COMPARATIVE-STUDY OF ION, X-RAY AND NEUTRON EMISSION IN A LOW-ENERGY PLASMA-FOCUS

In a low energy (2.3 kJ) Mather-type deuterium plasma focus, neutron a nd x-ray emission is investigated by time integrated and time resolved detectors. CR-39 nuclear track ion detectors are employed for measuri ng charged particle angular distribution. Correlation of charged parti cles with neutron and x-ray emission is also investigated. The neutron emission profile is found to be composed of two pulses, the intensity and anisotropy of which vary with the filling pressure. The charged p article flux is maximum with high fluence anisotropy for the pressure range 2.5-3.0 mbar which is also the optimum pressure for high neutron emission with low fluence anisotropy (similar to 1.5), The high neutr on emission with low fluence anisotropy is attributed to the presence of trapped deuterons in an anomalous magnetic field. The relevant pres sure range generates favourable conditions for plasma density and pinc h filament diameter. X-ray emission is generally high at low pressure. For the pressure range of 2.5-4.0 mbar, the axial neutron detector re gisters a hard x-ray pulse, which may escape through a half inch thick Cu flange. These results suggest that at low pressures, the collapsin g current sheath interacts with the anode end and causes intense low e nergy (110 keV) x-ray emission, but the neutron emission remains low. X-rays are dominantly Cu K alpha. In the narrow pressure regime 2.5-3. 0 mbar, the current sheath forms a pinch filament leading to high neut ron yield with low fluence anisotropy.