Effective laser–induced removal of co–deposited layers from plasma–facing components in a tokamak

An experimental set–up and spectroscopy diagnostic method for laser–induced fuel removal and decomposition of co–deposited layers on plasma–facing components from tokamaks are described. For irradiation of a graphite limiter tile from the TEXTOR tokamak Nd:YAG 3.5-ns pulse laser with a repetition rate of 10 Hz and single pulse energy of up to 0,8 J at 1,06 μm has been used. The spectroscopy system allowed recording of spectra in the visible wavelength range including . The evolution of CII and Dα spectral lines was observed pulse–by–pulse during the co–deposite removal. The efficient ablation of the 45 μm thick co–deposit occured after approximately 50 laser pulses.