First spectroscopic study of HFRC plasma

Abstract

Abstract 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 Hγ (n = 5 → n = 2; 434.04 nm). Doppler broadening of an O III (2s22p(2P0)3p → 2s22p(2P0)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 Hβ (n = 4 → n = 2; 486.14 nm) (Dβ) and Hγ (Dγ) 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 1020 m−3, and the ion temperature reached about 40 eV.