metal lic tore surrounding the discharge, said tore being provided with a radial insulating cut to prevent shortcircuiting the driving electro-motive force.
  • annular discharge tube the wall of which is constituted by, or preferably lined with, a sheath of a conducting material provided with at least one insulating cut, along which wall is wound a stabilizing winding connected with a source of direct current, the turns of said winding being disposed substantially in planes perpendicular to the central line of said chamber.
  • the inductor winding is advantageously constituted by a conductor connected with a source capable of supplying within a very short time a high electrical energy, the turns made by said conductor being disposed substantially in planes parallel to the center line of the annular chamber.
  • the shape of the tubular chamber in which the discharge is produced is not critical. It is sufficient to have this chamber constituted by a tube closed upon itself and which does not include portions that are too sharply curved. In the following description, this shape will be called a doughnut shape.
  • this tube is of toroidal shape.
  • This tube is preferably made of a material which is gastight, is a good insulator, can be perfectly degassed and is as refractory as possible.
  • the glass known under the trade-name of Pyrex, porcelain and vitrified silica are particularly suitable.
  • this chamber permits of distributing the potentials in the vicinity of the insulating cut provided in the conductor sheath and therefore of preventing arcs between these lips.
  • Said sheath disposed on the outside of the insulating wall of the tube (when such a tube is provided) conforms to the shape of this wall as closely as possible.
  • said out is preferably covered by a local annular strip of conducting material, for instance in the shape of a portion of a metallic tore, electrically insulated from the conductor sheath.
  • Said conductor sheath may be made, for instance, by winding about the annular chamber a copper braid so as to form two crossed layers connected by welds. It is also possible merely to use a suitable shaped metal sheet, the metal that is chosen being then as good an electrical conductor as possible (aluminium, copper).
  • the whole of the annular chamber and of the conductor sheath may also be made in the form of a metal tore the inner wall of which is enamelled.
  • the advantage of the conductor sheath of shield is that any deformation of the plasma filament causes the formation in said sheath of induced currents which create a magnetic field exerting on the plasma a force which opposes said deformation.
  • the stabilizing winding is constituted by insulated conductor wires the turns of which are wound regularly about the annular tube in planes perpendicular to the center line thereof.
  • Such a stabilizing winding creates a longitudinal magnetic field parallel at any point to the discharge, that is to say to the plasma filament, which is confined along the central line of the chamber, due to the pinch effect created by the electromagnetic attraction between parallel current lines.
  • inductor winding it is preferably constituted by insulated conductor wires disposed regularly along the external surface of the-conductor sheath, the turns of this inductor winding being located substantially in" planes'parallel to the plane of the central line of the chamber and being advantageously disposed between the sheath and the stabilizing winding.
  • Said inductor winding consists of N elementary windingsconnected in parallel, each of these elementary windi'n'gs being constituted by a conductor forming it turns each adjoining the next one and covering a continuous annular band'o'f the external surface of the conductor sheath.
  • the number of turns it of each of said elementary windings is' chosen in such'm-anner as to adapt the source of current in the best conditions to the impedance of the inductor winding.
  • The'use of a plurality of elementary windings connected in'parallel permits of preventing deformations of the discharge having a wave length close to the length of the central line of the chamber (for instance contraction or expansion of the whole of the discharge).
  • the location of the inductor winding on the surface of the conductor sheath is preferred to thearrangement according to which the coupling of the discharge is ensured through a ferromagnetic core as in an ordinary transformer.
  • the natural self inductance of the discharge is reduced to aminimum, which permits of obtaining high current discharges without having to handle too high a reactive energy.
  • the mutual inductance between the discharge and the inductor Winding is maximum so that it is then possible to have a suflicient coupling even in the absence of a magnetic circuit; one might thus consider the possibility of working with a saturable magnetic circuit which would act only during a fraction of the cycle of operation.
  • I is the current in amperes in the discharge
  • P is the total number of electrically charged particles per centimeter of length of the discharge
  • K is the Boltzmann constant, equal to l.380 l0- ergs/ C.
  • T is the absolute temperature of the plasma in centigrade degrees.
  • the arrangements according to the present invention complete the stabilizing effect,'in particular for insufficient values of I.
