The Particle Acceleration And Harmonic Generation In The Interaction Of Ultra-short Intense Laser Pulses With Plasmas

In recent years,with the rapid development of ultrashort intense laser pulse and the mechanism of the fast ignition in laser fusion, the study of the interaction of ultra-short intense laser pulses with plasmas,which is motivated primarily by the fast ignition scheme of inertial confinement fusion,has received more and more attention. This thesis is devoted to studying those issues relevant to the interaction of ultra-short intense laser pulses with plasmas.Using the theoretical model of generating mono-energetic proton beams from the foils irradiated by intense laser pulses, we obtained the necessary condition and the balance condition of proton acceleration. Also by the 1D PIC simulations, we compared the effect on proton acceleration by changing the intensity and duration of initial laser pulse and the target thickness and density. It is shown that the proton energy increases with the laser pulse duration in the range of the stable acceleration, but it is saturated as the protons become relativistic. The acceleration follows the mechanic principle, the proton energy increases with the laser intensity while it decreases when the target thickness and density increase. When intensity exceed the perfect one, mono-energetic proton beams can not be obtained because the electrons are pushed away. The result is consistent with the simulation.We studies a strong harmonic generation in the interaction of two counter-propagate pulses with a foil target. When the thin target is irradiated by high-contrast circularly polarized laser pulse, the light pressure push high-density plasma forward。At the same time, because of the role of charge separation field, the ion beam and electron beam bunch well in longitudinal direction, and generate the plasma mirror with a forward movement of the relativistic speed. Then incidenting a probe laser pulse on the plasma mirror in the opposite direction, produces strong monochrome N-order harmonics by Doppler shift, with the new duration of pulses compressed to 1/N of the original one. This paper also discusses the effect of the laser and plasma parameters on plasma mirror movement which influences the order of harmonics, and the effect of the stability of the relativistic plasma mirror on harmonics.The attosecond x-ray pulse which is produced by the interaction between the laser pulse and the relativistic electrons is studied in this paper. The attosecond x-ray pulse is generated by Thomson backscattering from the relativistic electrons. It also discusses the effect of the plasma parameters on the attosecond x-ray. The wavelength of attosecond x-ray pulse becomes shorter when the frequency of the laser or the velocity of the relativistic electrons increases. We gained the"water window"x-ray by selecting the appropriate laser and plasma parameters. This paper also discusses the effect of relativistic electrons density and density grad on the translation efficiency.The thesis is organized as follows. The first chapter gives a brief introduction of research background and developing process of interaction of laser pulse with plasma. In the second chapter, we investigate mono-energetic proton beams from the foils irradiated by intense laser pulses. Then, in the third chapter, a strong monochromatic harmonic generated in the interaction of two counter-propagating laser pulses with plasmas is explored. Chapter four presents our result of the attosecond X-ray pulse generated by the interaction of two counter-propagate pulses with a foil target. As the conclusion, in the last chapter, we briefly summarize the total subject and give an expectation for the future work.