Spectroscopy Study of Hydrogen Atoms Reflected From Tungsten Surface in a Magnetized Plasma

Spectroscopy study of reflected hydrogen atoms from a W surface under plasma bombardment was performed by measuring the Hα emission spectra. The contribution from the reflected hydrogen atoms was confirmed at the outermost part of the Doppler-broadened Hα spectra by suppressing the background light from the atomic and molecular excitations in the plasma. A mechanism of the collisional excitation with an H
₂
molecule is proposed to explain the excitation of the reflected atoms to the n = 3 level in the region outside of the plasma column, where the background signal from the plasma was largely reduced. The measured spectra were compared with the reconstructed spectral profiles by Monte Carlo simulations using the atomic collision amorphous target code. This paper presents a promising method to collect fundamental data related to the recycling of hydrogen atoms near the edge region of fusion devices in the energy range below a few 100 eV.