US3674634A - Plasma confinement apparatus - Google Patents

Plasma confinement apparatus Download PDF

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Publication number
US3674634A
US3674634A US792553*A US3674634DA US3674634A US 3674634 A US3674634 A US 3674634A US 3674634D A US3674634D A US 3674634DA US 3674634 A US3674634 A US 3674634A
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United States
Prior art keywords
plasma
field
frequency
power
toroidal
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Expired - Lifetime
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US792553*A
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English (en)
Inventor
Christopher John Hamilt Watson
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UK Atomic Energy Authority
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UK Atomic Energy Authority
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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
    • H05H1/16—Arrangements for confining plasma by electric or magnetic fields; Arrangements for heating plasma using externally-applied electric and magnetic fields
    • 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 plasma confinement apparatus.
  • thermonuclear power for example, it is necessary to device means for confining a hot plasma of thermonuclear fuel without the plasma coming into contact with material boundaries.
  • the means for confining the hot plasma should not consume more power than can be secured from thermonuclear reactions in the contained plasma.
  • the invention provides a plasma confinement apparatus comprising a vessel for containing a gas at low pressure, means for forming in or introducing into the vessel a plasma, means for producing a static magnetic field te'nding to confine the plasma, means for producing a raido frequency electromagnetic field which moves relatively to the plasma faster than the ions in the plasma are moving, the frequency of the electromagnetic field being in the region of l megahertz, the said means for producing the radio frequency electromagnetic field including an electrical conductor forming an endless path for conducting electrical or electromagnetic power, which path has a distributed inductance and capacitance such that it is a circuit which resonates at the frequency of the electromagnetic field.
  • conductors used to localise the field may comprise subdivided electrically conducting wires within which volume currents flow.
  • the vessel is toroidal.
  • the electrical conductor forming the endless conducting path comprises a closed toroidal helix encompassing the vessel.
  • the electrical conductor is formed by forming the vessel with an electrically insulating surface, depositing a thin layer of metal on the surface and cutting a groove or grooves through the metal layer, the groove or grooves following the required direction of the conducting path.
  • FIG. 1 is a diagrammatic illustration of part of the apparatus
  • FIG. 2 is a diagrammatic part sectional view of the apparatus.
  • the plasma illustrated at 11, is contained within a torus 12.
  • the construction of such an apparatus and means for forming a plasma within the torus are described, for example, in US. Patent No. 3,054,742 the US. counterpart of British patent specification No. 830,252.
  • Means for generating a static magnetic field has been shown diagramatically as winding 18 fed by a conventional D.C. supply 19.
  • the low frequency RF confinement system of this example has to meet the following requirements (i) the electrical energy has to be localised in the same region of space as the magnetic energy and not stored expensively elsewhere; (ii) a large fraction of the confinement has to be effected by a static magnetic field, and (iii) the Q of the circuit has to be raised by many orders of magnitude above those achieved in existing radiofrequency confinement systems.
  • the circuit must be designed so that retardation elfects are important and hence, since the vacuum wavelength at 1 mc./s. is much larger than reactor dimensions, it must take the form of a slow wave structure, wrapped around the plasma.
  • the second requirement implies that the ion cyclotron frequency (2 in the static magnetic field would inevitably exceed 1 mc./s. This creates a geometric problem, since RF fields can freely propagate through a plasma along magnetic lines of force at frequencies w below 9 and consequently exert no pressure on it. This geometric problem is solved in this example by employing a toroidal magnetic field topology.
  • the third requirement involves special precautions to minimise both ohmic and radiative loss.
  • the configuration of the conductor for localising the RF field in the apparatus of this example comprises a closed toroidal helix electrical conductor represented diagrammatically in FIG. 1 at 13. This is a slow wave structure which permits RF power at any time of a discrete set of resonant frequencies to circulate repeatedly around the toroidal helix, until the power is dissipated by ohmic and/or radiation losses.
  • the field structure at these frequencies is ideally suited to plasma confinement, since both the electric and magnetic fields have minima on the circular axis of the torus and form a time-averaged minimum well in the electric and magnetic fields. It is believed that the toroidal helix arrangement of this example may have a Q as high as 10 at a frequency of 1 mc./s.
  • the RF system of this example combined with (for example) a simple toroidal l/R static magnetic field to provide the main confining force, can lead to a reactor having the following approximate parameters. It
  • RF power required P 5 10
  • P p is the ratio of the RF pressure to the plasma pressure
  • RF V is the ratio of the volume occupied by the RF field to that of the plasma.
  • the torus 12 comprises an electrically insulating shell 14, on top of which is deposited a layer of metal 14a of the order of 1 millimetre thick.
  • a helical groove 15 is cut through the metal layer to leave a helical conductor 13a.
  • FIG. 1 A technique for coupling RF power into the closed helical conductor 13 is illustrated in FIG. 1.
  • a separate conductor 17, insulated from the helical conductor 13, is wound around adjacent a few turns of the helical conductor 13, thus providing a close electromagnetic coupling into conductor 13 for RF power fed into conductor 17.
  • the invention is not restricted to the details of the foregoing example.
  • One such other configuration envisaged for the conductor is that of a generalised tennis ball scam in which the closed loops along which the waves are guided lie on the surface of a sphere and have a number of symmetrically arranged lobes, giving rise to an approximately multipole field configuration Within.
  • This arrangement has the advantage over the toroidal helix of allowing a significantly more favourable surface to volume ratio (and hence lower minimum plasma pressure).
  • a normal tennis ball seam would probably have an unacceptably low radiation Q, so a more convoluted configuration is required.
  • a difficulty lies in the choice of the accompanying static magnetic field.
  • a magnetic mirror field can be excluded: it is necessary to envisage a topologically toroidal field, for example that created by a straight current-bearing conductor passing through the centre, or that of a magnetohydrodynamic Hill vortex.
  • the foregoing example has, effectively, subdivided electrically conducting wires for providing the endless toroidal conducting path. It is envisaged that the toroidal conducting path may, for example, be alternatively provided by a toroidal waveguide.
  • a plasma confinement apparatus comprising a vessel for containing a gas at low pressure, means for producing a static magnetic field tending to confine the plasma, means for producing a radio frequency electromagnetic field which moves relatively to the plasma faster than the ions in the plasma are moving, the frequency of the electromagnetic field being in the region of 1 megahertz, the said means for producing the radio frequency electromagnetic field including an elongated electrical conductor wrapped around the plasma and forming an endless path for conducting electrical or electromagnetic power, which path has a distributed inductance and capacitance such that it is a circuit which resonates at the frequency of the electromagnetic field.

