Enhanced Proton Acceleration by Irradiating an Ultrathin Target with a Low Contrast Laser Pulse

【作者】 王大辉； 寿寅任； 马文君； 颜学庆；

【机构】 西北核技术研究所； 北京大学；

【摘要】 We report a simulation study on proton acceleration driven by ultraintense laser pulses with low contrast( 10^8) containing amplified spontaneous emission(ASE).It’s found in hydrodynamic simulations that when the thickness of the targets typically in the range of hundreds nanometers matches the ASE,a plasma density profile with a smooth gradient for tens of micrometers at the target front and a sharp gradient at the target rear is formed.This asymmetry is attributed to the regime that the target,more precisely an overdense plasma spike,is pushed as a whole by ablation pressure in the forward direction exceeding the expansion velocity of plasma at the target rear.Due to self-focusing at the target front and a large sheath field at the target rear,2 D particle-in-cell(PIC) simulations reveal that the proton energy can be enhanced by a factor of 2 compared to the case of micrometer-thick targets.更多还原

【Abstract】 We report a simulation study on proton acceleration driven by ultraintense laser pulses with low contrast( 10^8) containing amplified spontaneous emission(ASE).It’s found in hydrodynamic simulations that when the thickness of the targets typically in the range of hundreds nanometers matches the ASE,a plasma density profile with a smooth gradient for tens of micrometers at the target front and a sharp gradient at the target rear is formed.This asymmetry is attributed to the regime that the target,more precisely an overdense plasma spike,is pushed as a whole by ablation pressure in the forward direction exceeding the expansion velocity of plasma at the target rear.Due to self-focusing at the target front and a large sheath field at the target rear,2 D particle-in-cell(PIC) simulations reveal that the proton energy can be enhanced by a factor of 2 compared to the case of micrometer-thick targets.更多还原