Energy dependence of the stopping power of MeV 16O ions in a laser-produced plasma

The energy dependence of the stopping power of 16O ions in a laser-produced plasma target was experimentally investigated in the projectile energy range of 150–350 keV/u. In order to produce the target plasma a Q-Switched Nd-glass laser was focused onto a small lithium hydride (LiH) pellet. The plasma electron temperature and the electron line density were 15 eV and 2×1017 cm−2, respectively. The energy loss of 16O ions in the plasma was measured by a time-of-flight (TOF) method. We found that the stopping power in the plasma agreed with the theoretical estimation based on a modified Bohr equation with correction at low velocities. In this evaluation, the effective charge of the projectile was calculated by means of rate equations on the loss and capture of electrons. It has been also found that in this projectile energy range the stopping power of the 16O ions in the plasma still increases with decreasing projectile energy, while it decreases in cold equivalent.