Patent GB-875029-A (GB)
Title: Method and apparatus for producing pinch discharge
IPC: H05H1/12
Filed: 1959-05-07
Abstract: 875,029. Nuclear fusion reactors; discharge apparatus. UNITED STATES ATOMIC ENERGY COMMISSION. May 7, 1959 [June 16, 1958], No. 15665/59. Classes 39(1) and 39(4). Nuclear fusion apparatus comprises an electric gaseous pinch discharge tube provided with evacuation and gas supply means, means for supplying an initial axially symmetric stabilizing magnetic field, means for initiating and establishing the gaseous pinch discharge and for providing a plasma in which the initial stabilizing magnetic field is trapped and the plasma is compressed leaving a residual portion of the field in the plasma external to the main plasma column, and means programmed as a function of the compression for supplying a magnetic field to the tube to modify the boundary value of the external field. The apparatus shown in Fig. 2 comprises a tube 11 of quartz or the like closed at each end by electrodes 12, 13 between which the discharge is formed. A longitudinally split neutron conductor 22 is attached to the outside of electrode 12 and extends concentrically -with the tube 11 to a flange 23 which is spaced from a flange attached to electrode 13 of an insulator 24. A pipe 27 extends through electrode 12 to allow the apparatus to be evacuated and filled with deuterium or a deuterium/tritium mixture; a quartz tube 34 containing a pinch-up coil is sealed through electrode 12 by a bellows so that it may be moved about within the discharge space. A sparking plug type of trigger 28 allows the gas to be ionised before the main discharge. The tube 11 is surrounded by a solenoid 46 and by a solenoid 42 comprising a helical conductor embedded in a laminated resin. In operation a condenser is discharged through solenoid 46 which is subsequently shortcircuited to establish the stabilizing magnetic field. A pulse is applied to trigger electrode 28 and a condenser bank is discharged between electrodes 12 and 13. Solenoid 46 may be connected in parallel with the main discharge or may be connected to a separate condenser which is discharged through it. In a modified apparatus, Fig. 10 (not shown), solenoids 42 and 46 are omitted and the return conductor 22 is divided into insulated segments arranged along a helical path of shallow pitch. In another arrangement, Fig. 20, the discharge tube is a toroid constructed of two halves 202, 203 provided with flanges which are joined together. A metal foil or plating 212 covers the two halves to form a stabilizing shell, the foils being joined across one pair of flanges but not across the other. Insulated solenoidal windings 216, 217 are provided round the tube which is provided with conduits 234, 236 for filling the chamber with deuterium at 5-20 microns and with sparking plugs 232, 233. A single turn primary winding 218 comprises two halves 219, 221 having terminal flanges abutting across insulators 227, 228 and encases the upper, lower and outer sides of the discharge tube. Flanges 231 prevent collapse of the primary shell and laminated iron cores may be provided between the flanges. In operation a condenser bush is discharged through coils 217, 218 in series to establish the stabilizing magnetic field, and electrodes 232, 233 are energized to ionise the gas. Condensers are connected between both pairs of flanges of the primary winding to establish the pinch discharge, and the insulators 227, 228 are then short-circuited to allow the discharge to decay exponentially. Another condenser is then discharged in the reverse direction through coils 217, 218 to reduce or reverse the stabilizing magnetic field outside the plasma.