Gradual tuning of the current pulse width within 1–0.03 ns in gas-filled diodes of nanosecond electron accelerators

Abstract

The objective of the work is to study the beam current amplitude and pulse width at a voltage pulse rise time of -0.3 ns for interelectrode gaps of differing width in a diode pumped down to a pressure of about 0.01 Torr and filled with different gases (air, nitrogen, and helium). SLEP-150 generator with a tubular cathode was used. The conducted studies show that with subnanosecond voltage pulse rise times, it is possible to gradually vary the FWHM of the beam current pulse over a wide range. The FWHM and shape of the beam current pulse was varied by varying the pressure and gas kind in the diode. It is shown that in the vacuum diode mode, the beam current rise time decreases from 0.5 to 0.2 ns as the interelectrode gap is decreased from 12 to 2 mm. It is found that with a 3-mm interelectrode gap, increasing the air pressure in the diode of the SLEP-150 generator from 0.1 to 6 Torr decreases the FWHM of the current pulse from 1 to 0.18 ns, with the beam current amplitude greater than 400 A and the beam current rise time less delayed with respect to the voltage pulse rise time. The attained beam current density at a beam current pulse width of 0.18-1 and 0.1 ns is 500 and 100 A/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , respectively.