Soft X-ray emission in the (1.0-1.5 keV) window with nitrogen filling in a low energy plasma focus

A study of soft X-ray emission in the 1.0-1.5 keV energy range from a low energy (1.15 kJ) plasma focus has been conducted. X-rays are detected with the combination of Quantrad Si PIN-diodes masked with Al (50 mum), Mg (100 mum) and Ni (17.5 mum) filters and with a pinhole camera. The X-ray flux is found to be measurable within the pressure range of 0.1-1.0 mbar nitrogen. In the 1.0-1.3 keV and 1.0-1.5 keV windows, the X-ray yield in 4pi-geometry is 1.03 J and 14.0 J, respectively, at a filling pressure of 0.25 mbar and the corresponding efficiencies are 0.04% and 1.22%. The total X-ray emission in 4pi-geometry is 21.8 J, which corresponds to the system efficiency of about 1.9%. The X-ray emission is found dominantly as a result of the interaction of energetic electrons in the current sheath with the anode tip. Images recorded by the pinhole camera confirm the emission of X-rays from the tip of the anode.