Large angle scattering of 100 keV C4+ and C6+ on He without charge exchange

Reaction channels with single-, double-, and no-charge exchange have been measured in hard collisions of 100 keV 13C4+ and 13C6+ on He0 with projectile scattering angle covering the range of 3-5 degrees. The hard collisions produce recoils with sufficient kinetic energies, so that even the neutral recoil atoms can be detected with MCP detectors. The fraction of no-charge changing collisions are substantially larger than predictions from CTMC calculations. These results are of interest for the plasma ion temperature measurements by van Blokland et al., who used 7 degree scattering of 30 keV He0 to measure the ion temperature of the low Z plasma fuel in the TEXTOR tokamak, but observed contributions from scattering from the high Z impurities without charge exchange. Proper corrections depend on the fraction of the scattering without charge exchange