Ignition of Self-Sustained <i>Е</i>×<i>В</i> Discharge; Ion Contribution to Understanding the Process

Abstract

We determined critical values for the ignition voltage and magnetic induction for a self-sustained plasma discharge in crossed electric and magnetic fields, both at inert gases and in their mixtures. As parameters that enabled to visualize igniting an E×B discharge, we used the ion current and the induction current derivative, and provided the temporal characteristics for the process. We found a double structure of the ion current (discharge current) during the ignition. The working media initial state for the discharge current first jump is a neutral gas, whereas the working media initial state for the second jump is plasma. A peak of ions originated within the near-cathode area is detected on the energy distributions of the ions obtained during the ignition. Also detected is a wide ion energy spectrum related to the discharge gap. We show a various discharge ignition character for Penning pairs, when the gas changes its role (main or admixture) in the mixture. The character is determined by features of forming the electric potential distribution in the near-cathode layer.