Session CO2 - Laser Accelerators; Ultraintense Laser Applications.
ORAL session, Monday afternoon, November 15
Room 203, SCC
Recent experiments at the University to Michigan are helping to elucidate the dynamics of electrons and protons produced by high-intensity-laser interactions with thin-film solid targets by examining proton beam characteristics from increasing thicknesses of Mylar and aluminum. The proton beam energy and spatial profile are found to vary with target thickness as well as initial target conductivity. Half the peak proton energy is observed from Mylar targets as compared to aluminum targets as well as a much sharper reduction in proton energy with increasing target thickness. These differences originate from the strong inhibition of the hot-electron forward and return currents in the initially highly resistive material, which limits electron recirculation and thus proton energy from the target rear surface. In addition, evidence from energy and beam profile data supports the existence of target independent 5-MeV-maximum-energy beam from the target front surface. Other effects on beam profile due to target conductivity such as beam hollowing, originating from the electrothermal instability, are also presented.