Diagnostic study of four-wave-mixing-based electric-field measurements in high-pressure nitrogen plasmas

Walter R Lempert; Sean P Kearney; Edward V Barnat

doi:10.1364/AO.50.005688

Diagnostic study of four-wave-mixing-based electric-field measurements in high-pressure nitrogen plasmas

Appl Opt. 2011 Oct 10;50(29):5688-94. doi: 10.1364/AO.50.005688.

Authors

Walter R Lempert¹, Sean P Kearney, Edward V Barnat

Affiliation

¹ Department of Mechanical & Aerospace Engineering, The Ohio State University, Columbus, Ohio 43210, USA. Lempert.1@osu.edu

PMID: 22015362
DOI: 10.1364/AO.50.005688

Abstract

We present the results of a diagnostic study of the use of coherent four wave mixing for in situ measurement of an electric field in air or in nitrogen-containing plasmas. Static electric fields in air at a nominal pressure of 625 Torr and temperature of 300 K are detected using vibrational CARS of nitrogen. It is shown that the ratio of the infrared signal to the vibrational N(2) CARS signal is equal to approximately 10(-8) at 8.33 kV/cm, a factor of approximately 50 less than that predicted assuming equal third-order nonlinear susceptibilities. It is also shown that the spatial resolution of a typical collinear geometry measurement is approximately 1 cm. Finally, it is shown that achieving sensitivities of the order of 1 kV/cm requires that the coherent Raman pumping be performed in the highly saturated and Stark broadened regime.