A study of angular distribution of X-ray line radiation emitted from a laser-produced plasma is presented. Plasma was produced by irradiating a planar magnesium target using single laser pulses of 6 J, 4.5 ns (FWHM) from an Nd:glass laser system. Angular distribution of X-ray emission in the spectral range of 7–10 Å was recorded using a single X-ray crystal spectrograph. X-ray emission intensity for different resonance lines is observed to decrease up to an angle of ∼45° with respect to target normal, followed by a significant increase at higher angles. The observed departure of angular distribution from a monotonically decreasing behavior is broadly in agreement with the calculations of the escape factor of the radiation at different angles from a thick disk-shaped plasma using a spectroscopic code RATION.

New improvements in the atomic physics models for numerically treating high density plasmas, typical of ICF, together with new algorithms for multigroup radiation transport are presented.

The performance of Large High Aspect Ratio Targets has been numerically determined by using those models implemented in a one-dimensional hydro code. Some differences from experiments are identified, and a comparative analysis with other numerical codes is given.

The interaction of ultrashort laser pulses with a fully ionized plasma is investigated in the plane geometry by means of numerical simulation. The impact of the space oscillations in the amplitude of the laser electric field on the shape of the electron distribution function, on laser beam absorption, and on electron heat transport is demonstrated. Oscillations in the absorption rate of laser radiation with the minima coincident to the maxima of the laser electric field lead to a further decrease in the absorption of laser radiation. Heat flux in the direction of increasing temperature in the underdense region is caused by the modification of the electron distribution function and by the density gradient. A limitation of heat flux to the overdense plasma isobserved with the flux limiter in range 0.03–0.08, growing moderately with the intensity 1014–1016 W/cm2 of the incident 1.2-ps laser pulse.

The Laboratory Microfusion Facility (LMF) has been proposed to study Inertial Confinement Fusion (ICF) targets with reactor-grade gains. An advanced solid-state laser is the prime candidate as the driver for the LMF. However, here we present a conceptual design for an alternate approach using a Nuclear Pumped Laser (NPL).

A pulsed fission reactor is used to excite an oxygen-iodine laser in this design, based on preliminary data on nuclear pumping of O2(1δ). Although a working NPL of this specific type has not yet been assembled, we believe this concept holds great potential, both as a test facility driver and as a future power reactor.

Focusing of heavy-ion beams is an important issue for ion beam-driven inertial confinement fusion. For the experimental program to investigate matter at high energy densities at GSI, the application of a plasma lens has attractive features compared to standard quadrupole lenses. A plasma lens using a wall-stabilized discharge has been systematically investigated and optimized for this purpose. Different lenses were tested in several runs at the GSI linear accelerator UNILAC and at the SIS-synchrotron. A remarkably high accuracy and reproducibility of the focusing were found. The focal spot size was mainly limited by the beam emittance. A summary of experimental results and important limitations of the focal spot size is given.

Two concepts have been applied to the classical problem of accelerators for the ignition of indirectly driven inertial fusion. The first is the use of non-Liouvillian stacking based on photoionisation of a singly charged ion beam. A special FEL appears the most suited device to generate the appropriate light beam intensity at the required wavelength. The second is based on the use of a large number of (>1000) beamlets–or “beam straws”–all focussed by an appropriate magnetic structure and concentrated on the same spot on the pellet. The use of a large number of beams–each with a relatively low-current density–elegantly circumvents the problems of space charge, making use of the non-Liouvillian nature of the stopping power of the material of the pellet. The present conceptual design is based on a low-current (〈i〉 ≈ 50 mA) heavy-ion beam accelerated with a standard LINAC structure and accumulated in a stack of rings with the help of photoionisation. Beams are then extracted simultaneously from all the rings and further subdivided with the help of a switchyard of alternate paths separating and synchronising the many bunches from each ring before they hit the pellet. Single beam straws carry a reasonable number of ions: Beams and technology are directly relatable to the ones presently employed, for instance, at the CERN-PS. Space-charge-dominated conditions arise only during the last few turns before extraction and in the beam transport channel to the reaction chamber. In a practical example, we aim at a peak power of 500 TW delivered to the pellet for a duration of 10–15 ns. High-energy (10 GeV) beam straws of Ba doubly ionised ions are concentrated on several (four) focal spots of a radius of about 1 mm. The power density deposited on these tiny cylindrical absorbers inside a hermetic “hohlraum” is about 2.5 × 1016 w/g. These conditions are believed to be optimal for X-ray conversion, i.e., with an estimated conversion efficiency of about 90%.

The absolutely calibrated K-shell spectra emitted from short-living aluminum plasmas at laser intensities of 5 × 1015–4 × 1018 W/cm2 are reported. The experiments performed with the constant energy, variable-length laser pulses (1.5 ps–1 ns) are modeled by the one-dimensional (1D) hydrodynamics code, including nonlinear resonance absorption of the laser radiation, fast electron acceleration, and energy transfer into the target. The characteristic features of the measured and the postprocessed spectra are outlined. The spatial and temporal profiles of the emitted spectra are presented; the scaling rules for the conversion efficiency of the laser radiation into the line X-ray emission are discussed.

