Dynamics of plasma ions motion in ultra-intense laser-excited plasma wakes

The effects of heavy ions and protons motion in an ultra-intense laser-driven plasma wake are compared by rebuilding a plasma wake model. It is shown that with the same laser and plasma background electron density n(0), the heavy ions' motion suppresses wake-field resonant excitation less than the protons' motion in their own plasma wake. Though heavy ions obtain more kinetic energy from the plasma wake, its energy density is less than that of the protons due to the ion density being far less than the proton density. As a result, the total energy of heavy ions obtained from the wake-field is far less than that of protons. The dependence of the kinetic energy and the energy density of protons and heavy ions on n(0) is discussed.