Study on interaction processes between heavy ion beams and high-density plasma

We measured the energy loss of protons and oxygen ions (4.3 MeV/u or 6 MeV/u) in a z-pinch discharge helium plasma having an electron density of 1018-1019 cm-3. By supposing that the ions were fully-stripped in the plasma, we evaluated the Coulomb logarithm for the plasma. The Coulomb logarithm for the plasma was found to be twice larger than that for cold equivalent. We also estimated the mean charge of iron and xenon ions in the plasma by combining the energy loss data obtained previously and the above Coulomb logarithm. We confirmed that the increase in the mean charge due to density effects became more important when the electron density of the plasma was above 1019 cm-3. (author)