Knowledge Bank

Plasma diagnostics using laser spectrometers has been successful in measuring ion mobility(1), ion density distribution(2) and high electric field in the cathode region(3). We have attempted to measure the electric field in situ in the positive column of D.C. glow discharges by observing first order Stark splitting of CH3F Lamb dips using CO2-Microwave side band spectrometer. The strong R(4,3) transition gave clear Lamb-dip signals for the pressure range from 10 to 60 mTorr (approximately) in discharges and was used as the monitor. Varying discharge conditions and two air cooled discharge cells were used. No Stark splitting was observed even with discharge voltage of up to 24kV.