Study of Soft X-ray Emission from Sahand as Filippov Type Plasma Focus Using Different Cathode Type

To the best knowledge of the authors, so far, the detailed experimental effect of the cathode type on the X-ray yield in the Filippov type plasma focus devices has not been documented in literatures. Our results show that changing the cathode, affects significantly on the efficiency of X-ray production. Therefore, the main aim of the current study is to provide experimental data showing that the open-squirrel cage cathode is the best choice regarding the X-ray yield for typical Filippov type plasma focus at least among a few different types of cathodes that widely have been used. The effect of three different cathode types (i.e., open-squirrel cage, close-squirrel cage, and cylindrical) on the pinch current and neon soft X-ray yield is investigated experimentally in a plasma focus device. The results confirm that the pinch current depends on the cathode type and in open-squirrel cage cathode it is higher than two other cases. The results also confirm that a large fraction of the maximum current is transferred to the plasma column. Experimental results also show that the time difference between pinch and maximum currents with open-squirrel cage cathode is less than two other cathodes. Using two channel diode X-ray spectrometer, the effect of cathode type on the neon soft X-ray emission at constant pressure (0.5 Torr) and different voltages (10-15 kV) is investigated. In the open-squirrel cage cathode with increasing voltage, the average neon soft X-ray yield increases approximately linearly whereas for close-squirrel cage and cylindrical cathodes the neon soft X-ray yield has a maximum (at 12 kV for cylindrical and 13 kV for squirrel cage cathode). The maximum neon soft X-ray yield for the open-squirrel cage cathode is 21.9 +/- 3.4 J at 15 kV and for the cylindrical cathode 16.4 +/- 1.2 J at 12 kV and for close-squirrel cage cathode 15.9 +/- 3.4 J at 13 kV.