Spectroscopic study of hydrogen reflection at modified tungsten surface

Doppler-spectroscopy study of hydrogen atoms reflected from a fuzzy tungsten (W-fuzz) surface was performed to investigate the effects of the W surface morphology upon the hydrogen particle reflection in low energy region less than 300 eV. The reflected atoms from the W-fuzz surface contributed to a tail part of Ha spectra measured in the vicinity of the surface negatively biased in a magnetized hydrogen plasma. Time evolution of the spectral intensity exhibited an increase of the hydrogen particle reflection coefficient correlated to the continuous removal of the porous fuzz structure due to the hydrogen-plasma bombardment. The initial particle reflection coefficient of hydrogen atoms from the porous W-fuzz surface was 50% lower in comparison to a smoother W surface following the removal of the fuzz structure.