A new approach to measure stimulated Brillouin scattering threshold based on the output energy characteristic of stimulated Brillouin scattering optical limiting is proposed. The stimulated Brillouin scattering threshold or its exponential gain, Gth, can be accurately and conveniently determined by the intersection point of linear-fitting lines of the output energy below and above the threshold. The values of Gth in CS2 and FC-72 for different wavelengths and interaction lengths are measured in Continuum's Nd:YAG Q-switched laser and its frequency-doubled system. We show that Gth for transient regime is larger than that for steady state, and increases with the pump wavelength and the interaction length.

The field distribution and the restraint effect of multipactor and plasma discharge on the periodic triangular surface have been theoretically and experimentally analyzed. It has been found by computational and simulative analysis that the periodic profile can quickly restrain or weaken multipactor and plasma discharge in low pressure within several microwave periods. Considering the field enhancement, increasing the slope angle, advancing the electric field, and lowering the frequency can enhance the multipactor suppression. X-band giga-watt high power microwave experiment with 20 ns short pulse was conducted. It was demonstrated that the periodic profile can effectively improve the breakdown threshold and slower the speed of tail erosion.

The acceleration of electrons by very intense lasers in vacuum is studied for different forms of laser pulses: finite plane and three-dimensional laser pulses. The latter case is treated by introducing an approximation of the laser frequency as a function of the Cartesian components of the wave number. Various examples which lead to high accelerations of electrons are given.

For the future, we have to develop new sources of energy. These new sources may be based on nuclear fusion with magnetic confinement (as with the ITER experiment) or with a new concept based on inertial confinement. The European community plans to build a facility (HiPER project) which is dedicated to reaching high gain with cryogenic targets, and to test the concepts of target mass production and rep rate shots. The cryogenic system for the 1st phase experiments in HiPER is based on the cryogenic system developed for the French facility Laser MegaJoule (LMJ). The latter must be modified and upgraded for direct drive targets. In particular the target must be protected from the radiation flux from the vacuum vessel by a thermal shroud. In addition, the LMJ system must be equipped with a thermal system to allow layering of the fusion fuel to take place. The new developments concern a leak tightness thermal shroud for direct drive and a fast shroud retractor able to allow the laser shot within few milliseconds.

We describe a funnel cone for concentrating an ion beam on a target. The cone utilizes the reflection characteristic of ion beams on solid walls to focus the incident beam and increase beam intensity on target. The cone has been modeled with the TRIM code. A prototype has been tested and installed for use in the 350-keV K+ NDCX target chamber.

Experiments on ion acceleration by irradiation of ultra-thin diamond-like carbon (DLC) foils, with thicknesses well below the skin depth, irradiated with laser pulses of ultra-high contrast and linear polarization, are presented. A maximum energy of 13 MeV for protons and 71 MeV for carbon ions is observed with a conversion efficiency of ~10%. Two-dimensional particle-in-cell (PIC) simulations reveal that the increase in ion energies can be attributed to a dominantly collective rather than thermal motion of the foil electrons, when the target becomes transparent for the incident laser pulse.