Experimental study about angular distribution of protons emitted from thin solid target irradiated by supershort laser

Proton generation and angular distribution produced by supershort laser pulse irradiating thin solid Au target were investigated. The experiment was performed on the SILEX-Ⅰ laser facility. CR39 was mounted 3.3 cm behind the target to record the protons from the target. How the laser intensity and laser contrast ratio influenced the mechanism of proton acceleration was studied by analysing the proton angular distributions. The primary acceleration mechanism of proton is sensitive to the prepulse. When the prepulse is weak, the primary proton acceleration is target normal sheath acceleration. When the prepulse is strong, most protons is primarily accelerated in the front of target.