Multistage, e-beam-pumped, 100 J-class KrF laser installation “GARPUN” is described with the emphases to high-power laser beam control and target irradiation experiments. The ablation pressures in the megabar range were measured and hydrodynamic flow was investigated both experimentally and by numerical simulations for laser intensities up to 5×1012 W/cm2, pulse duration of 100 ns, and focal spot diameter 150 μm. Graphite-diamond phase transformation under laser loading was observed by dynamic and Raman scattering methods. Some approaches to the fast ignition inertial confinement fusion, using the simultaneous amplification of long and short laser pulses in KrF drivers, are considered.

The presence of an axial magnetic field in a laser beat wave accelerator enhances the oscillatory velocity of electrons due to cyclotron resonance effect leading to higher amplitude of the ponderomotive force driven plasma wave, and higher energy of accelerating electrons. The axial magnetic field inhibits the transverse escape of electrons and thus causes a growth of the interaction length. The surfatron acceleration of electrons also shows a similar enhancement. A surfatron transverse magnetic field deflects the electrons parallel to the phase fronts of the accelerating wave keeping them in phase with it. However, the electron continues to move away radially.

In this article, we study the effect of various parameters on the estimation of radiation temperature inside an indirect drive ICF hohlraum and also study the hydrodynamics of aluminum and gold foils driven by the hohlraum radiation. A multigroup one-dimensional, radiation hydrodynamic code is used for this study. Opacities are calculated using a screened hydrogenic average atom model. We also investigate the opacities of Au-Sm and Au-Gd mixtures. It is shown that the mixing of two high Z materials can lead to an enhancement in the Rosseland means, which is of direct interest in indirect-drive inertial confinement fusion. The radiation temperature inside a cylindrical hohlraum is seen to be strongly dependent on the number of frequency groups used. One group radiation transport underpredicts the radiation temperature. It is shown that erroneous results can be obtained if the space mesh in the hohlraum wall is not fine enough. The spectrum of the radiation inside the hohlraum is seen to be different from Planck, especially in the high-energy range. This may lead to preheating of the target. Hydrodynamics of an aluminum foil driven by the hohlraum radiation is also presented in this article. A scaling law for the radiation-driven shock-wave speed in the gold foil is obtained.

Inertial Confinement Fusion is a promising option to provide massive, clean, and affordable energy for mankind in the future. The present status of research and development is hindered by hydrodynamical instabilities occurring at the intense compression of the target fuel by energetic laser beams. A recent patent combines advances in two fields: Detonations in relativistic fluid dynamics (RFD) and radiative energy deposition by plasmonic nano-shells. The initial compression of the target pellet can be decreased, not to reach the Rayleigh–Taylor or other instabilities, and rapid volume ignition can be achieved by a final and more energetic laser pulse, which can be as short as the penetration time of the light across the pellet. The reflectivity of the target can be made negligible as in the present direct drive and indirect drive experiments, and the absorptivity can be increased by one or two orders of magnitude by plasmonic nano-shells embedded in the target fuel. Thus, higher ignition temperature and radiation dominated dynamics can be achieved with the limited initial compression. Here, we propose that a short final light pulse can heat the target so that most of the interior will reach the ignition temperature simultaneously based on the results of RFD. This makes the development of any kind of instability impossible, which would prevent complete ignition of the target.

The anomaly at laser plasma interaction at laser pulses of TW to PW power and ps duration led to a very unique generation of quasi-neutral plasma blocks by a skin layer interaction avoiding the relativistic self-focusing. This is in contrast to numerous usual experiments. The plasma blocks have ion current densities above 1011 A/cm2 and may be used for a fast ignition scheme with comparably low compression of the deuterium tritium (DT) fuel. The difficulty is that a very high energy flux density E* of the ions is necessary according to the hydrodynamic theory (Bobin, 1971, 1974; Chu, 1972). This theory did not include the later discovered collective effect for the stopping power of the alpha particles. One problem is being discussed, whether the Bethe-Bloch binary collision theory or the collective collision theory of Gabor has to be applied. The inclusion of the collective effect results in a reduction of the threshold value of E* for ignition by a factor of about fife.