The possibility of using the analytical wave functions in hydrogen-like and semiclassical approximations for self-consistent Hartree-Fock-Slater model is considered. The usage of analytical wave functions simplifies the obtaining of self-consistent field and yields the suitable expressions for calculation various characteristics of high-temperature plasmas—cross sections of radiative processes, Rosseland mean opacities, and equation of state.

Improved measurements of ion-correlation effects in a dense shock-compressed plasma are presented. The extended X-ray-absorption fine-structure (EXAFS) technique on the aluminum K edge is used to observe the short-range order within a dense plasma. Densities of about three times solid density were measured with good accuracy. The experimental measurements of density give results that are in good agreement with the MEDUSA onedimensional fluid code predictions. The improved quality of the data enabled us to calculate the ion coupling parameter during the compression and the subsequent heating of the plasma. An estimation of the temperature is given on the basis of published models, and an approximate agreement is obtained with the MEDUSA code predictions.

This paper summarizes experimental results on the injection and transport of intense, wide cross-section H+ plasma (PB), and ion beams (IB), in vacuum and ambient H+ plasma across an applied B-field. The injection of plasma and ion beams into magnetic confinement devices have the potential to heat and support current in these systems (e.g., field-reversed configurations). The translational energies of the PB and IB ranged between Epb = 60 to 120 eV and EIB = 60 to 120 keV, with temperatures and densities in the range of Tb ∼ 2 to 10 eV, nb ∼ 1012 to 1013 cm−3, and Tb ∼ 200 eV, nb 1010 to 1011 cm−3, respectively. Compared to earlier studies (Peter et al., 1979; Wessel et al., 1988, 1990), this research extends the experimental parameter space to higher beam current densities (up to 30 A/cm2) and higher B-field strengths up to 1.6 kG. The PB and IB were both about 10 cm in diameter at the injection port, and the ratio of beam specific energy to ambient B-field specific energy, β, was in the range of 0.1 to 10. Ratios of beam Larmor radius to beam size, ρ, ranged from 10−1 to 1 and 1 to 10 for the PB and IB, respectively. Cross B-field propagation of the PB in vacuum was undeflected as a whole with a sharp increase (one order or more) in the current density of the central beam core at B-field levels > 1 kG accompanied by a significant loss of beam peripheral layers, beam “braking” and preferential beam expansion along the B-field lines. Cross B-field propagation of the PB in ambient plasma did not differ substantially from the case without B-field, that is, no deflection of the PB as a whole, which could be due to an insufficient neutralization of the induced E-field inside the PB. Cross B-field propagation of the IB in ambient plasma followed a single particle trajectory deflection with a simultaneous significant loss of IB intensity without any detectable bunching, indicating an adequate shorting of the polarization E-field inside the IB.

Optical Thomson scattering has been implemented as a diagnostic of laser ablated plumes generated with second harmonic Nd:YAG laser radiation at 532 nm. Thomson scattering data with both spatial and temporal resolution has been collected, giving both electron density, and temperature distributions within the plume as a function of time. Although the spatial profiles do not match very well for simple models assuming either isothermal or isentropic expansion, consideration of the measured ablated mass indicates an isothermal expansion fits better than an isentropic expansion and indeed, at late time, the spatial profile of temperature is almost consistent with an isothermal approximation.

In this paper we introduce designs that provide short duration megajoule pulses of ¼ micron wavelength light at efficiencies near ten percent.

This paper provides a summary of recent research connected with the shock ignition (SI) concept of the inertial confinement fusion which was carried out at PALS. In the experiments, Cu planar targets coated with a thin CH layer were used. Two-beam irradiation experiment was applied to investigate the effect of preliminary produced plasma to shock-wave generation. The 1ω or 3ω main beam with a high intensity >1015 W/cm2 generates shock wave, while the other 1ω beam with the intensity below 1014 W/cm2 creates CH pre-plasma simulating the pre-compressed plasma related to SI. Influence of laser wavelength on absorbed energy transfer to shock wave was studied by means of femtosecond interferometry and measuring the crater volume. To characterize the hot electron and ion emission, two-dimensional (2D) Kα-imaging of Cu plasma and grid collector measurements were used. In single 1ω beam experiments energy transport by fast electrons produced by resonant absorption made a significant contribution to shock-wave pressure. However, two-beam experiments with 1ω main beam show that the pre-plasma is strongly degrading the scalelength which leads to decreasing the fast electron energy contribution to shock pressure. In both the single 3ω beam experiments and the two-beam experiments with the 3ω main beam, do not show any clear influence of fast electron transport on shock-wave pressure. The non-monotonic behavior of the scalelength at changing the laser beam focal radius in both presence and absence of pre-plasma reflects the competition of plasma motion and electron heat conduction under the conditions of one-dimensional and 2D plasma expansion at large and small focal radii, respectively.

