Breakdown Experiment under Low Pressurized Gaseous Condition Using a High Power Millimeter Wave Gyrotron Oscillator

Abstract

We present plasma breakdown experiment under different gaseous condition in pressurized vacuum chamber using high power source of millimeter wave oscillator, gyrotron. The generated output beam from a W-band gyrotron with tens of kW is reflected and focused by spherical mirror and teflon lens, respectively. When the focused beam approaches the threshold power density, breakdown phenomenon occurs inside of the vacuum chamber. We detect breakdown signal optically when the energy of the incident beam converts to visible light due to the interaction of beam and air gas particles. With amplitude and pulse length of incident gyrotron wave, we determine the characteristic time of breakdown. From this experiment, threshold power and characteristic time for breakdown events will be determined.