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.

Determining the cryogenic target parameters with high precision calls for the development of a new direction in the area of target characterization based on microtomography methods of data processing. In this report we present our first results in this area.

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.

An experiment has been performed with the LULI Multi-TeraWatt Laser. The acceleration of electrons injected in a plasma wave generated by the laser wakefield mechanism has been observed with a maximum energy gain of 1.5 MeV. It has been shown that the electrons deflected during the interaction, could scatter on the walls of the experimental chamber, and fake a high-energy signal. A special effort has been given in the electron detection to separate the accelerated electrons signal from the background noise.The experimental results agree with theoretical predictions and numerical simulations when 3D effects on the electron beam are taken into account.

The project ITEP-TWAC (Tera Watt Accumulator) being in progress at ITEP (Moscow) requires He-like ions for non-Liouvillean injection into the storage ring to accumulate ≈2·1013 particles with medium masses up to 59Co25+. Powerful lasers were found to be the best choice for those ions production. This work presents the experimental results of highly charge ion generation in plasmas produced by the second harmonic of Nd-glass laser facility with a total energy E ≤ 50 J and pulse duration of about 2.5 ns at GPI (Moscow). Ti and Ta targets were under investigation. An electrostatic ion energy analyzer and an ion charge collector were used to measure the ion charge state spectra at a 3-m distance from the targets. 5·107 He-like Ti ions per cm2 within 1 μs pulse as well as 107 Ta+41 per cm2 within 0.8 μs were observed.

This paper presents comprehensive experimental results of angular distributions of ions emitted from laser-produced plasmas. Performing a series of laser shots onto planar Sn, Au, and Pb targets, both the focusing conditions as well as the tilt angle of the target were changed to study the effect on the plasma expansion. In the experiments, the iodine laser system PERUN (laser energy of 30 J in 350 ps of duration) with laser power density of 5 × 1014 W/cm2 was used. For plasma diagnostics four ion collectors and an ion-energy analyzer were applied. Comparison of angular distribution of the fast ion group (velocity within the range of 1–3.4 × 108 cm/s) and of the slow ion group (velocity within the range of 0.14–1 × 108 cm/s) shows distinct differences. The preferred direction of ion emission of these groups depends seriously on focusing conditions. When setting the focus on the in-focus position both groups of ions are peaked in the direction close to the target normal. The maximum charge of ions registered by the ion-energy analyzer were 36+, 51+, and 49+ for Sn, Au, and Pb, respectively.

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 results of numerical simulation of the neutron generation process in the cone lead targets exposed to laser irradiation are presented. The experimental time dependence of the target shell is used as a boundary condition for the hydrodynamic equations. Deuterium compression is calculated on the assumption that some part of the shell that continues to move inward onto the conical target is decelerated by deuterium in the absence of the reactive force. The behavior of deuterium is described by the 2D equations of two temperature gas dynamics with the electron and ion contributions to the heat conduction taken into account. The behavior of lead is described by the 2D equations of gas dynamics closed by the real wide range equation of state (EOS). The neutron yield in the experiments under discussion is caused by short duration steep rises of the ion temperature generated by the collapse of the heading shock wave and the first reflected one. The stage of adiabatic compression of the high-temperature plasma was lacking in the experiment due to the small mass of the shell.

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.

