The remaining challenges, confronting high-power microwave sources and pulsed power technology, stimulate the development of robust relativistic electron beam sources. This paper presents a carbon-fiber-aluminum cathode with high-density uniform emitters, which was tested in a single pulsed power generator (~450 kV, ~350 ns, ~50 Ω) and a repetitive one (350 kV, <10 ns, 150 Ω, and 100 Hz). The distribution and development of the cathode plasma was observed by time-and-space resolved diagnostics, and the uniformity of electron beam density was checked by taking x-ray images. A quasi-stationary behavior of the cathode plasma expansion was observed. It was found that the uniformity of the extracted electron beam is satisfactory in spite of individual plasma jets on the cathode surface. Under repetitively pulsed operation, this cathode exhibited a good shot-to-shot reproducibility even in poor vacuum. This new class of plasma cathodes offers a promising prospect of developing relativistic electron beam sources.

The test on an X-pinch device powered by a pulsed power generator (PPG-I) was carried out step by step. In the first step, a brass rod of 6 mm in diameter was used as a load to replace the X-pinch load. The results of the first step shows that all the current, about 200 kA in amplitude, output from PPG-I flows through the load and no breakdown or flashover in vacuum of the load section happens. The waveform of the current from PPG-I measured with a wall resistor coincides exactly with that of the load current measured with a Rogowski coil, which indicates that the calibrations of the wall resistor and Rogowski coil are correct. In the second step, an X-pinch load made of two molybdenum wires of 40 µm in diameter was used. It was found that the distance between the cathode and anode affects considerably the operation of the device. While breakdown in vacuum happens for the distance equal to 30 mm, it works very well for the distance equal to 16 mm. The reason for this phenomenon was given.

A pulsed power generator by inductive voltage adder, versatile inductive voltage adder (VIVA-I), which features a high average potential gradient (2.5 MV/m), was designed and is currently in operation,. It was designed to produce an output pulse of 4 MV/60 ns by adding 2 MV pulses in two-stages of induction cells, where amorphous cores are installed. As a pulse forming line, we used a Blumlein line with the switching reversed, where cores are automatically biased due to the presence of prepulse. Good reproducibility was obtained even in the absence of the reset pulse. Within ∼40% of full charge voltage, pulsed power characteristics of Marx generator, pulse forming line (PFL), transmission line (TL), and induction cells were tested for three types of loads; open-circuit, dummy load of liquid (CuSO4) resistor, and electron beam diode. In the open-circuit test, ∼2.0 MV of output voltage was obtained with good reproducibility. Dependences of output voltage on diode impedances were evaluated by using various dummy loads, and the results were found as expected. An electron-beam diode was operated successfully, and ∼18 kA of beam current was obtained at the diode voltage of ∼1 MV.