Characteristics of a vacuum spark triggered by the transient hollow cathode discharge electron beam

The discharge characteristics of a vacuum spark triggered by the transient hollow cathode discharge (THCD) electron beam is investigated over a wide variety of discharge conditions. Two systems of the vacuum spark device have been considered-the first system powered by eight 2700-pF doorknob capacitors charged to a voltage of 40 kV (input energy of 17.6 J); while the second system employs a single 1.85-μF Maxwell capacitor discharged at a voltage of 20 kV (input energy of 370 J). The operating pressure of these systems has been varied over the range of 10 ^-2 to 10^-5 mbar in order to examine the effect of the operating pressure on the plasma formation of the vacuum spark discharge. The effectiveness of plasma heating has been found to be significantly enhanced in the two vacuum spark systems studied here. In particular, the plasma of the 17.6 J system has been observed to be heated to a condition hot enough to emit in the X-ray region when the operating pressure is reduced from 10^-2 to 10^-5 mbar. Similarly, in the case of the 370 J system, hot spot formation is also observed to occur only at a low operating pressure of 10^-4 mbar