Two series of experiments on laser irradiation of the different thickness Al-foils were made using laser facilities “GARPUN” and “PICO” (Lebedev Physical Institute, Moscow). “GARPUN” is the KrF-laser with pulse energy Elas ≈ 100 J and pulse duration τ ≈ 100 ns. “PICO” is a Nd-laser facility. The laser energy is Elas1 ≈ 20 J and τ ≈ 3–4 ns in a single beam. The burn through time (tb) of different thickness foils was studied. We have varied the foil thickness: d = 20–500 μm for “GARPUN” facility experiments, and d = 3–12 μm for the case of “PICO” experiments. It was discovered that the rates of the foil burn through are much higher than those obtained in (Dahmani et al., 1991a,b). The experimental data were analyzed with the help of 2D numerical simulations, using the 2D Euler code “NUTCY.” Good agreement was obtained between numerical and experimental results. In the first case the rate of foil “enlightment” is defined by transversal displacement of matter (“drilling effect”). With allowance for the effect of “hot spots formations” it was possible to explain the burn through of thick foils and low laser energy at the rear side of films in “PICO” facility experiments (“microdrilling effect”). The methods of the diminishing of the influence of microdrilling effect (or “imprint” effect) on the nonuniformity of ablation pressure are discussed.

We present results of studies of the behavior of a laser-produced plasma in a strong external transverse magnetic field of above 10 T in induction generated from a flat teflon target at the laser power densities of about 1014 W/cm2. In the measurements of plasma parameters, a two-channel automated interferometric system (Pisarczyk et al. 1994) was applied. The interferometric measurements have shown that the transverse magnetic field induces an asymmetry of the plasma distinctly apparent in the interferograms registered in two mutually perpendicular directions. Due to the lack of axial symmetry of the plasma, the Abel's transformation could not be applied in quantitative processing of the interferograms. To reconstruct a spatial distribution of electron density in a plasma stream of disturbed axial symmetry, a methodology prepared for this experiment was used. Analyzing the spatial and temporal distributions of electron concentration obtained in the transverse magnetic field, it has been proved that the factor responsible for the disturbance of the axial symmetry of the plasma is the Rayleigh–Taylor (R–T) instability corresponding to the ion unmagnetization state.

We studied the influence of foams on laser produced shocks. Experiments were performed at LULI using a Nd laser converted to second harmonic, and at MPQ (Max Planck Institut für Quantenoptik) using the iodine Asterix laser converted to third harmonic. In both cases, sub-ns lasers with pulse energies of several tens of joules were focused on large focal spots (hundreds of microns) to reduce 2D effects. The laser beams were optically smoothed with phase zone plates (PZP) and directly focused on layered targets made of a foam layer on the laser side and a stepped Al layer on the other side. A visible streak camera was used to detect shock breakthrough at the base and at the step of the Al target, allowing shock velocity to be determined. Using the well known SESAME Al equation of state, we determined shock pressure. A stronger pressure increase was measured when foam was present, compared to what was obtained by focusing the laser beam directly on the Al target. This was due to the impedance mismatch effect at the Al-foam interface.

Laser prepulse effect on thermal smoothing of non-uniformities of target illumination is studied by means of 2D Lagrangian hydrodynamics simulation, based on parameters of real experiment. A substantial smoothing effect is demonstrated in case of an optimum delay between the prepulse and main heating laser pulse. The cause of enhancement of thermal smoothing effect by laser prepulse is the formation of long hot layer between the region of laser absorption and ablation surface. Comparison with experimental results is presented.

This work reports on investigations of parameters of ion streams emitted from a plasma produced with a picosecond laser at the power densities ≥1016 W/cm2. Not many papers dealing with such investigations have been published up to now, in spite of the fact that the application of precise corpuscular diagnostics enables better learning of the physical properties of such a plasma. As a result of the investigations carried out, the average and maximum energies of Cu ions were 30 keV and 150 keV, respectively. The maximum charge of Cu ions was 13+. The dependencies of parameters of ions emitted from the plasma on the laser-pulse energy as well as on the location of the focus of the laser beam with respect to the target's surface were also found out. The results obtained from the ion measurements in relation to the results of measurements of X ray are discussed.

We present the results of the experimental testing of the laser facility LAMBDA, created and built at the Institute of Experimental Physics of the Russian Federal Nuclear Center for generation of quasi-steady-state laser fields in microvolumes.

