The ion response to relativistic electron bunches in the so called bubble or blowout regime of a laser-plasma accelerator is discussed. In response to the strong fields of the accelerated electrons the ions form a central filament along the laser axis that can be compressed to densities 2 orders of magnitude higher than the initial particle density. A theory of the filament formation and a model of ion self-compression are proposed. It is also shown that in the case of a sharp rear plasma-vacuum interface the ions can be accelerated by a combination of three basic mechanisms. The long time ion evolution that results from the strong electrostatic fields of an electron bunch provides a unique diagnostic of laser-plasma accelerators.

The full set of linearized Fokker–Planck kinetic equations with Landau collision terms have been solved as an initial-value problem for equilibrium electron-ion plasmas. This work is a generalization of the nonlocal transport theory by Bychenkov et al. [Phys. Rev. Lett. 75, 4405 (1995)] to both electron and ion components with frequency-dependent responses. Transport closure relations have been obtained for the complete set of electron and ion fluid equations which are valid over the full range of particle collisionality and for an arbitrary ionic charge. The well-known limits of collisionless and strongly collisional plasma transport theory have been recovered. Practical fits based on the numerical calculations have been introduced for nonlocal and frequency-dependent ion transport coefficients.

The nonlinear evolution of ion acoustic fluctuations in the presence of a uniform electron drift which exceeds the sound speed and electron–ion collisions is investigated using a collisional particle simulation model for parameters relevant to laser-heated plasmas. The results indicate that for the one-dimensional case, strong electron–ion collisionality can lead to a significantly higher saturation level of the fluctuations, which is comparable to the saturation level in the two-dimensional collisionless regime. This relatively high turbulence level can act to enhance heat flux inhibition and strongly influence the absorption and transport properties of laser-produced plasmas.

Solid target experiments carried out on copper targets with both p- and s-polarized 130 fs Ti:Sapphire laser pulses at intensities of 3 x 10 16 W/cm 2 indicate the presence of hot electron jets with electron energies of 80 to over 250 keV and cone angles of the order of 10 degrees at the higher energies with directions dependent on the incident polarization. For comparison, studies on an Argon cluster jet targets with 50 fs duration Ti:Sapphire laser pulses at vacuum intensity of 10 17 W/cm 2 indicated no detectable hot electron jet emission with electron energies above 50 keV. A 2D PIC simulation of the p-polarized solid target interaction predicts features similar to those observed experimentally.

Photoionized plasmas created in the interaction of short linearly polarized x-ray pulses with a gaseous medium are characterized and discussed in the context of experiments with femtosecond FEL pulses. The electron distribution function in these plasmas remains strongly anisotropic due to unique plasma atomic and kinetic processes until such time that electron-electron collisions are able to thermalize the distribution. The relaxation of nonequilibrium photoionized plasmas is studied by using Monte-Carlo simulations which account for photoabsorption, elastic electron collisions, impact ionization of atoms, and atomic excitations. The dispersion properties and instabilities of a fully ionized x-ray-produced plasma is described. The photoionized plasma is found to be subject to a two-stream type of instability which has a growth rate comparable in magnitude to the plasma frequency and is therefore expected to have a dramatic effect on the evolution of the plasma. We performed 3D PIC simulation of this photo-ionization two-stream (PITS) instability. A model for electromagnetic field generation and emission resulting from the interaction of a short x-ray laser pulse with a gas jet is proposed. This is used to explore the effect of the thermo-EMF at the edge of a plasma characterized by an anisotropic electron energy distribution which results from the photoionization of the gas. Terahertz pulse generation from the plasma is predicted.

A regular procedure is proposed for finding the solution to a linearized kinetic equation for charged particles with the Landau collision integral in a plasma with large Z. The expression for longitudinal permittivity of a collisional plasma, which is obtained using this procedure for the entire range of frequencies and wavenumbers, as well as the collision parameter, is transformed to the known expressions in the corresponding asymptotic limits. The nonlocal transport equations for small perturbations are also formulated for arbitrary relations between the characteristic space and time scales of the plasma; these relations considerably extend the limits of applicability for previously developed theories.

We present a new interference pattern based scheme for the cell diagnostics. In this approach a biological cell is illuminated by a spherical light source. The interference pattern, that is created by the unscattered incident light and the light that is scattered by a cell, is used for cell diagnostics.A three-dimensional computational code (AETHER) for solving the full set of Maxwell's equations with the Finite-Difference Time-Domain (FDTD) method has been employed to numerically determine the interference light intensity pattern between the unscattered incident light and the scattered light. Features of the interference intensity patterns that are obtained for different cellular parameters and structures are discussed. We have numerically shown that the interference intensity pattern can replace the purely scattered light patterns currently used in cell diagnostics.

An analytical solution is found to the vortex electron anisotropic hydrodynamic equations that describe the nonlinear evolution of the long-wavelength Weibel instability. The presented analytical approach shows that the long-wavelength Weibel instability saturates without a decrease in the temperature anisotropy in the single-mode regime due to the rotation of the anisotropy axes. The generated magnetic field is circular-polarized, and its amplitude varies periodically in time.