Experimental Observation of Hot Spots in a Filippov-Type Plasma Focus Device

In this paper we have presented the experimental results of hot spots observation in different working conditions in Filippov-type Plasma Focus Device “Dena” (90 kJ, 25 kV), analyzing of these results have shown that the working conditions have great influence on hot spots formation. In using the pure gases like D₂, Ar, Kr and Ne the formation of hot spots has been seen rarely, and it can be related to impurities like vapoured metal from the anode surface, also in using the light impurities hot spots were not formed, and only for the heavy impurities like Kr the formation of hot spots have been observed. The discharge voltage also plays an important role in hot spots formation, for voltages less than 16 kV, hot spots have not been observed. Also, using the conic insert anode leads to more and distinct hot spots than the case of flat one. The best results of hot spot observation in these experiments have been achieved by using a conic insert anode and D₂ + 1% Kr as working gas.