The effects of ion motion on the generation of short-cycle relativistic laser pulses during radiation pressure acceleration are investigated by analytical modeling and particle-in-cell simulations. Studies show that the rear part of the transmitted pulse modulated by ion motion is sharper compared with the case of the electron shutter only. In this study, the ions further modulate the short-cycle pulses transmitted. A 3.9 fs laser pulse with an intensity of 1.33×1021W cm-2is generated by properly controlling the motions of the electron and ion in the simulations. The short-cycle laser pulse source proposed can be applied in the generation of single attosecond pulses and electron acceleration in a small bubble regime.
When a relativistic laser pulse of high photon density interacts with a specially tailored thin foil target,a strong torque is exerted on the resulting spiral-shaped foil plasma,or"light fan".Because of its structure,the latter can gain significant orbital angular momentum(OAM),and the opposite OAM is imparted to the reflected light,creating a twisted relativistic light pulse.Using such a relativistic LaguerreGaussian(LG)laser interaction with a solid foil,we can get intense high order vortex harmonics.Besides that,proton acceleration using LG laser and hollow screw-like drill in plasma using LG laser are studied.All interaction scenarios are demonstrated by particle-in-cell simulation as well as analytical modeling,and should be verifiable in the laboratory.As important characteristics,twisted relativistic light pulse has strong torque and ultra-high OAM density,which may lead to many more new effects.
SHI YinSHEN BaiFeiZHANG XiaoMeiWANG WenPengXU ZhiZhan
