Energy loss of 6 MeV/u ⁵⁶Fe ions in a partially ionized helium plasma has been for the first time measured as a function of incident charge state ranging from 21+ to 25+. Enhancement of the energy loss of the ions in the discharge plasma has been observed over that in cold helium gas. The enhanced stopping of ¹⁶O ions with energies of \sim 0.2 MeV/u in laser ablated LiH plasma has been also observed over that in cold matter. Theoretical calculation proposed by Sigmund reproduces the energy dependence of the experimental stopping power of the ¹⁶O ions in the plasma.

PACS numbers: 34.50.Bw, 52.20.Hv, 52.40.Mj, 52.50.Jm