The TRIDENT laser system at the Los Alamos National Laboratory is being used for fundamental experiments which study the interaction of self-focusing, stimulated Raman scattering (SRS) and stimulated Brillouin scattering (SBS) in a near-diffraction-limited (single) laser hot spot in order to better understand the coupling between these plasma instabilities. The diffraction limited beam mimics a single hot spot found in speckle distributions that are typical of random or kinoform phase plates (RPP or KPP) used for spatial smoothing of laser beams. A long scale length, hot plasma (∼1 mm, ∼0.6 keV) is created by a separate heater beam, and the single hot spot beam is used to drive parametric instabilities. The focal plane distribution and wave-front of the interaction beam are characterized, and its intensity can be varied between 1014–1016 W/cm2. The plasma density, temperature, and flow profiles are measured using a gated imaging spectroscopy of collective Thomson scattering from the heater beam. Results of the laser and plasma characterization, and initial results of backscattered SRS, SBS, and beam steering in a flowing plasma are presented.

Taking into account the stochastic excitation of the atoms (as quantum structures), we can suggest an absolutely new conception of a wide spectrum of processes in a femtosecond laser produced plasma. The electromagnetic fields being achieved with the modern laser technique exceed intraatomic fields by several orders. This fundamentally changes the physics of their interaction with the atomic structures. The atom effectively transforms the energy of radiation falling on it into fluxes on the nucleus. Quantum systems spin interaction with vector potential field being to play the essential role.

The precise measurements of the spectral line profiles near the short-wavelength limit of the Lyman series of Al are reported. The spatially resolved narrow-band spectra were attributed to macroscopic plasma parameters by using the results of 1D and 2D hydrodynamic plasma modeling. The gradual merging and broadening of the spectral lines Al Lyε–θ was compared to the synthetic spectra produced by atomic physics codes. The discrepancies between the experimental and theoretical data indicate the limits for applicability of standard theoretical models.

The experiments measuring the density of DT mixture compressed in indirect drive targets (X-ray targets) were conducted on the ISKRA-5 facility. The density was determined from the line broadening of H- and He-like Ar doped in DT-gas as a diagnostic substance. A series of three experiments with the X-ray targets having different shell thickness of capsule filled with DT + Ar mixture were carried out. In two of the three experiments, radiation spectra of Ar were recorded and the density of compressed gas was determined. The analysis of the experimental results for the X-ray target with a 280-μm diameter and a 7 μm wall thickness revealed that the density of the compressed gas may be estimated as ∼1 g/cm3.

The first experiments to study the shell's controlled asymmetry of capsule with DT-fuel in a highly symmetrical X-ray field, which is obtained inside a spherical hohlraum, were implemented. The asymmetry results from the coating of one hemisphere with the additional layer of material. The main goal of the experiment was to define the value of the capsule asymmetry, allowing us to experimentally obtain the neutron yield, which would be very different from the yield obtained in the experiment with the spherically symmetrical shell having the same mass as the asymmetrical one. It was shown that the shell asymmetry of ∼50% leads to the ∼(2–4) times reduction of the neutron yield as compared with the symmetrical shell. 2D calculations of the asymmetric capsule compression, using the MIMOZA-ND code, were conducted. The calculations demonstrated that the compression of targets, when exploding pusher regime occurs has a complicated character. The computational neutron yield, and the delay of the neutron generation time are in good agreement with the experimental data.

Here we study the problem of a focused laser beam propagation in plasma with the initial density, which is much higher than the critical one. The Helmholtz equations, together with the equations of single fluid hydrodynamics, with the relativistic ponderomotive force were solved. It was shown that the stable waveguide with the cross-section of wavelength size was formed when plasma was affected by the laser radiation with the intensity exceeding the critical one while the laser radiation pulse was as long as (10–100) ps.

A novel approach for injection of a freestanding target into an ICF chamber is described which could significantly reduce both the dead volume of the target system and the fill time of cryotarget. The extremely short flight time of a target inside the ICF target chamber (less than 100 ms) allows one to keep the quality of the cryolayer up to the very moment of target irradiation. The possibility of improving the quality of the inner surface of the cryogenic layer by using the target illumination by the electron beams during the free fall of the target in the fusion chamber is also discussed.

In the previous design, the maximum drive radiation temperature was 4 MK or 350 eV (Holstein 1996). Different beam configurations gave roughly the same uniformity with the NIF-size cavity. Our best configuration used four cones of beams illuminating three rings. An integrated 2D simulation pointed out that the symmetry was good enough to reach a gain of ten. Two evolutions took place in the design of our MJ laser. We moved from a capsule adapted to 4 MK (L1000) to another one adapted to 3.5 MK (L1215) in order to minimize the parametric instabilities (the cavity size is almost the same). This new capsule also has a better hydrostability according to the “classical modelling” (Lindl 1995). The second evolution is a simplification of the target chamber. We restricted ourselves to two major configurations for indirect drive (two-ring and three-ring configurations). Therefore, only three cones of beams are necessary instead of five cones in the first design. Finally, the number of holes in the chamber is 80 instead of 100.

