USE OF FLUORESCENCE SPECTROSCOPY OF CS FOR MEASUREMENTS OF ELECTRIC-FIELDS IN A DISCHARGE PLASMA

It is demonstrated that the use of LIF spectroscopy of CS molecules pr ovides sensitive measurements of plasma electric fields with high spat ial resolution. The experiment was performed in a helium glow discharg e which was produced in a discharge vessel applying a voltage to two g old-plated electrodes (60 mm in diameter, 40 mm spacing). The CS molec ule admixture was generated by a rf discharge in a CS2 gas flow system outside the discharge vessel. The plasma parameters in the negative g low discharge were obtained by probe measurements. The electron densit y was about 10(10) cm(-3) and the electron temperature was 0.2 eV on t he discharge axis for U-discharge = 1200 V, I-cathode = 1 mA and heliu m gas pressure p(0) = 0.5 mbar. The measured electric field strength w as in the range of 100 V cm(-1) less than or equal to F less than or e qual to 1200 V cm(-1) and its spatial distribution in the cathode fall region is in good agreement with cathode fall theory.