Rate of energy change of proton traversing in hot high-Z plasmas due to nuclear collision

The rate of change of the energy of the projectile proton moving in hot Au plasmas due to the elastic binary collision between the projectile and the target ion at different density and temperature is studied based on the potential from ionic sphere model. It is found that the proton may obtain energy when its kinetic energy is less than the plasma temperature, which means that the proton and the target ion are in thermal equilibrium when the kinetic energy of the proton is around the plasma temperature. The well known model (Phys. Rev. 126, 1 (1962)) is found not to work in hot high-Z plasmas. The reason for this is explored and found relevant to the very small thermal velocity of the high-Z ion compared with the projectile. This leads to the failure to ignore the dependence of the Coulomb logarithm upon the relative velocity between the projectile and the target ion. A revised model is proposed by us and found to work well while the revised model (Phys. Rev. A 29, 2145 (1984)) is unsatisfactory in this case.