  • the longitudinal field created by the stabilizing winding and also the fields due to the current circulating through the metal casing both have, in addition to their stabilizing action, the property of slowing down the diffusion of plasma toward the wall of the chamber when the electromotive force which'produces the pinch effect is reduced to Zero.
  • condition (I) is complied with as an average during every cycle, that is to say if:
  • the total longitudinal field existing between the plasma and the wall of the chamber may in some cases have a direction opposed to that created separately by the stabilizing winding, since the field due to the current induced in the metallic casing may have in some conditions a preponderating value: only the sum of these two effects is to be considered.
  • a magnetic circuit increasing the mutual inductance between the inductor winding and the discharge may have afavorable action.
  • This circuit might for instance be constituted by a'soft iron core surrounding at least a portion of the chamber, in a manner "analogous to the cores on which are wound the conventional inductor windings (Bostick et al.).
  • the plasma maintained by a system of electromagnetic forces, may be the seat of oscillations, either transient or not, giving rise to alternative compressions and expansions, for instance as a consequence of a tendency to instability.
  • oscillations induce in the inductor winding (or in another suitable winding) an electro- Emotive force which may be used to contribute in the heating of the plasma or to extract energy therefrom.
  • the apparatus according to the present invention has many advantages over those used up to this time to heat very rarefied gases to very high temperatures, and in particular:
  • the fact of making the inductor winding in the form of a plurality of elementary windings as above indicated may play, due to the stabilizing efiect it involves, a very important part in the case of discharges of very long duration (for instance .averaging of a second) for which it would not be possible to give the metal envelope a thickness corresponding to the skin thickness. This case might occur when :a temperature higher than thirty millions of degrees is obtained, for which the conductivity of the plasma will be higher than that of all known metals and in particular than that of the metal of which said envelope is made.
  • the feed of the stabilizing winding should be cut a short time t before the beginning :of the discharge, the value of this time t, which depends upon the speed of diffusion of the magnetic field through the metal envelope, being at most equal to
  • e is the thickness of the metal sheath and p the resistivity of the metal thereof in ohms per centimeter.
  • Fig. 1 diagrammatically shows a discharge according to the invention
  • Fig. 2 is a diametral vertical section of this apparatus with parts in cross section.
  • the annular chamber 3 is constituted by a toroidal envelope of Pyrex glass having a mean diameter of 78 cuts, the diameter of the circle the rotation of which forms the tore being equal to 8 cms.
  • This chamber is connected with a pumping conduit 4 of a diameter equal to 1.5 cm. itself connected with a pump capable of producing a vacuum ranging from 3 10- to 10" mm. of mercury.
  • This chamber 3 is covered with a conductor shield 5 made of a copper braid provided with a cut 6 the width (about 1 centimeter) of which corresponds substantially to one tenth of the diameter of the diameter of the above mentioned circle.
  • This cut is covered by a metal strip 7 insulated from shield 5.
  • the inductor winding 1 includes six conductors eadh constituted by a copper wire of 2 mm. diameter enclosed in a sheath of polythene of a diameter of about 1 cm. connected in parallel with the current source 8 and each of which makes four turns about the tore. The four turns of every conductor are adjacent to each other and occupy the portion of the external surface of the tore corresponding to an angle of 60.
  • the stabilizing winding 2 is constituted by four superimposed layers of enamelled copper wire of a diameter of 2 mm. These layers are wound in such manner that the respective magnetic fields they produce are added to one another but that the sum of the mutual inductance of one layer with the inductor winding and of the mutual inductance of the next layer with said inductor winding is practically zero.
  • wind wire 2 it suffices, in the example shown to wind wire 2 always in the same direction; for instance, supposing that the center line of chamber 3 (Le.
  • each turn of each layer is wound so that it runs upwardly, from below said plane to above it, on the outer portion of said turn and downwardly, from above said plane to below it, on the inner portion of said turn.
  • the envelope constituted by the stabilizing winding 2 is provided with a cut analogous to that provided in shield 5.
  • This cut must constitute an electrical insulation capable of supporting between its edges a potential difference equal (in this case 1L 4 induced by winding 1.
  • the source of current 8 includes a bank of condensers of 50 kv. and 60 microfarads fed by a high voltage generator. Its discharge is controlled by spark gap 11 having three electrodes and it is transmitted to the elementary inductor winding 1 through six coaxial cables 12 mounted in parallel, which ensures a better resistance to mechanical efforts and reduces the importance of the parasitic self-inductances due to the mounting.
