Ultrashort Pulse Laser Matter Interaction In Electronic Behavior

The behavior of electron in ultrashort laser-plasma interaction was studied in this thesis. It is included the energy spectrum and angular distribution of hot electrons generated by ultrashort laser-solid interaction, the effect to electron behavior of electrical conductivity of target material, the hot electron activities and plasma characteristics in various plasma scale length, the rule of electron movement related to the high harmonic generation in gas, the excelled calculation about the condition of high harmonic generation, the study of electron spectrum and ion spectrum generated by Coulomb explosion in laser cluster interaction. Although there are different characteristics among these topics, the electron behavior and those plasmas characteristics related to it are the key points we pay attention to. Through these experimental and theoretical studies, we can see more insight into the electron behavior of two hot topics in intense field physics--fast ignition laser fusion and high harmonic generation. The main content we studied and results as following: 1. The building and parameters of electron magnetic spectrometer which can be used to measure the hot electron produced by laser interact with target material directly was described in detail. The energy spectrum of hot electron produced by ultrashort intense laser interact with solid target was measured with this electron spectrometer. In the laser intensity of 5 x iO W 1cm2 , the maximum energy of hot electron is over 500keV. The spectrum presents two-temperature Maxwell distribution. For the first time we measured the charge separation potential and its effect to the hot electron spectrum. Besides these, another conceptive design for wide energy rang electron spectrometer was expressed in this paper. 2., The investigation of the effects of the laser polarization on acceleration mechanisms was studied by observing outgoing fast electrons and in-going fast electrons generated by p- and s-polarized ultrashort laser pulses obliquely incident on an overdense plasma with and without a corona preplasma. We did systematic experimental studies on behaviors of fast electrons in ultrashort pulse laser-plasmas produced by 150 fs, p- and s-polarized obliquely incident laser pulses at 5x10? Wcm2J.Lm2. We demonstrated experimentally, for the first time, that both s- and p-polarized lasers can generate jet emission of fast electrons, although their acceleration mechanisms are different for s- and p-polarized irradiation. This provides new insights on acceleration mechanisms of fast electrons in ultrashort pulse laser-plasma interaction. Furthermore, the behaviors of in-going fast electrons into the target have also been studied, for the first time at a non- relativistic irradiance, using Bremsstrahlung radiation for s- and p-polarized irradiation. The in-going fast electrons produced by p-polarized laser pulses were found to be collimated in the normal direction, whereas the in-going fast electrons produced by s-polarized laser pulses appeared to emit randomly. The angular divergence of out-going hot electrons is inversely proportional to the electron energy. 3 The energy absorption, the number of hot electron emission and the hot electron energy spectrum produced during the interaction of P-polarized laser pulse with intensity of 8x i015 Wim2cm2on metallic and dielectric target materials were studied. In metallic target the char...