Measurement of plasma stream velocity in a pulsed plasma accelerator

Abstract

The measurement of plasma stream velocity in a coaxial pulsed plasma accelerator using two pairs of double plate probe (DPP) is reported in this article. The device produces a quasisteady type high velocity and high energy plasma stream for a duration of a few hundreds of microseconds. A simple arrangement of DPP with capacitor based biasing circuits was developed in-house which detected two different instances of plasma stream reaching the probe plates. This time interval gave the measure of plasma stream velocity using the known distance of separation between the probes. A spectroscopic study of the stream velocity was also performed to validate the findings of DPP. In this experiment, nitrogen and argon gases were considered as the operating medium. The velocities of Argon and Nitrogen were found to be (25 ± 1.5) km/s and (28.5 ± 0.5) km/s, respectively. The energy density of the plasma stream is calculated from the measured velocity, and it is found to be (0.8 ± 0.05) MJ/m2 for argon plasma and (0.3 ± 0.02) MJ/m2 for nitrogen plasma. The value of energy density is significant for studying fusion relevant plasma matter interaction.