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  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Particle Accelerators (AREA)
  • Plasma Technology (AREA)
US792553*A 1968-05-22 1969-01-21 Plasma confinement apparatus Expired - Lifetime US3674634A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB2454768 1968-05-22

Publications (1)

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US3674634A true US3674634A (en) 1972-07-04

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US792553*A Expired - Lifetime US3674634A (en) 1968-05-22 1969-01-21 Plasma confinement apparatus

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US (1) US3674634A (enrdf_load_stackoverflow)
GB (1) GB1252762A (enrdf_load_stackoverflow)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3886402A (en) * 1974-05-07 1975-05-27 Us Energy Magnetic pumping in spatially inhomogeneous magnetic fields
GB2425880A (en) * 2005-05-05 2006-11-08 Christopher Strevens Thermonuclear fusion reactor using radio frequency containment in a solenoidal toroid
US20110127856A1 (en) * 2008-07-23 2011-06-02 Georges Lochak Magnetic monopole accelerator
US9816481B2 (en) 2012-10-26 2017-11-14 William Paul SULLIVAN System and apparatus for generating electricity from motion of fluid

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117075354A (zh) * 2023-09-14 2023-11-17 上海交通大学 产生高对比度相对论涡旋光的装置及空间波前诊断方法

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3886402A (en) * 1974-05-07 1975-05-27 Us Energy Magnetic pumping in spatially inhomogeneous magnetic fields
GB2425880A (en) * 2005-05-05 2006-11-08 Christopher Strevens Thermonuclear fusion reactor using radio frequency containment in a solenoidal toroid
US20110127856A1 (en) * 2008-07-23 2011-06-02 Georges Lochak Magnetic monopole accelerator
US9816481B2 (en) 2012-10-26 2017-11-14 William Paul SULLIVAN System and apparatus for generating electricity from motion of fluid

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Publication number Publication date
GB1252762A (enrdf_load_stackoverflow) 1971-11-10

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