Plasma focus discharges have historically produced copious neutrons or x-rays at moderate energies and with high efficiency. The optimized output scaling for both neutrons and xrays has followed an approximate power law in current (with the power between 3 and 4) up to currents of order one megampere and stored capacitor energy of order one megajoule. However, this favorable scaling has not successfully been extended beyond these levels. Conventional plasma foci are initiated by a highcurrent, low-inductance discharge through a static gas prefill wluch lifts off an insulator. One serious problem for high-energy operation is restrike across the initiation insulator, caused by a combination of ultrtaviolet photons from the plasma current sheath and rather large inductive voltages during the subsequent run-down and implosion phases. The result is current shunting and loss of drive pressure for the pinch.An alternative scheme involves a plasma flow switch (PFS), in which a conducting plasma armature convects toroidal magnetic flux to a downstream load. This type of switch is ideally suited to low-voltage, rising-current energy sources such as capacitor banks or magnetocumulative generators. A variation of this approach the use of a magnetized plasma armature, which has significant stability advantages over unmagnetized plasmas.We describe a novel dense plasma focus experiment at the Shiva Star facility (operated at 1 MJ -2 MJ capacitor bank energy), which uses a compact toroid (CT) magnetized plasma flow switch to initiate the focus implosion downstream from a shielded vacuum insulator.The CT armature stably and reproducibly translates up to 3 MA from the vacuum feed region through coaxial electrodes to a puffed-gas central load. The inertia of the 1 mg CT and the work that must be done in compressing the intemal magnetic fields during the translation provide a delay in current delivery to the pinch of 5 ~ 10 ps, which matches the bank quarter cycle time relatively well. Effectiveness of the current delivery was monitored by primarily by inductive probes in the PFS region, fast photography of the focus, and x-ray and neutron measurements of the pinch. No evidence of current loss was observed.When DPF is fired with the vessel filled by a mixture of HZ ( C, N, 0 ) and LZ ( D2, 3He ) elements, a strong yield Y(HZ+LZ) of HZ+LZ reactions is observed ['].These reactions differ strongly i n energy of the involved ions: E . > 1 MeV for HZ+LZ and E.iO 3MeV for LZ+LZ. &Ten though, HZ+LZ and LZ+k? ieactions do not necessary occur in the same space location ['], the corresponding yields are correlated as Y (HZ+LZ ) -Y2 (LZ+LZ) c2 . To understand this phenomenon the time structure of D(d,n)-neutrons and hard X-ray emission have been correlated with the time integrated Y(HZ+LZ). The plasma focus (7kJ; 17kV) was fired with t h e vessel filled by D2 + O2 mixture. Some of the recorded data are: [ a ] dPn/dtvariation of the neutron signal (NE102 at 15cm from source), [b] d(P +P )/dt -X-ray (E,,SOkeV) and time-or-fyight distorted neutr...
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