Two Phases of Neutron Production in the Poseidon Plasma Focus.

摘要

Various measurements performed in the 280 kJ, 60 kV operational mode of the Poseidon plasma focus confirm that at high pinch currents (approx.= 1 MA) there exist two phases of suprathermal neutron production. In the pinch phase, the neutron emission from a macroscopically smooth, relatively quiet thermal (Tsub(i) approx.= 1 k to 0.4 keV) plasma column is very likely caused by accelerated deuterons ( <= 400 keV) trapped for up to 100 ns in the pinch by gyro-motion and relaxation. MHD calculations suggest that the acceleration may be due to an MHD-instability induced reconfiguration process, leading to current filamentation and high Bsub(z)-fields. In soft X-ray pictures filaments, particularly a central filament, were observed. Indications for Bsub(z)-fields were deduced from the directions of the reaction proton trajectories. The rather irreproducible, strong neutron production in the second phase is associated with m = 0 pinch break-ups and with fast deuterons accelerated mainly in axial direction. (ERA citation 10:032897)