A theoretical model is developed to describe self-similar plasma expansion into vacuum with two different electron temperature distribution functions. The cold electrons are modeled with a Maxwellian distribution while the hot ones are supposed to be non-thermal obeying a kappa distribution function. It is shown that ion density and velocity profiles depend only on cold electron distribution in early stage of expansion whereas ion acceleration is mainly governed by the hot electrons at the ion front and is strongly enhanced with the proportion of kappa distributed electrons. It is also found that when the kappa index is decreasing, the critical value of temperature ratio Teh/Tec, limiting the application of quasi-neutrality, becomes larger than the $5 + \sqrt {24} \approx 9.9$ value obtained in the two-electron Maxwellian Bezzerides model [Bezzerides, B., Forslund, D. W. & Lindman, E. L. (1978). Phys. Fluids21, 2179–2185].

We present the temporal and spatial characterization of X-ray sources (at ~1 keV) driven by a 200 TW, 30 fs, 800 nm laser pulse on SILEX-I laser facility at Research Center of Laser Fusion. For laser copper foil interaction with laser intensity between 6 × 1018 W/cm2 and 3 × 1019 W/cm2, the X-ray images show cone-like jet structures. While the yield of X-rays is strongly dependent on the laser intensity, the plasma expansion length is weakly dependent on the laser intensity, and the open angle of the cone-like jet is not correlated to the laser intensity. The formation of the jet structure is attributed to the plasma transverse confine by the self-induced quasi-static magnetic field. An X-ray pedestal 4 ns preceding the main pulse was observed. The correlation between X-ray pedestal and collimated proton beam generation was found.

Annealed and fine polished Ag and Cu samples are irradiated for 25, 50, 75, and 100 shots with a Q-Switched Nd:YAG laser in air and under high vacuum ~10−6 Torr. The irradiated samples are investigated under scanning electron microscopy, which reveals the formation of laser induced ripples structures with spacing 10 µm to 25 µm. Careful analysis revealed that the ripple spacing is not only dependent on laser wavelength, target properties, but also on the number of laser shots. It is also observed that ripples spacing varies from center to edge of the thermal damage zone. Two-fold spacing is measured near the edge compared to spacing at the center of the crater. Anisotropic stresses and stress waves (shock waves) are guiding the laser induced heat energy through particular channels. Splashing cones are developed with the increase in the laser shots. More theoretical investigations are needed to study the laser ripple periodicity in the context of laser shots effect.

The results of a high-resolution processing, based on techniques of fractal dimension analysis, of experimental data from earlier experiments on the linear Z-pinches are presented, which prove the electric current-carrying plasmas to be a random fractal medium. The basic building block of this medium is identified to be an almost-closed helical filamentary magnetoplasma configuration (we call it heteromac). The heteromacs are coupled together through long-range self-sustained filamentation and, thus, form a dynamical percolating network with dissipation. The results (i) extend recently identified phenomenon of the 3D large-scale (up to several centimeter size) helical filamentary plasma structures (Kukushkin et al. 1994, 1995, 1997a) in plasma focus gaseous discharges to the case of Z-pinch gaseous discharges and (ii) provide a novel view into the dynamics of Z-pinch's necks, plasma spikes, and magnetic bubbles as well as into generic features of electric current-carrying plasmas varying from low-electric current laboratory plasmas to cosmic plasmas. This covers about 30 orders of magnitude of length scale and suggests unprecedented opportunities for interpolating between and extrapolating from well-understood phenomena. A magnetoplasma universe model is suggested.

