Investigation of electron and ion beams in mega-ampere fiber pinch plasmas

The latter stages of fiber Z-pinch discharges at current levels up to 1.4 MA with a rise time of 150 ns have been investigated on the MAGPIE generator. Carbon fibers with a diameter of 33 /spl mu/m and deuterated polyethylene (CD/sub 2/) fibers with diameters between 50 and 200 /spl mu/m were used as loads. The detection of hard X-rays and neutrons provide evidence for MeV electrons and ions. The hard X-rays occur around 120-200 ns into the discharge and typically last for between 20 and 100 ns. Beam target neutrons have also been detected at this time with neutron energies of up to 5.2 MeV. Optical and X-ray diagnostics indicate that the dynamic hot spot phase of the pinch is over by this time and that no rapid pinching or expansion of dense plasma is occurring. The pinch is seen to be composed of high density regions along the axis interspersed by tenuous regions where the density is at least two orders of magnitude lower. A conceptual model which is consistent with the experimental data is proposed to explain the energy and duration of the X-ray and neutron pulses.