Towards using the femtosecond laser E-Field measurement (FLEM) method for plasma discharges

To whom correspondence should be addressed; E-mail: [email protected]. Recently, a novel measurement method using a femtosecond laser has been under development for electric field measurements with the goal to measure electric fields in pulsed nanosecond discharges. Initial efforts have been taken for measurements in plasmas, and various experimental difficulties have been encountered. The key concerns are reduction of background EMI noise due to rapidly varying electric fields, shot-to-shot jitter of the laser pulse arrival with respect to the high voltage pulses, and emission due to plasma formation. An outline of how each of these problems has been overcome is presented, as well as initial measurements with the nanosecond pulsed high voltage unit. Calibrations have been completed at pressures as low as 25 Torr, and a temporal resolution of 250 picoseconds have been demonstrated.