Investigation of high-voltage water-switch breakdown using laser probing diagnostics

Summary form only given. First results on advanced laser-probing investigation of high-voltage water-switch breakdown are presented. An experiment was done on small-scale installation which imitates the rise-time and electric field conditions for ZR and RITS water switches. Experiments were done for self-breakdown and laser-triggering regimes of operation. The electrical diagnostics include upstream current measurement using Rogowski monitor and voltage using capacitive divider. Laser-probing diagnostics include two-wavelength interferograms, shadowgrams, absorption, Schlieren and Faraday rotation techniques. This set of laser diagnostics allows determination of the size of the streamer, electron density, temperature, magnetic field and other important parameters of breakdown processes. The streak-image of cathode-anode gap in self-emission light and using long-pulse laser backlighter gives the structure and propagation speed for streamer. Optical diagnostics are time-correlated with current and voltage waveforms. The experimental results are compared with computer simulations.