Negative-polarity nanosecond-pulsed cryogenic plasma in liquid nitrogen

TL;DR

This study investigates the optical emission spectrum and behavior of negative nanosecond-pulsed cryogenic plasma in liquid nitrogen, revealing insights into discharge modes, pressure, and temperature conditions.

Contribution

It provides the first detailed spectroscopic analysis of negative cryogenic plasma discharges in liquid nitrogen, highlighting similarities with positive streamers.

Findings

Discharge mode switches at around 5 MV/cm electric field.

Negative streamers reach pressures of tens of atmospheres.

Temperatures of streamers are approximately 140-150 K.

Abstract

In this work we report the results of imaging and spectroscopic measurements of optical emission spectrum of negative nanosecond-pulsed cryogenic discharge in liquid nitrogen. With the application of lower electric fields, the discharge first ignites as a 'faint glow' around the high voltage needle electrode, while when the applied electric field reaches transition value of around 5 MV cm-1, the discharge mode switches to negative in-liquid streamer. Optical emission spectrum of the discharge is populated by the molecular nitrogen emission bands, and their analysis shows that the pressures and temperatures of the negative streamers in liquid nitrogen are at least of few tens of atmospheres and around 140-150 K. The results of the study demonstrate similarity of positive and negative streamers in the cryogenic in-liquid plasma conditions.