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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.

The characteristics of the plasma-filled diode when changing the current rise rate by 2 times were obtained. The rise rate was varied by changing the inductance of the secondary coil vacuum line of the linear transformer used as a pulsed power driver. The possibility of increasing the current amplitude by increasing its rise rate was demonstrated at fixed initial conditions. So, increase in the current rise rate by 2 times resulted in the rise of the current amplitude from 100 to 185 kA, transmitted charge from 6 to 10 mC while retaining the low-resistance phase duration of 100 ns. At the current amplitude rise by more than 1.5 times, the diode impedance rise rate in a high-resistance phase was retained at the level of 0.5 Ω/ns which allowed increasing the diode power by 1.6 times from 100 to 160 GW. The diode voltage remained at the level of approximately 1 MV due to the fast current drop in a high-resistance phase. Conservation of the resistance rise rate allows forecasting the growth of the diode voltage proportional to the current in case of increasing the current rise rate without reducing the inductance.