Publications

Preliminary schlieren and optical emission diagnostics of a high-voltage laser triggered switch

Rose, Charles; Yalin, Azer P.; Simpson, Sean S.; Patel, Sonal P.

We present the setup and preliminary diagnostic measurements of an optically accessible high-voltage laser trigger switch (HV-LTS) operating with zero air and millimeter gap lengths. The switch is utilized as a test bed to collect electrical and optical measurements to inform recently discovered gaps in the Tom Martin switch model. We present the basic theory of this model including key assumptions on the radial plasma channel growth and constant electrical conductivity. Characteristic electrical measurements of the switch are presented including: self-break curve, minimum laser energy to trigger with ~100% reliability for various set voltages, and equivalent circuit resistance and inductance. Schlieren images are presented of the temporal blast wave associated with laser triggering, as well as switch closure plasma. Radial plasma growth is measured and found to agree with the Martin model assumptions, albeit with variability yielding a potential error in calculated resistance of ~15%. Optical emission spectra of switch closure are also recorded and show the spectra to be dominated by continuum at early times with emission lines becoming visible at ~200 ns after a 25 kV shot and ~500 ns after a 100 kV shot. This data, to the best of the author’s knowledge, represents the first publication of HV-LTS emission spectra.