High-Current Vacuum-Arc Plasma Source for Producing Supersonic Plasma Flows in Magnetic Fields

Abstract

Supersonic plasma flows are used for surface modification of steels and alloys, simulation of plasma effects on the walls of fusion facilities, and laboratory research in astrophysical phenomena such as coronal loops on the Sun or planetary magnetospheres. The paper presents a high-current vacuum arc source which produces supersonic dense plasma flows of metal ions whose estimated velocities lie in the range of Mach numbers $\mathrm{M}=3-6$. The source is designed to study the interaction of dense pulsed plasma flows with strong magnetic fields of a few Tesla at electron cyclotron resonance. The source with its power supply allows one to widely vary the plasma density (1013–1015part/cm3), the arc current, and its pulse duration and to form arc current pulses of different shapes. In the experiments reported, we used two different shapes of arc current pulses: a quasi-rectangular pulse with an arc current of 0.2-3.5 kA and duration of $700\ \mu\mathrm{s}$ and a sine-wave pulse with an arc current of 1–25 kA and duration of about $120\ \mu\mathrm{s}$. The pulse repetition rate was up to 0.1 Hz. The pulsed energy of the source was up to 2.5 kJ. In the paper, we consider the design features and parameters of the plasma source, the results of measurements of the plasma flow parameters, and the effect of a strong magnetic field with different LC line configurations.