Research Of The Generation And Application Of Attosecond Electron Trains From Ultra-intense Laser-Cone Target Interaction

As a tool for observing and steering electronic motion outside atomic nucleus,the attosecond physics helps explore and control processes of the microcosm.However,the intensity of attosecond pulses achieved is insufficient to induce nonlinear phenomena,which largely limits the applications of the attosecond physics.The next step of the attosecond physics witnesses an accelerating progress of high-quality attosecond light sources.Similarly,radioisotope-based neutron sources are also widely applied,but their intensities are too low to largely extend the exposure duration.The investigation of fusion neutron sources will help solve the problem.First,we propose to generate enhanced spatially-periodic attosecond electron bunches through the interaction of an ultraintense laser with a cone target.By using two-dimensional particle-in-cell simulations,we obtain electron bunches with an average density of about 10 nc and cut-off energy up to 380 MeV.We also consider the influence of laser and cone target parameters on the bunch properties.The laser oscillating field pulls out the cone surface electrons periodically and accelerates them forward via laser pondermotive force.It indicates that the attosecond electron bunch acceleration and propagation could be significantly enhanced by attaching a plasma capillary to the cone tip.By using three-dimensional particle-in-cell and Monte Carlo simulations,we then investigate the generation of high-brightness attosecond X-ray trains via Thomson backscattering of a counterpropagating laser pulse off attosecond bunches generated from the interaction between an ultraintense laser pulse and a cone target.The simulation results show that the photon number rises by 5 times by using a cone target when comparied with the case using a channel.Meanwhile,the X-ray brightness also increases.We also consider the influence of laser and target parameters on X-ray train properties.This scheme obtains high brightness,compact X-ray pulse trains,which may be widely applied in studies of electric dynamic in the atomic-scale.Finally,we investigated laser-driven ion acceleration and compression from a thin DT foil in a double-cone configuration.By using two-dimensional particle-in-cell simulations,it is shown that a double-cone structure can effectively guide,focus and strengthen the incident laser pulses,resulting in enhanced acceleration and compression of D+ and T+.Due to ion Coulomb repulsion and the effective screening from the external laser electric fields,the transverse diffusion of ions is significantly suppressed.As a result,the peak energy density of the compressed ions exceeds 2.73?1016 J/m3,which is about five order-of-magnitude higher than the threshold for high energy density physics,1011 J/m3.Under this condition,DT fusion reactions are initiated and the neutron production rate per volume is estimated to be as high as 7.473?1035 /m3 s according to Monte Carlo simulations,which is much higher than that of the traditional large neutron sources,and may facilitate many potential applications in future.