Gizzi Leonida A, Boella Elisabetta, Labate Luca, Baffigi Federica, Bilbao Pablo J, Brandi Fernando, Cristoforetti Gabriele, Fazzi Alberto, Fulgentini Lorenzo, Giove Dario, Koester Petra, Palla Daniele, Tomassini Paolo
Intense Laser Irradiation Laboratory, INO-CNR, Pisa, Italy.
INFN, Sez., Pisa, Italy.
Sci Rep. 2021 Jul 2;11(1):13728. doi: 10.1038/s41598-021-93011-3.
The interaction of ultraintense laser pulses with solids is largely affected by the plasma gradient at the vacuum-solid interface, which modifies the absorption and ultimately, controls the energy distribution function of heated electrons. A micrometer scale-length plasma has been predicted to yield a significant enhancement of the energy and weight of the fast electron population and to play a major role in laser-driven proton acceleration with thin foils. We report on recent experimental results on proton acceleration from laser interaction with foil targets at ultra-relativistic intensities. We show a threefold increase of the proton cut-off energy when a micrometer scale-length pre-plasma is introduced by irradiation with a low energy femtosecond pre-pulse. Our realistic numerical simulations agree with the observed gain of the proton cut-off energy and confirm the role of stochastic heating of fast electrons in the enhancement of the accelerating sheath field.
超强激光脉冲与固体的相互作用在很大程度上受到真空 - 固体界面处等离子体梯度的影响，该梯度会改变吸收情况，并最终控制被加热电子的能量分布函数。据预测，微米尺度长度的等离子体能够显著提高快电子群体的能量和数量，并在薄箔片的激光驱动质子加速中发挥重要作用。我们报告了近期关于在超相对论强度下激光与箔靶相互作用产生质子加速的实验结果。我们发现，当用低能量飞秒预脉冲照射引入微米尺度长度的预等离子体时，质子截止能量增加了两倍。我们逼真的数值模拟与观测到的质子截止能量增益相符，并证实了快电子的随机加热在增强加速鞘层场中的作用。
