The dynamic form factor for Thomson scattering with a non-Maxwellian (super-Gaussian) electron velocity distribution is analytically and numerically studied for the first time. Both the ion and electron features of the spectra for a. 1 are found to be affected strongly. For the ion feature, the use of the usual theoretical spectra with the assumption of a Maxwellian distribution for fitting the measured Thomson scattering spectra may have resulted in some errors in calculating the plasma parameters in high-Z plasmas irradiated with high intensity light. However, it is impossible to use the ion feature of the measured spectra alone to deduce the form of the electron distribution. For the electron feature, the spectral shape (in particular the peak amplitude) changes sensitively with the distribution index. It would be possible to detect the super-Gaussian distribution by simultaneously measuring the ion and electron features of the spectra.

Abstract. A numerical solution to the linearized ion Fokker-Planck (FP) equation is presented. By reducing the FP equation to an eigenvalue problem via moment expansion of a perturbed ion distribution function, the frequencies and damping rates of ion-acoustic waves and the specific heat ratio are calculated. Numerical calculation shows that this technique is very efficient, as ion Landau damping is negligible in comparison with collisional damping.

The intermittent chaos in the multicomponent plasmas with negative ions has been investigated experimentally. The phenomena are modeled as a variant of classical type-I intermittency, which is studied numerically in detail. The experimental results confirmed the numerical prediction of 1/f noise, the probability distribution of laminar length, and the scaling law of Lyapunov exponents. A qualitative explanation on the intermittent chaos in the multicomponent plasmas with negative ions is also given.

Transition radiation from a beam of hot electrons generated in ultraintense laser plasma interaction is theoretically studied. The total radiation is separated into two parts: one is incoherent transition radiation (ITR), the other is coherent transition radiation (CTR). The spectrum of ITR just depends on the particle velocity distribution in the beam. The angular distribution of ITR varies from sin2 u, and approaches the angular distribution of the beam when the hot electron temperature increases from the nonrelativistic limit (T《mc2) to the ultrarelativistic limit (T》mc2). The spectrum of CTR is dependent on the particle configuration as well as their velocities. Any microbunching in the beam can greatly enhance the CTR intensity at the microbunching frequency, from which the dominant heating process can be inferred. The effects of target thickness and hot electron temperature on CTR intensity are also calculated. The simplified model shows that the CTR intensity decreases with the increase of the target thickness, and increases with the hot electron temperature. The divergence of the beam can broaden the CTR spectrum.

The spectrum of transition radiation from a relativistic hot electron beam with the Boltzmann energy distribution is theoretically studied. The spectrum of transition radiation is separated into two parts: one is the incoherent spectrum, the other is the coherent spectrum. The results show that the temperature and total number of hot electrons can be obtained from the incoherent spectrum, and that the perturbation wave number in an electron bunch can be deduced from the coherent spectrum, from which the dominant heating process can be studied.

Hot electrons and optical emission are measured from the rear surface of a metallic foil. The spectra of the optical emission in the near infrared region have a sharp spike around the wavelength of the incident laser pulse. The optical emission is ascribed to coherent transition radiation due to microbunching in the hot electron beam. It is found that the optical emission closely correlates with the hot electrons accelerated in resonance absorption.

The propagation of a dust-ion-acoustic wave (DIAW) wave down the steep density gradient in an inhomogeneous diffusive dusty plasma is experimentally studied. It is observed that the presence of the dust enhances the plasma inhomogeneity. The phase velocity of the DIAW increases rapidly with distance and becomes supersonic. The interplay between the effects of the density nonuniformity and collisional damping results in the continuous transition of the relative amplitude of the DIAW from damping to growth. The experimental data are in agreement with theoretical prediction and confirm the importance of density-dependent ion-dust collisions.

Detailed measurements of gold plasmas produced with 0.351mm laser light are reported. The temporal and spatial variations of ZTe are obtained in the case that pump intensities are 6.5 31013 and 1.431014 W/cm2. The experimental results are qualitatively consistent with two nonlocalized absorption models.

Dynamic screening of the Coulomb interaction is included to calculate electron transport coefficient (electron thermal conductivity) in the fluid limit for an unmagnetized plasma. Calculated results show that the dynamic screening effect can reduce electron thermal conductivity and may be important for low-Z plasma with very large electron-ion temperature ratio (Te/Ti≥103).

The influence of super-Gaussian velocity distributions on the ion feature of Thomson scattering off two-ion plasmas is studied. The analytical solution to the dispersion equation shows that although both the frequencies of the two (fast and slow) ion-acoustic waves increase with the index of the super-Gaussian, the slow wave is more weakly dependent on the index due to the screening of the light ions. In the case that plasma can sustain two lightly damped ion-acoustic waves, the inferred plasma parameters such as electron temperature and plasma temperature ratio may suffer some errors without consideration of super-Gaussian electron velocity distributions. Since the relative intensity between the resonant peaks of the fast and slow waves is sensitive to the super-Gaussian index, the super-Gaussian velocity distributions may be measurable with Thomson scattering off laser-heated two species ion plasmas.