STUDY OF ION MASS EFFECTS ON LONG CONDUCTION TIME PLASMA OPENING SWITCHES USING RESONANT DIAGNOSTIC TECHNIQUES

PLASMA EROSION OPENING SWITCHES (PEOS) ARE FINDING MANY APPLICATIONS IN PULSE POWER MULTIPLICATION AND THE SWITCHING OF INDUCTIVE STORAGE DEVICES FOR PULSED POWER APPLICATIONS. SUCH A SWITCH OPERATES BY USING AN EXTERNAL PLASMA SOURCE TO SHORT A GAP WHICH CONDUCTS CURRENT FROM A LOW VOLTAGE CAPACITIVE SOURCE FOR 100 NANOSECOND TIME SCALES. AT A CRITICAL CURRENT DENSITY THE PLASMA ERODES AND THE SWITCH OPENS ON A 10 NANOSECOND TIME SCALE TRANSFERRING A MULTIPLIED VOLTAGE TO THE LOAD. THE GAP PLASMA CONDUCTS IN A DIFFUSE MANNER THROUGHOUT THE OPERATION OF THE PEOS, A PHENOMENA WHICH CAN BE ACHIEVED IN SIMULATIONS ONLY BY INVOKING AN ANOMALOUS RESISTIVITY. A LIKELY SOURCE FOR THIS RESISTIVITY IS STREAMING PLASMA INSTABILITIES WHICH ARE MANIFESTED BY THE GROWTH OF ION ACOUSTIC WAVES. RESONANT-RAYLEIGH SCATTERING IS PROPOSED AS A METHOD TO DIRECTLY VERIFY THE EXISTENCE OF THESE INSTABILITIES AND TO STUDY THEIR PROPERTIES IN THE PEOS PLASMA. AT A WAVELENGTH NEAR AN ATOMIC TRANSITION THE RAYLEIGH LIGHT SCATTERING CROSS SECTION IS ENHANCED BY UP TO TEN ORDERS TO MAGNITUDE. WITH TYPICAL PULSED DYE LASER POWERS, THIS ALLOWS ONE TO DETECT ATOMIC OR IONIC SPECIES WITH DENSITIES AS LOW AS 10(10)CM(-3) WELL WITHIN THE RANGE OF PEOS PLASMAS.