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Description:
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The phenomenology of breakdown in gases and liquids , and surface flashover at atmospheric pressures are investigated with high -speed electrical and optical diagnostics . The experiments utilize a 50Q coaxial transmission line system with an axial discharge and a load line to simulate a matched terminating impedance . DC breakdown , and in part pulsed breakdown , are characterized for argon gas , subcooled liquid nitrogen , biodegradable oil and vacuum . The discharge current and voltage are measured via transmission line current sensors and capacitive voltage dividers , which have a working range of 0 .1 mA to IkA with temporal resolutions of 300 ps . Light emission is measured by photomultiplier tubes (800 ps risetime ) and high speed photography . Some results indicate the presence of prebreakdown events preceding the main self -breakdown . These events occur microseconds before the main breakdown as nanosecond current and luminosity spikes . |