A beam combination laser with stimulated Brillouin scattering-phase conjugate mirrors (SBS-PCMs), which is expected to produce a high output energy and power with a repetition rate over 10 Hz, is a candidate for a practically useful laser fusion driver in the future. In order to develop the beam combination laser with SBS-PCMs, it is necessary to control the phase of each SBS wave whose phases are known as inherently random. We have proposed a new phase control technique and demonstrated experimentally that the relative phase difference between two SBS waves can be controlled to a certain value and locked to it with an accuracy less than λ/4. Additionally we have proposed and demonstrated a new technique to preserve the pulse shape of the SBS wave. Based on these experimental results, we have proposed two schemes of the new schemes for the high repetition and high energy/power beam combination laser system (laser fusion driver) using the SBS-PCMs of amplitude division and wave-front division techniques, which can operate with repetition rate over 10 Hz, in this paper.

The high-order harmonic generation process was studied using laser pump pulses of different duration, down to 7 fs. The time profile of this kind of pulse corresponds to a few optical cycles at the fundamental frequency, and therefore a cycle-to-cycle variation of the maximum amplitude occurs. These facts violate the adiabatic approximation of the generation process, giving rise to new aspects of the physical process. The comparison of results with pulses in the two regimes are reported and discussed. The modeling of the complete generation and propagation process in three dimensions is also presented.

The self consistent electrostatic field due to plasma inhomogeneities and associated with free expansion of a plasma into a vacuum is evaluated in the framework of two-fluid hydrodynamics and the corresponding generalized Rieman's self-similar solution found. The case of an adiabatic expansion is also discussed and the results obtained are applied to a laser produced plasma with a characteristic electron temperature of 1 keV and a characteristic time scale of 1 nsec.

Efficient electron acceleration by a linearly chirped ultrashort laser pulse in vacuum is investigated using the particle swarm optimization method. By applying this method for optimizing the initial parameters of the laser pulse, a pronounced increase in final energy gain of the electron is obtained compared to that expected from the successive optimization method. Our results also suggest that the value of the optimal chirp parameter is independent of laser polarization and the energy gain could be insensitive to the sign of this parameter when the initial phase is optimally adjusted. In addition, utilizing the chirped laser pulse with optimized conditions for acceleration of an electron bunch reveals that the energy spectrum is shifted to considerably higher energies and the spatial distribution is significantly improved in a polarization-dependent manner.

Cumulative effects in gases accompanying hydrodynamic motion due to powerful laser energy deposition deal with the problems of high-speed jet generation and plasma heating. In the present paper, on the basis of experimental simulation and theoretical analysis we investigate the behavior of a cumulative ring shock wave near the axis of symmetry. Such a shock wave arises after the energy deposition into the volume of a gas having the form of a thin torus.

We report experiments that were carried out at the inductive storage machine GIT-4 with wire arrays. The tungsten wire array parameters were the following: the mass per centimeter was equal to 370 μg/cm, the length was 4 cm, and the initial radius was 0.2 cm. When the wire array current was 1.5 MA, the rise time was 100 ns and the total radiation energy was 50 kJ at the 80–100–kJ energy transferred to the wire array.

In the interaction of short-laser pulses with a solid density target, pre-plasma can play a major role in ion acceleration processes. So far, complete analysis of pre-plasma effect on the ion acceleration by ultra-short laser pulses in the radiation pressure acceleration (RPA) regime has been unknown. Then the effect of pre-plasma on the ion acceleration efficiency is analyzed by numerical results of the particle-in-cell simulation in the RPA regime. It is shown that, for long-laser pulses (τp > 50 fs), the presence of pre-plasma makes a destructive effect on ion acceleration while it may have a contributing effect for short-laser pulses (τp < 50 fs). Therefore, the 35 fs (20 fs) laser pulse can accelerate ions up to 40 MeV (55 eV), which is almost two (three) times larger in energy rather than use of a 100 fs pulse with the same pre-plasma scale length.

A systematic investigation of the longitudinal fields excited in a plasma by a short, dense beam of positrons is carried out using two-dimensional, cylindrical geometry, particle-in-cell code simulations. In particular, we examine the behavior of the accelerating and decelerating fields of the wakefield as a function of beam charge, radius, length, and plasma density. The parameters are chosen to be consistent with those employed in current and future experiments designed to elucidate the physics of positron beam–plasma interactions.

