Low-resistance high-current discharge initiation in a vacuum diode

Summary form only given. Preliminary creation of ion flow in a vacuum diode before applying the voltage pulse allows removing the beam current limitation by own space charge, reducing the diode impedance, and increasing the beam power. The sources based on the surface dielectric breakdown are most widely used to create a plasma flow. Plasma extends as a result of hydrodynamic expansion with a velocity of ~10⁶ cm/s determined by the plasma temperature (units of eV). Besides this, the ions with the velocities exceeding the thermal velocity are recorded. It is evident that this flow can be used for ion compensation of the electron beam charge in high-current relativistic diodes. This paper presents the results of oscillographic study of the ion flow propagation from a capillary plasma gun in combination with single-frame photography of plasma glow with a resolution up to 3 ns. Ignition of a high-current low-resistance discharge with the current of 100 kA in the absence of complete filling of the diode gap with plasma is demonstrated. The situation in which plasma fills only a part of the diode gap prior to ignition of high-current discharge is favorable for the realization of the current cutoff with a high rate.