Attenuation of high-energy neutral hydrogen beams in high-density plasmas

Beam stopping cross section and shine-through for neutral hydrogen beam injection into fusion plasmas have been calculated by using recommended cross sections presently available for atomic processes including multistep collision processes involving excited states. The shine-through thus obtained agrees well with recent experiments of JT-60U. The present calculations show that the multistep processes play a crucial role in the stopping of high-energy neutral hydrogen beams in high-density plasmas. Analytical fits to the stopping cross sections and fitting parameters are also presented for plasma impurities with nuclear charge and Z = 26.