The facility includes: a single mode generator of reference radiation (RR) producing about 10 mJ energy in a pulse of controlled length from 3 to 30 ns; a target chamber with an input objective focusing the RR beam to a micron-size spot, and a 280-mm-diameter parabolic mirror with the focal length also of 270 mm; a two-stage iodine amplifier with the small signal gain coefficient 3·105 per one pass, to the input of which radiation from the target chamber formed by the (microobjective + parabolic mirror) system is applied; a phase conjugating device with the system for the selection of the phase-conjugated component, which allows us to realize the pulse compression in the amplifier stages, and to provide the compensation of the optical aberrations after the second pass amplification and focusing of high-power radiation into the microvolume; a complex for diagnostics of plasma and laser radiation parameters.

The paper presents results of investigations of the process of the creation of a diamagnetic cavity by a laser-produced plasma in a strong transverse magnetic field of 10 T in induction. The plasma was produced from a flat, teflon target by an Nd laser of 5 J in energy and about 1 ns in pulse duration. The investigations were carried on by means of a three-frame interferometry and a non-contact magnetic probe, a so called remote magnetic probe (RMP). For the needs of this work, we developed a methodology for the measurement of the dimensions of the cavity during its expansion by means of the RMP, taking into account the plasma expansion geometry that is specific to flat targets. The dynamics of the process of creation of the diamagnetic cavity, its shape and dimensions have been determined. A very good consistency of dimensions of the diamagnetic cavity and plasma boundary in their quasisteady state, obtained with both diagnostics, allows us to apply the RMP method not only for the investigation of diamagnetic properties of various laser-produced plasmas, but also for the evaluation of their initial kinetic energy and its transformation in magnetic field.

The properties of optical parametric amplifiers are well suited to their use as chirped pulse amplifiers in short pulse high-power systems. In addition to the possibility of very simple designs to extend to shorter pulses the limits of millijoule systems, they can be used for very high-intensity applications when used in conjunction with narrow-bandwidth high-energy lasers. Powers exceeding 10 PW and focused intensities more than 1023 W/cm2 are predicted using existing glass laser technology.

The technique of Chirped Pulse Amplification (CPA) developed by Strickland and Mourou (1985) is now in common use on many laser systems [see, for instance, the review by Perry & Mourou (1994)] and has resulted in massive increases in focused intensities. This paper describes CPA implementation on the Vulcan laser system which has generated multi-Joule sub-picosecond pulses whilst maintaining beam quality to produce focused intensities of 5 × 1019 Wcm−2.

The Petawatt laser at Lawrence Livermore National Laboratory (LLNL) has opened a new regime of laser matter interactions in which the quiver motion of plasma electrons is fully relativistic with energies extending well above the threshold for nuclear processes. In addition to ∼few MeV ponderomotive electrons produced in ultra intense laser-solid interactions, we have found a high energy component of electrons extending to ∼100 MeV apparently from relativistic selffocusing and plasma acceleration in the underdense preformed plasma. The generation of hard bremsstrahlung, photonuclear reactions, and preliminary evidence for positron-electron pair production will be discussed.

When a high power laser (1012 W/cm2) irradiates a target, it induces a shock wave, which reaches the (free) rear surface. The free surface is accelerated and the shock wave is back-reflected as a rarefaction wave. In the shock wave pressure regime involved here, melting of the target during the shock or during the rarefaction may occur. An optically recording velocity interferometric system (ORVIS) has been developed to measure the time evolution of the change in the reflectivity of the free surface. Shock waves of the order of hundreds of kilobars are produced in 50–125 μm thick Sn and Al foils, by a Nd:YAG laser system with a wavelength of 1.06 μm, pulse width of 7 ns (FWHM), and irradiance in the range (1.4–2.4)·1013 W/cm2. The changes in the reflectivity occur along two time scales: a slow one, more than 17 ns in Al and more than 30 ns in Sn, and a rapid one, less than 2.5 ns, in both materials. A possible explanation for the sharp decreases in the time scale is that melting occurs during the release of the free surface.