Diagnostic of rf discharge plasma by Thomson scattering with gated intensified charge coupled device detectors

A Thomson scattering diagnostic, using an intensified gated charged coupled device detector and a high-repetition rate yttrium aluminum garnet laser, was utilized to measure electron parameters in a radio-frequency discharge. Both inductively and capacitively coupled plasmas in argon and argon-oxyge n mixtures were studied, with electron densities as low as similar to 5x10( 9) cm(-3). Different modes of detection (direct accumulation and photon cou nting) have been compared. The photon counting technique has been used to p rovide better accuracy at low light level (i.e., low electron densities). T he results are compared with Langmuir probe measurements performed under th e same plasma conditions, and good agreement is found between the two diagn ostics. (C) 2000 American Vacuum Society. [S0734-2101 (00)03804-5].