Sensitive, Nonintrusive,In-SituMeasurement of Temporally and Spatially Resolved Plasma Electric Fields

A new technique is reported for in-situ, nonintrusive, and sensitive measurement of plasma electric fields with high spatial resolution (≲${10}^{-4\mathrm{}}$ ${\mathrm{cm}}^3$). Fields as small as 40 V/cm are measured by spectral resolution of laser-induced fluorescence from Stark-mixed parity levels. The technique is demonstrated by excitation of the $A{}_{}{}^1{}_{}{}^{}\Pi -X{}_{}{}^1{}_{}{}^{}\Sigma _{}^{+}{}_{}{}^{}$ band system of BCl, produced in an rf discharge through B${\mathrm{Cl}}_3$. The absolute measurement of sheath fields, which has been elusive, is now possible.