Linear transformer driver (LTD) technology is actively developed at the Institute of High Current Electronics in Tomsk, Russia. This technology is being examined for use in high current high voltage pulsed accelerators. Recent development of high voltage low inductance capacitors and low inductance switches enabled to achieve ~100 ns rise time of the LTD output pulse. This technique allows one to eliminate intermediate pulse forming sections, used in the present accelerator technology, which would keep the footprint of an LTD accelerator small. LTD based drivers are currently considered for many applications, including future very high current Z-pinch drivers for inertial confinement fusion, medium current drivers with adjustable pulse length for isentropic compression experiments, and finally relatively low current accelerators for radiography and X-pinches. In this article, we present the design and test results for a new LTD stage, that operates at 100 kV charging voltage. Current amplitude up to 850 kA with ~140 ns rise time was obtained on a 0.05 Ω load. Stack of the LTD stages can be easily assembled in series or in parallel, thus providing voltage or current multiplication, respectively. Design of multi-mega-volt and multi-mega-ampere generators becomes straightforward with the LTD technology.

Based upon the Ammosov-Delone-Krainov ionization model, it is shown that two-color laser interaction with neutral gas generates strong ionization currents, which lead to electromagnetic emission at terahertz frequency when the gas density is at proper values. The emission efficiency depends on the difference of the phases between the fundamental and its second harmonic. The intensity ratio between the two pulses also affects the emission strength. An optimum intensity ratio has been found within our parameter region. The above ionization current theory is in agreement with one-dimensional particle-in-cell simulations with field ionization included.

One of the numerous applications of the ICAN laser using the advantage of fiber optics with chirped pulse amplification (CPA), is the scheme of side-on initiation of a nuclear fusion flame in solid density fuel with laser pulses of shorter than picosecond (ps) duration and power in the petawatt (PW) and higher range. The ICAN Fiber optics has special advantages with the potential that >900 PW spherical laser pulses may ignite the proton reaction with 11B (HB11) without the problem of dangerous radioactive radiation. Though secondary reactions can be estimated very roughly, the feasibility of a power station with the necessary energy gains can be concluded.

We study the details of a gradual change in electron properties from those of a nearly-free-electron (NFE) metal to those of a strongly-coupled plasma, in ultrashort pulse energy deposition in solid metal targets. Time scales shorter than those of a target surface layer expansion are considered. Both the case of an optical laser (visible or near infrared wavelengths range) and of a free electron laser (vacuum ultraviolet or X-ray) are treated. The mechanisms responsible for the change in electron behavior are isochoric melting, lattice charge disordering, and electron mean free path reduction. We find that the transition from metal to plasma usually occurs via an intermediate stage of a charge-disordered solid (solid plasma), in which ions are at their lattice sites but the ionization stages of individual ions differ due to ionization from localized bound states. Charge disordered state formation is very rapid (typically, few femtoseconds or few tens of femtoseconds). Pathway to charge-disordered state differs in simple metals and in noble metals. Probabilities are derived for electron impact ionization and 3-body recombination of a bound ionic state in solid-density medium, applicable both in metal and in plasma regime. An evolution of energy coupling between electron and ion subsystems, from metallic electron-phonon (e-ph) to plasma electron-ion (e-i) coupling, is considered. Substantial increase in coupling parameter is expected as a result of charge disorder.

Analytical far-field expressions for the transverse electric mode and transverse electric magnetic mode terms, and the energy flux distributions of vortex Airy beams are derived based on the vector angular spectrum of the beam and the stationary phase method. The physical pictures of vortex Airy beams from the vectorial structure are illustrated and the energy flux distributions are demonstrated in far-field. The influences of the beam parameters, especially the exponential factor, on the energy flux distributions of vortex Airy beams and its transverse electric mode and transverse electric magnetic mode terms are discussed. This work provides a new understanding of the propagation behaviors and applications of a vortex Airy beam.

