The laser triggering of high-voltage switches

Abstract

The laser-triggered switching (LTS) of high-voltage spark gaps is considered. The basic theory is presented which predicts dependencies of the delay to breakdown and switching jitter on such variables as fill gas mixture and pressure, gap spacing, polarity, and geometry. It is shown that electrical arcs of several metres length can be directed by laser action. A complete set of experiments is reported which adequately support the proposed theory. The performance of LTS is considered and results are reported on multiple gap triggering, multiple channel triggering, triggering of voltages in excess of 3 mV, repetitive switching at rates up to 50 pps with subnanosecond jitter, as well as various geometries, pulse forming demonstrations, and output voltage selection on a Marx generator.

Gas-filled laser-triggered spark gap

“…The infrared Nd:YAG lasers with output energy of a few hundreds mJ are widely used for laser-triggered switching [3]. This can be explained by their possibility to exceed easily the intensities necessary for tunnel-ionization of atoms and molecules.…”

Towards a fully kinetic 3D electromagnetic particle-in-cell model of streamer formation and dynamics in high-pressure electronegative gases

“…Accurate modeling of these physical processes is essential for a number of applications, including highcurrent, laser-triggered gas switches. [8][9][10][11] With this goal in mind, we present a new 3D implicit particle-in-cell (PIC) simulation model of gas breakdown leading to streamer formation in electronegative gases. Within the framework of the Lsp electromagnetic (EM) PIC code, 12,13 a Monte Carlo treatment for all particle interactions is used, which includes discrete photon generation, transport, and absorption for ultra-violet (UV) and soft x-ray radiation.…”

Four-channel laser-triggered spark gap

“…The fastest way to switch a triggered spark gap is with laser pulse, which creates plasma between electrodes with extreme rapidity. Laser triggering of these high voltage switches offers many advantages over electrical triggering [2]:…”