Implosion experiments performed at Centre d'Etudes de Limeil-Valenton in the indirect drive scheme using the two-beams Nd:glass laser facility Phebus at the energy level = 6 kJ (blue light) are presented. A final density of compressed DT close to 100 ρ0 has been obtained; it has been deduced from radiochemistry of the activated silicon atoms in the pusher. The best irradiance uniformity on the microballoon was evaluated to = 15% rms. Phebus has also been equipped with an optical fiber oscillator to study the effect of a smoothing technique on coupling processes: It appeared that at 0·53 μm absorption efficiency is increased by =15–20%. With the eight-beams Octal laser, hydrodynamic instabilities development in accelerated planar targets has been investigated both for direct and indirect drives; the mixing zone detected at the light-heavy interface does not present visible bubble-and-spike like structures and is less developed in the indirect configuration. Atomic physics in laser plasmas is also deeply studied; a particular effort has been made on absorption spectroscopy, a powerful diagnostic of ionization dynamics in cold and dense plasmas. Experiments have been realized either in multilayered targets or using rear-side X-ray emission of thin Au foils to heat the samples. To reach fuel ignition conditions, more powerful lasers, in the range of megajoule, will be needed. Their design needs further technological developments to reduce the capital cost in $/W. At Limeil, we work mainly on high-damage threshold optical coatings, using the sol-gel process, high-quality, low-cost mirror fabrication, using the replica technics, and incoherent laser pulse generation for beam smoothing.

In indirect-drive inertial confinement fusion, the radiation symmetry must be controlled for the achievement of hotspot ignition. The radiation symmetry is of great importance. In this paper, we investigate the drive asymmetry of the M-band (2–5 keV) radiation emitted from an Au holhraum wall by using the three-dimensional view-factor code IRAD3D. Analysis of the M-band flux drive at the Shenguang-III laser facility shows that it is asymmetric and that the asymmetry varies with time. For a given cross section over the pole, the initial M-band flux asymmetries are P2 = 11.59, P4 = 1.41, and P6 = −0.64%. When the asymmetries are artificially added to a symmetric radiation drive, the position of the deuterium-tritium (DT) ice/gas interface is asymmetric for a National Ignition Facility capsule in 1D simulation. This means that M-band flux asymmetry can lead to implosion asymmetry even if the total radiation is symmetric. Pure CH and Si-doped CH capsules are considered. The results show that a mid-Z dopant can partly reduce the asymmetry. However, the asymmetry is still very large. Thus, it is necessary to study the M-band flux asymmetry and its influence on the implosion symmetry.

Krypton Large Impulse Thruster (KLIMT) project was aimed at incremental development and optimization of a 0.5 kW-class plasma Hall Effect Thruster in which, as a propellant, krypton could be used. The final thermally stable version of the thruster (the third one) was tested in the Plasma Propulsion Satellites (PlaNS) laboratory in the Institute of Plasma Physics and Laser Microfusion (IPPLM) in Warsaw as well as in the European Space Agency (ESA) propulsion laboratory in the European Space Research and Technology Centre (ESTEC).

During final measurement campaign, a wide spectrum of parameters was tested. The plasma potential, electron temperature, electron concentration, and electron energy probability function in the far-field plume of the thruster were measured with a single cylindrical Langmuir probe. Faraday probes were used for recording local values of ion current. Using several collectors in different locations and moving them on the surface of a sphere, the angular distribution of the expelled particles was reconstructed which was a local measure of beam divergence. Angular distribution of ion flux as measured with a central Faraday probe was parameterized with krypton mass flow rate, voltage, coil current ratio, and the cathode mass flow rate. Beam divergence measurements with Faraday probes as well as plasma parameters derived from Langmuir probe seem to be consistent with our understanding of the operating envelope. Obtained results will serve as a baseline in the design of plasma beam structure diagnostics system for the PlaNS laboratory.

The behavior of matter under intense soft X-radiation is considered. An impulse of X-radiation (about 2–1012 W/cm2) produced a strong shock wave in the sample. The velocity of this shock wave was measured. A shock compression about 300 GPa in the lead target was achieved.

We report the first studies on the formation of an elongated plasma column suitable for X-ray laser experiments, using a gas puff target irradiated with a high-power laser. The gas puff targets, produced by pulsed injection of a small amount of gas from a high-pressure solenoid valve through a nozzle in the form of a slit, have been characterized by optical interferometry and X-ray backlighting. The formation of a hot plasma column up to 30-mm-long is demonstrated. The spatial uniformity of the column was monitored by means of an X-ray pinhole camera. XUV spectra measurements for SF6 gas puff targets show predominant 3–2 line of hydrogenic fluorine (λ = 8.1 nm), however, only linear increasing of its intensity with the target length was observed.