This work presents an investigation of the self-focusing of a high-power laser beam having cosh Gaussian intensity profile in a collissionless plasma under weak relativistic-ponderomotove (RP) and only relativistic regimes and its effect on the excitation of electron plasma wave (EPW), and particle acceleration process. Nonlinear differential equations have been set up for the beam width and intensity of cosh Gaussian laser beam (CGLB) and EPW using the Wentzel-Kramers-Brillouin and paraxial-ray approximations as well as fluid equations. The numerical results are presented for different values of decentered parameter ‘b’ and intensity parameter ‘a’ of CGLB. Strong self-focusing is observed in RP regime as compared with only relativistic nonlinearity. Numerical analysis shows that these parameters play crucial role on the self-focusing of the CGLB and the excitation of EPW. It is also found that the intensity/amplitude of EPW increases with b and a. Further, nonlinear coupling between the CGLB and EPW leads to the acceleration of electrons. The intensity of EPW and energy gain by electrons is significantly affected by including the ponderomotive nonlinearity. The energy of the accelerated electrons is increased by increasing the value of ‘b’. The results are presented for typical laser and plasma parameters.

The late-time growth rate of the Richtmyer–Meshkov instability was experimentally studied at different Atwood numbers with two-dimensional (2D) and three-dimensional (3D) single-mode initial perturbations. The results of these experiments were found to be in good agreement with the results of the theoretical model and numerical simulations. In another set of experiments a bubble-competition phenomenon, which was observed in previous work for 2D initial perturbation (Sadot et al., 1998), was shown to exist also when the initial perturbation is of a 3D nature.

New extensions of the chirped pulse amplification (CPA) scheme designed specially for petawatt Ti:Sapphire lasers are considered. The two new schemes support a spectral bandwidth sufficient for 20 fs pulses and a temporal contrast of 1012. The Double CPA scheme consists of two CPA stages with an intermediate temporal pulse filtering for temporal contrast improvement. The scheme of Negative–Positive CPA amplification takes advantage of consecutive saturated amplification of down chirped and up chirped pulses. This allows a suppress imprint of gain narrowing, which usually limits the spectral bandwidth at the multi-terawatt power level, and reach the bandwidth in excess of 50 nm without using any direct spectral shaping of the pulse.

Laser matter interaction in the regime of super-intense and ultra-short laser pulses is discovering common interests and goals for plasma and elementary particles physics. Among them, the electron laser wakefield acceleration and the X/γ tunable sources, based on the Thomson scattering (TS) of optical photons on accelerated electrons, represent the most challenging applications. The activity of the Intense Laser Irradiation Laboratory in this field will be presented.

The present status of the development of a high-power KrF laser system, Ashura, is described. The main amplifier has generated 710 J (95 ns) at the pumping density of 1·lMW/cm3 with the wall plug efficiency of 2·0%. Maximum power of 9·0 GW (200 J/22 ns) per beam has been obtained from the beam lines of six-time pulse multiplexing. Power density of 1 × 1014 W/cm2 has been achieved on target with a 10−6 pre-pulse.

The Institute of Plasma Physics and Laser Microfusion's (IPPLM) Hall effect thruster (Krypton Large IMpulse Thruster, KLIMT) is a 500 W class plasma engine with a mean diameter of discharge channel of 42 mm. KLIMT was developed within ESA/PECS project aiming to provide relatively small thruster for satellites that would be able to effectively operate with krypton propellant. Being several times less expensive than xenon, which is regarded as a propellant of choice for electric propulsion of electrostatic type, krypton since years has been suggested as an attractive alternative. In this paper, a design as well as performance tests of the laboratory model of KLIMT are discussed. It is shown that precise adjustment of magnetic field topography results in the stable operation of the thruster in wide range of operating conditions providing similar thrust and specific impulse production for both propellants. Maximum thrust produced with the use of xenon and krypton reached about 16–17 mN for mass flow rate of 1.15–1.2 mg/s resulting in specific impulse in the range of 1300–1500 s (13–15 km/s). However, for krypton the anode efficiency drops by ~10% in comparison with xenon. For krypton plasma beam divergence as measured by an average half-angle with respect to the beam axis was found to remain within the range of 19–23° for the whole set of the examined operating conditions. The reported characteristics are reasonable for Hall thruster of the discussed size and power.