The interaction of powerful laser and X-ray pulses with planar low average density (0.5–10 mg/cm3) porous agar-agar targets was experimentally studied. At a laser power density of ∼5 × 1013 W/cm2 (λ = 1.054 μm) the laser light absorption and following energy transfer processes, as well as dynamics of produced plasma were investigated in detail with a variety of optical and X-ray diagnostic methods. Volume absorption is shown to occur in experiments with laser-irradiated agar targets. An extended laser energy deposition region filled with hot (0.8–1 keV) plasma is formed inside a porous target. The laser light absorption efficiency is as high as ∼80%. The emission of 2ω0 and 3ω0/2 harmonics from laser-produced plasma is observed over the time of the laser pulse even with agar targets of 0.5 mg/cm3 average density. Characteristics of energy transfer in low-density porous media are measured in experiments on illumination of agar targets by laser pulses or X rays emitted by a thin Cu converter. The hydrodynamic mechanism is responsible for the energy transfer in laser-illuminated porous targets and the radiative energy transfer seems to be dominant in the case of X-ray irradiation. The experimental data are in reasonable agreement with predictions of a developed theoretical model describing the hot plasma layer formation and the two-stage homogenization process within the illuminated porous targets.

2D arrays of laser diodes were developed and investigated under QCW operating conditions. Output power and energy density up to 1 kW/cm2 and 0.45 J/cm2 (at pulse duration 0.5 ms) were measured at the wavelength 810 nm. The spectral composition of radiation, shape of the output pulses, and far-field and near-field radiation zones were examined under various pumping parameters. The kinetics of the temperature profiles in monolithic QCW AlGaAs/GaAs linear bars and 2D arrays, emitting at the wavelength 810 nm was modeled numerically. Quasi-CW and CW operation under various pump parameters were considered as a function of a heat sink design. A calculation model was used to interpret the experimental dependences of the output parameters of the arrays on the pump conditions for application in the solid-state laser driver project. The limit of total power conversion efficiency of diode lasers was analyzed in respect of the threshold current density, series resistance and external differential quantum efficiency. The estimated maximum value of 75% was obtained for the present technological level of the diode lasers production. The corresponding limit of the output optical power density of 2D laser array was defined around 10 kW/cm2.

We have studied a suite of cylindrical, polystyrene targets, both unperturbed and with mode-28, 1.5 μm initial-amplitude sinusoidal perturbations imposed azimuthally along the target length. All targets are driven by direct laser illumination at 3ω using the University of Rochester OMEGA laser facility. Our numerical simulation and experimental data demonstrate the proof of principle for direct-drive studies of complex hydrodynamic phenomena in convergent geometry. We obtain high-quality, time-dependent data, that demonstrate good implosion symmetry and against which numerical simulations show promising agreement within currently assessed error bars. Our results identify operational space for continuing experiments.

Modification of the growth of scattering processes in the case of multiple beam irradiation compared to single beam irradiation has been investigated in a preformed plasma using Thomson scattering of a short wavelength probe beam, and spectral and temporal analysis of reflected and transmitted light. First observations of the reduction of the amplitude of ion acoustic waves associated with simulated Brillouin scattering, amplification of the amplitude of electron plasma waves associated with stimulated Raman scattering, and transfer of energy between crossing beams with same frequency in a flowing plasma under crossed beam irradiation are reported.

A time-resolved X-ray conversion efficiency campaign was conducted at CEA/Limeil–Valenton on the PHEBUS laser, with Au planar targets. The calibrated diagnostic DEMIXART has measured X-ray emissions driven by shaped laser pulses. The results have been analyzed with the “physicist” 1D1/2 hydrodynamical code CHIVAS, where improved transport coefficients have been implemented. The influence of the degeneracy and solid/liquid corrections on various parameters is shown. Other significant effects due to focal spot shapes and lateral conduction are quantified with the FCI2 hydroradiative code of CEA/DRIF.

Hydrodynamic instabilities, such as the Rayleigh–Taylor and Richtmyer–Meshkov instabilities, play a central role when trying to achieve net thermonuclear fusion energy via the method of inertial confinement fusion (ICF). The development of hydrodynamic instabilities on both sides of the compressed shell may cause shell breakup and ignition failure. A newly developed statistical mechanics model describing the evolution of the turbulent mixing zone from an initial random perturbation is presented. The model will be shown to compare very well both with full numerical simulations and with experiments, performed using high power laser systems, and using shock tubes. Applying the model to typical ICF implosion conditions, an estimation of the maximum allowed target, in-flight aspect ratio as a function of equivalent surface roughness, will be derived.

