Parasitic X-ray emission from high voltage plasma focus device

Spectroscopic measurements of the soft X-ray emission of the high voltage plasma focus devices SPEED 2, operating in different mixtures of D2 and Ne or Ar, evidenced, in certain conditions, strong impurities' emission related to the anode material. Both characteristic Cu K lines and thermal lines emitted by the Ne-, F-, and O-like Cu ions were observed. The source of this radiation was identified to be a small region in the the vicinity of the anode surface center. This emission could be related to the existence of energetic electron beam bombarding the anode surface. Some effects of this 'parasitic' emission on the ionized gas spectrum and on X-ray measurements are discussed. (authors)