Spectral investigations of micropinches in a plasma focus

Soft x-ray (SXR) spectroscopic structure has been investigated in a 3 kJ plasma focus device—NIE-SSC-PFF. The focused plasma is generated by an electrical discharge in neon gas between electrodes in a Mather-type plasma focus configuration. A crystal spectrograph capable of providing spatially resolved spectrum in the pinching column direction was developed and used to study the output of the pinched plasma region. For neon plasma focus the emission is found to be mainly in the wavelength range from 8 to 14 Å, with the helium alpha line at 13.447 Å and the hydrogenlike alpha line at 12.132 Å being the most intense features. Bright ‘micropinches’ or ‘hot spots’ within the plasma column were observed. The electron temperature in the ‘spots’ was estimated to be $∼300 eV.$ For lower pressure these ‘hot spots’ assumed a longish shape. In the case of higher pressure, point-like spots were more frequently observed.