GB1018504A - An arrangement for the production of neutron pulses - Google Patents

Abstract

1,018,504. Heavy ion beam tubes. INSTITUT FUR PLASMAPHYSIK G.m.b.H. Oct. 17, 1962 [Oct. 25, 1961], No. 39290/62. Heading H1D. In an arrangement for the production of high intensity neutron pulses a glass envelope 1 has at one end a cup-shaped cathode 2, carrying a target 5, and at the other end an anode 4 which is narrowed to a diaphragm 5. Inside the anode is a reflector rod 6, connected to the anode and having a concave head 7. The anode is surrounded by a glass sheath 8 having a diaphragm between the anode and cathode which prevents unwanted discharges. occurring on the outside of the anode and acts as a lens electrode being negatively charged by secondary electrons. On the occurrence of a disruptive discharge, a tubular plasma is formed in the aperture of the anode diaphragm, covering a sufficiently large area of the target 3, wherein the electrons impinging on the anode and the reflector rod are diffused back and subjected to multiple reflection to increase the probability of ionization, further, the hollow anode and reflector form a high frequency tank circuit which is excited by the voltage variation between anode and cathode and by the interaction of injected electrons. The high frequency alternating field developed in the vicinity of the aperature lengthens the electron path and accelerates slow electrons. To increase the probability of ionization the reflector rod can be made of a permanent-magnet material with a high Curie-point. The neutrons formed are withdrawn from the hollow-anode and accelerated to the target. The metal parts are of hollow construction. The ignition pressure for a deuterium filling is 7 x 10<SP>-2</SP> Torr at an operating voltage of 150 kv. An annular electrode 13, electrically connected to the cathode, assists in preventing surface discharges between the fusion points of the anode and cathode. The power-supply comprises a capacitor 9, consisting of a plurality of lengths of high voltage cable in parallel discharging from an electrode 10 to a terminal cap 11 connected to the anode. In a modification, Fig. 3, not shown, the cathode is everted and the glass sheath is not used.