Effective energy coupling for 200-Mhz pulsed radiofrequency spectroscopic discharges

The introduction of various new radiofrequency electrical discharges has placed increased emphasis on circuit design which provides optimal energy transfer between a generator and its corresponding spectroscopic “load”. This technology is well developed for high-frequency (ca. 27 MHz) inductively-coupled plasma discharges and for cavity discharges which operate in the microwave region (e.g., 2450 MHz). The 200-MHz very high frequency (VHF) region has received less attention. New circuitry is described which allows effective transfer of high power (5-kW), pulsed (2.5-μs), VHF (200-MHz) energy into a plasma suitable for analytical purposes. A triple-stub tuner is used in this circuitry. Comparison with other approaches and applicability to a variety of discharge systems are discussed.