Gap length dependence of two-dimensional electron and copper vapour density distribution over vacuum plasma

Abstract

Shack-Hartmann type laser wavefront sensors were used for simultaneous visualisation of two-dimensional electron and copper vapour density distributions over vacuum plasmas in a breakdown phase and sustainable arc phase. Our experimental results for a 3-mm gap between Cu electrodes showed that the electrons in the vacuum breakdown stage were mainly supplied from the ionisation process of the copper vapour evaporating from the anode. In addition, the electron and copper vapour densities in an intense arc mode for the 3-mm gap were comparable to those for the 1.2-mm gap in our previous experiments. The validity of the observation results was verified by simultaneously recorded voltage and current waveforms demonstrating an inversely proportional decrease in arc column conductance with increasing gap length. K: Voltage distributions; Plasma diagnostics -interferometry, spectroscopy and imaging 1Corresponding author.

Spatial-filter-installed Shack–Hartmann sensor for two-dimensional electron density visualization of SF6 arc discharge under strong turbulent flow

“…On the other hand, these sensors can be utilised for various kinds of arc-quenching media without a theoretical assumption such as local thermodynamic equilibrium [13][14][15][16][17], because they measure a refractive index distribution induced by the electrons in arcs, which is an universal property of discharge plasmas. Therefore, this method is also applicable to feasibility study of the recently proposed SF 6 alternative gases, e.g.…”

Two-dimensional electron density characterisation of arc interruption phenomenon in current-zero phase

“…The Shack-Hartmann sensors have also been used for vacuum arcs [31][32][33], whose electrons are mainly supplied by the thermo-field emission from the cathodes and the ionisation of the metal vapour generated by the erosion of the electrode materials. On the other hand, electrons in gas arcs are mainly supplied by the thermo-field emission and the ionisation of the background gas, e.g.…”

Influence of CuCr electrode composition on 2D electron and metal vapor density distribution over vacuum arc

“…Recently, we have been utilizing a ShackHartmann-type laser wavefront system for simultaneous single-shot visualization of the electron and metal vapor densities over the vacuum arc plasma [17][18][19]. Although the usual sensing methods provide the electron or metal vapor density at only one position from a single-shot recording, the ShackHartmann system has the advantage of single-shot visualization.…”