Lempert Walter R, Kearney Sean P, Barnat Edward V
Department of Mechanical & Aerospace Engineering, The Ohio State University, Columbus, Ohio 43210, USA.
Appl Opt. 2011 Oct 10;50(29):5688-94. doi: 10.1364/AO.50.005688.
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.
我们展示了一项诊断研究的结果，该研究利用相干四波混频对空气或含氮等离子体中的电场进行原位测量。在标称压力为625托、温度为300K的空气中，利用氮气的振动相干反斯托克斯拉曼散射（CARS）检测静态电场。结果表明，在8.33 kV/cm时，红外信号与振动N₂ CARS信号的比值约为10⁻⁸，比假设三阶非线性极化率相等时预测的值小约50倍。研究还表明，典型共线几何测量的空间分辨率约为1厘米。最后，研究表明，要实现1 kV/cm量级的灵敏度，需要在高度饱和和斯塔克展宽的 regime 中进行相干拉曼泵浦。 （注：最后一句中的“regime”可能是特定领域术语，这里保留英文未翻译，因为不清楚其准确对应的中文术语，如果有更准确的术语可替换。）
