Production of atmospheric pressure high purity toroidal plasma

A new argon gas atmospheric pressure toroidal plasma source in a quartz discharge tube has been developed to obtain a highly pure and dense plasma. The initial plasma is obtained at a pressure of around 5 Torr in the discharge tube by the RF induced E field. By adding the argon gas vortex flow to insulate the plasma from the wall, a stable toroidal plasma is sustained up to 760 Torr at 7.8 kW RF power (2 MHz). The argon gas flow speed in the discharge tube is observed by the visualization method. The argon emission intensity distribution, excitation temperature and electron number density are measured by spectroscopic method. (author)