An ICF plant is designed to use nuclear-driven flashlamp-pumped solid-state lasers as fusion drivers. It is proposed to use a separated fission reactor with aerosol fuel to drive alkali metal excimer flashlamps as the pumping source for solid-state lasers. The first observation of nuclear-excited sodium excimer emission at 436 nm in a TRIGA reactor with 815 Torr of He-3 and 60 Torr of sodium vapor (at T = 924 K) is reported. The experiment demonstrates the feasibility of a nuclear-driven alkali metal excimer lamp. The compatibility of alkali metal excimers with different laser crystals is evaluated for driver efficiency. High overall laser efficiency ensures large fractional output power extraction from nuclear fusion by this plant. The suitability of laser crystals for the ICF plant is also presented.

The concept and experimental results of a microwave-excited elliptical excimer lamp are presented in this paper. The plasma excimer photons are excited at one focus, and the absorber is placed at the second focus. Two elliptical microwave cavities with different eccentricities were tested to study the excitation and characteristics of such an elliptical excimer lamp. The results show that it can be a high-efficiency, narrow-band incoherent vacuum–ultraviolet (VUV)-to-near-infrared photon source. The potential applications of such an excimer lamp, especially with tunable vibronic solid-state and diamond thin film growth, are discussed.

Sensitivity analysis is a powerful first-order mathematical technique that identifies the major reactions, the effects of errors in rate constants, pressure effects, and temperature effects in a plasma chemistry type model. Several methods of sensitivity analysis have been discussed in the literature. This paper describes the successful implementation of the state transition matrix method to the sensitivity analysis of a plasma chemistry model using both e-beams and ions for excitation. The ion excited plasma study is important to the field of nuclear-pumped lasers. This model examines 8 species and 37 reactions.

In this work, the Saha equation is solved using atomic data provided by means of a new relativistic-screened hydrogenic model based on analytical potentials to calculate the ionization state and ion abundance for LTE iron plasmas. The plasma effects on the atomic structure are taken into account by including the classical continuum lowering correction of Stewart and Pyatt. For high density, the Saha equation is modified to consider the degeneration of free electrons using the Fermi–Dirac statistics instead of the Maxwellian distribution commonly used. The results are compared with more sophisticated self-consistent codes.

The application of laser accelerated ion beams in Hadron therapy requires ion beam optics with unique features. It has been shown that due to the spectral and spatial distribution of laser accelerated protons a lens based focusing system has advantages over aperture collimated beam formation. We present a compact ion optical system with therapy applications, based on Gabor space charge lenses for collecting, focusing and energy filtering the laser produced proton beam. For a full therapy solution, a scenario based on three space charge lenses is presented. In this very compact beam line an aperture is foreseen for energy selection.

A review of theoretical works on the laboratory X-ray laser (XRL) research performed at RFNC–VNIITF for the last few yearsis presented. Three potential photopumped XRL schemes with relatively short laser wavelengths (44, 23, and 64 Å) have been investigated. Theoretical studies of lasing plasma parameters for some of the published recombination and resonantly photopumped XRL schemes have been performed using our kinetics and line-profile codes.

Laser ablation of graphite materials in the presence of an external magnetic field is studied with the use of the newly developed HEIGHTS-PIC particle-in-cell code and compared with both theoretical and experimental results. Carbon plumes behavior controlled by a strong magnetic field is of interest to evaluate the plume shielding effects to protect the original exposed target from further damage and erosion. Since intense power deposition on plasma facing components is expected during Tokamaks loss of plasma confinement events such as disruptions, vertical displacements event, runaway electrons, or during normal operating conditions such as edge-localized modes, it is critical to better understand the evolving target plasma behavior for more accurate prediction of the potential damage created by these high-energetic dumps which may not be easily mitigated without loss of structural and functional performance of the plasma facing components. Numerical experiments have been performed to provide benchmarking conditions for the HEIGHTS-PIC simulation package originally designed to evaluate the erosion of the Tokamak surfaces, splashing of the melted/ablated-vaporized material, and transport into the bulk plasma with consequent plasma contamination. Evolving target plasma temperature and density are calculated and compared with measured reported values available into literature for similar conditions and show good agreement with the HEIGHTS-PIC package predictions.