Plasma containment apparatus comprising rotating and fixed magnetic fields

摘要

923,016. Thermonuclear apparatus; discharge apparatus. UNITED KINGDOM ATOMIC ENERGY AUTHORITY. Feb. 1, 1962 [Feb. 9, 1961], No. 4891/61. Classes 39 (1) and 39 (4). Plasma confinement apparatus comprises a vessel for containing a gas at low pressure, means for producing a radio-frequency rotating magnetic field within the vessel, and means for producing a stationary magnetic field within the vessel normal to the rotating magnetic field, the arrangement being such that the electrons in the plasma, but not the ions, rotate with the rotating field thereby constituting a current which reacts with the stationary field to concentrate the plasma away from the walls of the vessel. The angular rotation frequency # of the rotating field should be much greater than the ion cyclotron frequency and much less than the electron cyclotron frequency for that field, and the strength B of the field should be such that 2 (ne #/B)SP2/SP 1, where n is the number of ions per unit volume, e is the electronic charge, and # is the resistivity of the plasma. The strength of the stationary field B 0 should preferably be such that N 0 e# B 0 , where No is the total number of electrons per unit length of the plasma. In the apparatus shown in Fig. 5, a glass tube 1 is surrounded by coils 8, 9 which produce a stationary axial field. A field perpendicular to the axis and rotating about the axis is produced by two pairs of parallel copper bars 2 and 3 joined at one end and arranged in mutually perpendicular planes to form a two-phase winding energized from capacitor banks 4 and 5 through spark gaps 6 and 7. The 90 degrees phase difference between the currents in the two windings is produced by firing one spark gap “ cycle after the other. It is suggested that loss of particles at the ends of the tube could be prevented by magnetic fields of the " magnetic bottle " type or by making the apparatus toroidal. In an experimental apparatus the vessel was filled with argon, xenon, neon, or helium at pressures of 1-50 microns.