First spectroscopic study of HFRC plasma

An advanced spectral diagnostic system was developed to measure the electron temperature ( T e ), electron density ( N e ), and ion temperature ( T i ) of the Huazhong University of Science and Technology field-reversed configuration plasma. The system consists of an optic fiber spectrometer with a wide spectral band and a 670 mm focal length high throughout Czerny–Turner monochromator equipped with both a 3600 g mm −1 grating and a 2400 g mm −1 grating to measure the line spectrum. Accompanying these components is an electron-multiplying charge-coupled device camera to capture spectral data. The relative intensity of the optical fiber spectrometer was calibrated using a standard luminance source, and the wavelength calibration of the spectrometer was accomplished using a Hg/Ar lamp. This diagnostic setup was configured to measure electron density based on the Stark effect of H γ ( n = 5 → n = 2; 434.04 nm). Doppler broadening of an O III (2s 2 2p( 2 P 0 )3p → 2s 2 2p( 2 P 0 )3s; 375.988 nm) emission line was measured and analyzed to obtain the ion temperature, and electron temperatures were estimated from the relative strength of H β ( n = 4 → n = 2; 486.14 nm) (D β ) and H γ (D γ ) spectral lines when the electron density was obtained from Stark effect measurements. The initial experimental results indicate that the highest electron temperature of the formation region was approximately 8 eV, the electron density of the colliding-and-merging region was approaching 10 20 m −3 , and the ion temperature reached about 40 eV.