  • a direct current source 13 constituted by a rotary machine of 600 v. and A. of usual type supplies current to the stabilizing Winding 2.
  • An observation window is constituted by a mere orifice of 5X20 mm. provided in shield 7 opposite the cuts, this window extending between the wires of winding 1 which are slightly spaced apart for this purpose.
  • an induction coil 14 capable of exciting an electrode 15 surrounding on the outside the pumping conduit 4, thus ionizing some particles of the gas circulating through this conduit.
  • auxiliary discharge established between electrodes passing through the wall of chamber 3, or also of electron-guns.
  • a pumping system 16 connected with conduit 4 permits of evacuating chamber 3, of degassing it and of introducing the desired gas thereinto.
  • An apparatus which comprises, in combination, a closed doughnut-shaped discharge tube containing a low pressure atmosphere of an ionizable gas, means for inducing a high discharge current to flow in said tube, a sheath of a conducting material closely surrounding the space inside said tube, said sheath being doughnut-shaped except for a transverse out between the ends thereof located opposite each other, a band of an insulating material filling said cut, a stabilizing winding surrounding said tube, each turn of said stabilizing winding being located in a plane substantially at right angles to the portion of the center line of said tube surrounded by said turn, and means for passing direct current through said'stabilizing winding, said current inducing means being independent of said sheath of conducting material.
  • An apparatus which comprises, in combination, a closed doughnut-shaped discharge tube containing a low pressure atmosphere of an ionizable gas, a sheath of a conducting material closely surrounding the space inside said tube, said sheath being doughnut-shaped except for a transverse cut between the ends thereof located opposite each other, a band of an insulating material filling said cut, at least one inductor winding wound on said sheath, the turns of said winding being located in respective planes parallel to the center line of said tube, a source capable "of releasing a high electrical energy within a short time, the terminals of said source being connected with those of said winding respectively, a stabilizing winding surrounding said sheath, each turn of said stabilizing winding being located in a plane substantially at right angles to the portion of the center line of said tube surrounded by said turn, and means for passing direct current through said stabilizing winding.
  • An apparatus including a plurality of such inductor windings disposed side by side on said sheath, said inductor windings being connected in parallel with said source, each of said inductor windings including a conductor forming a plurality of turns located side by side, all of said respective inductor windings having the same number of turns, the whole of the turns of said plurality of inductor windings covering the whole external surface of said sheath.
  • An apparatus further including an annular strip of a conducting material mounted around the ends of said sheath so as to surroundfsaid band of insulating material," said' strip being insulated from said sheath.
  • said stabilizing winding includes an even number of superirnposer layers of turns of a conductor, said layers being wound so that the respective magnetic fields they produce are added to one another but that the sum of the mutual inductance of one of said layer with said inductor winding and of the mutual inductance of the next of said layers with said inductor winding is practically zero, said layers stopping short of said cut in said sheath, on both sides of said cut.
  • An apparatus further including means for measuring the discharge current, said means including a current transformer surrounding one of the terminals of said source and a current transformer surrounding a portion of said discharge tube.
  • An apparatus which comprises, in combination, a closed doughnut-shaped discharge tube containing a low pressure atmosphere of an ionizable gas, means for inducing a high discharge current to flow in said tube, a sheath of a conducting material closely surrounding the space inside said tube, said sheath 'being continuous except for a transverse cut between the ends thereof, a band of an insulating material filling said cut, a stabilizing winding surrounding said tube, each turn of said stabilizing winding being located in a plane substantially at right angles to the portion of the center line of said tube surrounded by said turn, and means for passing direct current through said stabilizing winding, said current inducing means being independent of said sheath of conducting material.
  • An apparatus having inductor windings parallel to the axis of said tube and on said sheath, said windings disposed side by side on said sheath and connected in parallel with said source.
  • said inductor windings comprise a conductor forming a plurality of turns located side by side, all of said inductor windings having the same number of turns, the whole of the turns of said plurality of inductor windings covering the whole external surface of said sheath.