Targets of thin (0.1 μm) Al buried beneath 0.1 μm plastic overlay have been irradiated by the 350 fs CPA pulse from the 248 nm Titania KrF laser at irradiances of 1017 W/cm2. We report a study of the radiative properties of the Al plasma using X-ray emission spectroscopy. It is demonstrated that short-pulse irradiation of buried-layer targets can produce a plasma with close to solid densities and electron temperatures of several hundred eV. We examine the effect that a long duration (5–50 ns) low intensity (∼5 × 108 W/cm2) prepulse has on the measured values of electron density and temperature. The experimental technique will allow the determination of the accuracy of LTE radiative calculations in this new regime of extremely high material energy density.

Since 1973, research into the problem of laser thermonuclear fusion has been carried out at VNIIEF. For this purpose, laser iodine facilities ISKRA-4 and ISKRA-5 with the peak radiation power up to 100 TW have been created. In the present work, the main stages of these facilities creation, approaches to the selection of the pumping sources, working media, optical scheme, radiation focusing system, the system of the pumping sources energy feed, laser radiation, and plasma parameters diagnostics methods are shown. There are also presented types of the targets, filled with DT-gas, in which the high temperature plasma is formed and its parameters are studied. Data on values of neutron yield, of X rays in wide energy range, degree of implosion, and data on mix of heavy and light layers of matter are presented as well.

An investigation of a monochromatic point X-ray source of photon energy ∼5 keV was carried out. The source was set up using a laser produced Al plasma as a cathode and a point-tip Ti anode. Optimum parameters of the diode were determined from experimental measurements of X-ray intensity dependence on laser pulse energy, applied accelerating voltage, and distance between target (cathode) and anode, using Nd:glass laser pulses (FWHM 30 ns) of 2 mJ to 4 J energy. Electron temperature characterization of the target plasma was also performed from the XUV emission spectrum (5–80 Å). Parameters of X radiation in Ti K-shells are (1) spectral brightness of ∼1020 photons/cm2-sec-sr-keV, (2) spatial size ∼300 microns, and (3) X-ray pulse duration less than 20 ns.

Solitons are generated by injecting energy provided by high power laser devices into a quiescent ICF plasma. The data obtained by laser fusion show a change δne in electronic density profile focused by ponderomotive force of laser radiation near the critical layer where wp = w0, wp being the plasma frequency and w0 the laser frequency. This change that has a structure of soliton type, becomes as a solution of a nonlinear Schrödinger equation (NLS), solved as an inverse problem by means of the inverse scattering transform with one eigenvalue invariant in time, and representative of wave eigenvector. Electrical currents are given in function of the above mentioned change in the density profile of electrons and an average velocity of such electrons corresponding to a nonmaxwellian electronic velocity distribution. The z component of heat flow is a consequence of electrical currents generated, the generalized electrical field to classical transport, and the generalized expression of vectorial heat flow developed by Haines.

Particle-in-cell (PIC) simulations show that an anisotropic electron velocity distribution is demonstrated by ultraintense laser pulses in underdense plasmas. Recently, it is reported that the anisotropy has been experimentally demonstrated in laser-produced plasmas. It is also pointed out that gigagauss magnetic fields are generated by ultraintense laser pulses. We have already published that the Weibel-type electromagnetic instabilities can be theoretically excited by electrons in a velocity distribution with anisotropic temperature. If these electromagnetic waves are excited, the target may have a possibility not only to give rise to a new type of energy loss mechanism but also to influence the implosion characteristics. In this work, we present PIC simulation of the interaction of ultraintense laser pulses with plasmas. Intense self-generated magnetic fields is produced by the mechanism of Weibel instability in underdense plasmas.

The first experimental study of the propagation of electrons created by an intense laser in shock-compressed matter has been performed with the VULCAN laser facility at the Rutherford Appleton Laboratory, to investigate one of the fundamental phases of the fast ignitor concept for inertial confinement fusion. Plastic plane targets were irradiated on one side with two pulsed laser beams, each with I ≈ 1014 W/cm2, t ≈ 2 ns, E ≈ 80 J per pulse, to generate a planar shock wave; on the opposite side of the target, a chirped pulse amplification (CPA) laser beam (I ≈ 1016 W/cm2, t ≈ 3 ps, E ≈ 10 J) was focused to generate the fast electrons. The results show an increase of hot electron penetration in compressed matter with respect to an ordinary one. Experimental results have been analyzed with computer simulations.