Two-stage γ ray emission via ultrahigh intensity laser pulse interaction with a laser wakefield accelerated electron beam

In this study, we investigate the generation of twin γ ray beams in the collision of an ultrahigh intensity laser pulse with a laser wakefield accelerated electron beam using a particle-in-cell simulation. We consider the composed target of a homogeneous underdense preplasma in front of an ultrathin solid foil. The electrons in the preplasma are trapped and accelerated by the wakefield. When the laser pulse is reflected by the thin solid foil, the wakefield accelerated electrons continue to move forward and pass through the foil almost without influence from the reflected laser pulse or foil. Consequently, two groups of γ ray flashes, with tunable time delay and energy, are generated by the wakefield accelerated electron beam interacting with the reflected laser pulse from the foil as well as another counter-propagating petawatt laser pulse behind the foil. Additionally, we study the dependence of the γ photon emission on the preplasma densities, driving laser polarization, and solid foil.     

激光尾场中被加速电子的动能研究

为了研究在激光驱动的尾场中被加速电子的动能,采用粒子模拟方法,得到了决定电子最大动能的尾场势的最大值和最小值,讨论了等离子体尾波静电势的最大值和最小值及其与激光脉冲长度和强度之间的关系。结果表明,捕获电子最大能量与脉冲激光强度成正比,激光脉冲长度是激光波长的10倍时电子获得的能量最大。     

强激光驱动的运动电场加速质子的研究

为了研究激光辐射压驱动的运动电场中加速质子的相关问题,对强激光与等离子体相互作用过程进行了理论分析,并采用2维粒子模拟方法,对理论分析结果进行了数值模拟验证。结果表明,当超短超强激光脉冲与处在背景等离子体前方的薄固体平靶相互作用时,在固体靶后部形成一个由电子层-离子层组成的双层结构,在激光辐射压的不断推进下,双层结构在背景等离子体里以一定速度传播形成一个运动电场;在背景等离子体中的质子被这个运动电场捕获并能加速到很高的能量,质子的最大能量达到20GeV。理论分析结果与2维粒子模拟结果符合得很好。     

不同激光脉冲驱动的尾场中正电子加速的研究

为了研究在激光驱动的尾场中被加速正电子的动能,采用数值模拟方法,得到了非对称sine脉冲、flat-top脉冲和Gaussian脉冲驱动的尾场中被加速的正电子的能量。结果表明,非对称sine脉冲驱动尾场中正电子得到的能量比flat-top脉冲和Gaussian脉冲驱动尾场中得到的能量高一些。