Spectroscopic study on a thermoelectron-enhanced microplasma jet

Abstract

An Ar thermoelectron-enhanced microplasma (TEMP) jet was characterized by spectroscopic study. The 1s5 lowest metastable densities at the core of the plasma and very close to the substrate, about 4 mm apart from the torch, were obtained successfully using laser absorption spectroscopy (LAS) and laser induced evanescent-mode fluorescence spectroscopy (LIEF). For TEMP generated with 450 MHz, 5 W and 60 Torr, these densities were estimated to be about 3 × 1012 cm−3 and about 1010 cm−3, by the LAS and LIEF methods, respectively. Moreover, gaseous temperature was also estimated as about 700 K by the LAS method. Depopulation of the 1s5 metastable atoms might be caused primarily by gaseous diffusion between the torch and the substrate. Finally, we report a device with a TEMP generator at the top of a flexible fibre called the 'plasma fibre', which allows plasma processing in any location, as with laser processing using an optical fibre.