Diagnosis of high-pressure microwave-induced hydrogen plasma using atomic emission spectroscopy

The H Balmer emission lines have been measured on a high-pressure microwave plasma apparatus with pure hydrogen at 2.45 GHz. The broadening caused by Stark effect was obtained by separating (deconvolution) the Doppler broadening and instrumental broadening, which were supposed to be Gaussian profiles, from the total broadened profile. The electron density and the electric field were simultaneously obtained by the derived Stark broadening of spectral lines. The results indicate that both the electron density and the electric field strength increase with the increase of microwave power, and they increase initially and then decrease with the increase of the pressure. Their peaks are respectively 3.55×12 cm-3 and 4.01 kV/cm at the gas pressure of 25 kPa when the microwa