A current flowing between the ground and target exposed to the nanosecond laser radiation is analyzed to complete characteristics of laser ablation. Three phases of the target current are distinguished. During the ignition phase, the electron emission is driven by the laser pulse and the positive charge generated on the target is balanced by electrons coming from the ground through the target holder. At post-pulse times, a peaked waveform of the target current is typical for the active phase of the plasma and can give information on the material composition of the ablated surface layers. The afterglow phase is determined by a current of electrons flowing from the target to the ground. Experiment shows that the time-resolved target current is very sensitive to the actual composition of the surface layer of irradiated target and laser parameters.

Recent progress in laser-plasma accelerators has matured a concept of particle acceleration as a possible next-generation particle accelerator promising ultrahigh accelerating gradients in a compact size. Four major concepts of laser-plasma accelerators—the plasma beat wave accelerator, the laser wakefield accelerator, the self-modulated laser wakefield accelerator, and the plasma wakefield accelerator—are reviewed on accelerator physics issues and experiments demonstrating the basic mechanisms of their concepts. As a perspective to the future practical application, a design of 5-TeV linear colliders based on the laser wakefield accelerator is discussed.

Spectral-luminescent properties of the Nd3+-activated laser liquid based upon POCl3-SnCI4 upon excitation by-products of nuclear reactions have been researched. It was concluded that the main luminescence characteristics such as T, Δλ, and λmax depend slightly upon the way of the medium excitation. It was obtained that the pumping efficiency δ of the upper working level is directly proportional to the activator ions' concentration and almost independent of the uranyl presence in the liquid. The measured values t, Δλ, λmax, and δ were used for the estimates of some parameters of nuclear-pumped lasers based upon phosphorus oxychloride. The effect of the Nd3+ ions laser action from the 4F3/2 level to the 4I11/2 level (λ = 1,050 nm) in aprotic liquids POCI3-SnCl4 in the presence of uranium by flashlamp pumping has been obtained.

This paper gives out two kinds of novel well-behaved stimulated Brillouin scattering (SBS) mediums, FC-3283 and FC-770. Numerical calculation and experimental measurements show these two mediums both having lower absorption, higher optical loads and short phonon lifetime, which making them good candidate mediums for high-energy high-power SBS. Using them as the mediums in the compacted two-cell SBS phase-conjugation mirror, it is easily to generate ultrashort phased-conjugated Stokes pulses just with hundreds picoseconds. When the incident light energy is beyond 200 mJ, the pulse width of 8 ns can be compressed to 200 ps or less in both mediums. Especially, the FC-770 is very suitable to be chosen for generating the SBS picosecond pulses with the narrowest compression pulse width of 109 ps and the highest energy reflectivity of 80%.

This paper aims at a test of a plasma focus (PF) device as a metallic plasma jet generator. The experiment was carried out at the DPF-1000U device in which the inner electrode face was conically shaped. Deuterium (D2) with the initial pressure of 0.9 Torr was used as a filling gas. In the experiment, a metallic plasma was ensured due to erosion of the inner electrode during a PF discharge. To create the metallic plasma jet, the eroded copper (Cu) plasma, swept by the deuterium plasma sheath, was accelerated axially and compressed to very small radius (about 1–2 mm). The Cu plasma jet achieved a velocity of 3 × 107 cm/s. To study processes of the plasma jet creation and propagation a 16-frame laser interferometer and a four-frame X-ray pinhole camera were used. Recorded images prove a successful adaptation of the PF device to the metallic plasma jet generator.

The luminescence spectra of noble gases and their binary mixtures were measured using heavy ion beam excitation from a DC-60 accelerator. Spectra were measured in the range of 200–975 nm; the gas spectra were dominated by lines of p–s and d–p atomic transitions; in neon and argon, lines from atomic oxygen, N2, N2 +, and OH radical bands were also observed. The ultraviolet region of the spectra was represented by a “third continuum” of noble gases. In krypton, the band of the KrO excimer molecule with a maximum at 557 nm was also observed. The maxima of the heteronuclear ionic molecules bands were located at wavelengths of 329 and 506 nm (Ar–Xe), 491 nm (Kr–Xe), and 642 nm (Ar–Kr). The relative intensities of the 2p–1s transitions of the noble gases atoms were measured and are discussed.

A 3D verification and validation suite of test problems is presented and used to evaluate hydrodynamic methods within a radiation hydrodynamics code, xRAGE. These test problems exercise different levels of complexity, building towards ICF problems which in addition to hydrodynamics also include three temperature plasma physics, thermal conduction, and radiation diffusion. Among the problems in the test suite are the Kidder ball problem, the Verney shell problem, and a 5-material compression problem, which exercise different purely hydrodynamic methods implemented within xRAGE. There is excellent agreement between 2D and 3D XRAGE simulation results and between the xRAGE results and the benchmark solutions. Two 3D ICF test problems are also presented, based on an OMEGA direct drive capsule experiment and on a NIF indirect drive capsule experiment. It is demonstrated that the newer unsplit hydrodynamic method in xRAGE produces more vorticity relative to the older default method. For the indirect drive capsule, the 3D simulations are in reasonable agreement with the experimental values of ion temperature and neutron production.