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  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Measuring Fluid Pressure (AREA)
  • Plasma Technology (AREA)
US740644A 1957-06-12 1958-06-09 Apparatus for creating by induction an electric discharge in a gas at low pressure Expired - Lifetime US2961557A (en)

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FR1180695T 1957-06-12

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US (1) US2961557A (fr)
BE (1) BE568261A (fr)
CH (1) CH350726A (fr)
FR (1) FR1180695A (fr)
GB (1) GB857686A (fr)
LU (1) LU36148A1 (fr)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3143477A (en) * 1959-06-02 1964-08-04 Csf Plasma confining device
US3174108A (en) * 1960-07-08 1965-03-16 Polytechnic Inst Brooklyn Pulse generating electrical circuit arrangements
US3255404A (en) * 1961-05-29 1966-06-07 Robert P Kidwell Electrical energy transmission system
US3318094A (en) * 1964-03-05 1967-05-09 Siemens Ag Alternating pinch plasma drive
DE1273713B (de) * 1960-12-23 1968-07-25 Atomic Energy Commission Vorrichtung zum immateriellen Einschliessen eines Hochtemperaturplasmas
US4180763A (en) * 1978-01-25 1979-12-25 General Electric Company High intensity discharge lamp geometries
EP0097161A1 (fr) * 1981-07-24 1984-01-04 Rodney John Truce Detection, mesure et application des parametres de contre-couronne sur un precipitateur electrostatique.

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3085058A (en) * 1959-12-08 1963-04-09 Bell Telephone Labor Inc Plasma heating
US6611106B2 (en) * 2001-03-19 2003-08-26 The Regents Of The University Of California Controlled fusion in a field reversed configuration and direct energy conversion

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2627552A (en) * 1946-01-05 1953-02-03 Gen Electric Resonator structure
US2640923A (en) * 1950-03-31 1953-06-02 Gen Electric System and apparatus for obtaining a beam of high energy electrons from charged particle accelerators
US2658999A (en) * 1951-01-05 1953-11-10 George M Farly Bevatron acceleration regulation
US2683216A (en) * 1946-01-31 1954-07-06 Bbc Brown Boveri & Cie Apparatus for accelerating charged particles by causing them to pass through periodically reversing potential fields
US2790902A (en) * 1954-03-03 1957-04-30 Byron T Wright Ion accelerator beam extractor

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2627552A (en) * 1946-01-05 1953-02-03 Gen Electric Resonator structure
US2683216A (en) * 1946-01-31 1954-07-06 Bbc Brown Boveri & Cie Apparatus for accelerating charged particles by causing them to pass through periodically reversing potential fields
US2640923A (en) * 1950-03-31 1953-06-02 Gen Electric System and apparatus for obtaining a beam of high energy electrons from charged particle accelerators
US2658999A (en) * 1951-01-05 1953-11-10 George M Farly Bevatron acceleration regulation
US2790902A (en) * 1954-03-03 1957-04-30 Byron T Wright Ion accelerator beam extractor

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3143477A (en) * 1959-06-02 1964-08-04 Csf Plasma confining device
US3174108A (en) * 1960-07-08 1965-03-16 Polytechnic Inst Brooklyn Pulse generating electrical circuit arrangements
DE1273713B (de) * 1960-12-23 1968-07-25 Atomic Energy Commission Vorrichtung zum immateriellen Einschliessen eines Hochtemperaturplasmas
US3255404A (en) * 1961-05-29 1966-06-07 Robert P Kidwell Electrical energy transmission system
US3318094A (en) * 1964-03-05 1967-05-09 Siemens Ag Alternating pinch plasma drive
US4180763A (en) * 1978-01-25 1979-12-25 General Electric Company High intensity discharge lamp geometries
EP0097161A1 (fr) * 1981-07-24 1984-01-04 Rodney John Truce Detection, mesure et application des parametres de contre-couronne sur un precipitateur electrostatique.
EP0097161B1 (fr) * 1981-07-24 1987-03-18 TRUCE, Rodney John Detection, mesure et application des parametres de contre-couronne sur un precipitateur electrostatique

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Publication number Publication date
FR1180695A (fr) 1959-06-08
LU36148A1 (fr)
CH350726A (fr) 1960-12-15
GB857686A (en) 1961-01-04
BE568261A (fr)

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