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.

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.

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.

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 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.

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.

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.

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.

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.

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.

The paper presents an investigation on self-focusing of cosh-Gaussian (ChG) laser beam in a relativistic–ponderomotive non-uniform plasma. It is observed numerically that the selection of decentered parameter and initial beam radius determines the focusing/defocusing of ChG laser beam. For given value of these parameters, the plasma density ramp of suitable length can avoid defocusing and enhance focusing effect significantly. Focusing length and extent of focusing may also be controlled by varying slope of the ramp density. A comparison with Gaussian beam has also been attempted for optimized set of parameters. The results establish that ChG beam focuses earlier and sharper relative to Gaussian beam. We have setup the non-linear differential equation for the beam width parameter using Wentzel–Kramers–Brillouin and paraxial ray approximation and solved it numerically using Runge–Kutta method.

In the Ampfion diode, an ion beam is extracted from an anode plasma that is being pushed away from the cathode by a rising magnetic field. There is concern that ion heating in the anode plasma sheath may result in a significant ion beam divergence. To investigate this possibility, a comparison of Z pinches, θ pinches, and Ampfion is made. Ampfion sheath scenarios are examined and a simple argument is presented that indicates that an anomalous resistivity should develop. An upper bound estimate of the ion divergence is calculated, and examples are given for PBFA-II parameters. For a small radius diode with a high density anode plasma, it is shown that ion beam divergence due to plasma heating should not be a problem. For a large radius diode with a low density anode plasma, it is shown that ion beam divergence due to plasma heating is a problem, but that an Ampfion filtering mechanism should select a cool portion of the heated ions and help to alleviate this problem.

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

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.

Short-pulse, ultrahigh-intensity lasers have opened new regimes for studying fusion plasmas and creating novel ultrashort ion beams and neutron sources. Diagnosing the plasma in these experiments is important for optimizing the fusion yield but difficult due to the picosecond time scales, 10 s of micron-cubed volumes, and high densities. We propose to use the yields of photons and neutrons produced by parallel reactions involving the same reactants to diagnose the plasma conditions and predict the yields of specific reactions of interest. In this work, we focus on verifying the yield of the high-interest aneutronic proton-boron fusion reaction ${}^{11}B{\left(p,2\alpha \right)}^{4}He$, which is difficult to measure directly due to the short stopping range of the produced αs in most materials. We identify promising photon-producing reactions for this purpose and compute the ratios of the photon yield to the α yield as a function of plasma parameters. In beam-fusion experiments, the 11C yield is an easily-measurable observable to verify the α yield. In light of our results, improving and extending measurements of the cross-sections for these parallel reactions are important steps to gain greater control over these laser-driven fusion plasmas.

We describe a direct model for simulation of relativistic electrons acceleration with a given electromagnetic field which is determined by wave packet parameters. The multimode time-spatial structure of a focused Nd-laser beam with stochastic phase disturbances of each spectral component is taken into account as a source of random forces. Electron energies of more than 10 MeV are obtained even at moderate flux densities of 1016 W/cm2. The developed numerical code makes it possible to obtain a quantitative energy distribution function in relation to both field intensity and the temporal bell-shape of the laser pulse. The efficient heating of electrons can be triggered in the presence of a counter propagating wave being reflected from the critical plasma area with a different reflection coefficient. The heating mechanism occurs with a delay relative to the beginning of the pulse when the laser fields exceed some threshold amplitudes. The qualitative comparison of simulation results with the experimental data is given as evidence that this mechanism is reasonable.

We study the problem of the radiation pressure acceleration of ions and the formation of plasma jets, driven by a high-intensity circularly polarized laser beam normally incident on thin plasma targets. We use an Eulerian Vlasov code to solve the one-dimensional relativistic Vlasov-Maxwell equations for both electrons and ions. We consider the case of a high density plasma with n/ncr = 100, where ncr is the critical density. Three cases are studied with different target thicknesses, to investigate the physical processes involved when decreasing the target thickness from several electron skin depths down to the order of one skin depth. The results show a more important acceleration of the ions when the thickness is decreased. Although we observe in all cases a neutral plasma jet ejected from the back of the target, the evolution of the system which leads to the formation of this neutral plasma jet is different in the three cases considered. In each case, this evolution will be studied in details. Also, a leak or ejection of electrons from the back of the target is observed in the thinnest case treated (thickness of the order of the skin depth), before the formation of the neutral plasma jet, a regime called leaky light sail radiation pressure acceleration. The absence of noise in the Eulerian Vlasov code allows an accurate representation of the phase-space structures of the distribution functions.

We present the results of X-ray diagnostics of Z-pinch hot points, formed during fast electrical discharges through exploding Al wires. Experimental data include the pinhole images and X-ray time integrated radiation spectra. These spectra were obtained with high spectral resolution in the range 1.5–2.2 keV, contained the most intensive resonance lines of Al H- and He-like ions. Comparison of the recorded lines width and peak intensities with the corresponding modeled values, enables us to estimate the main hydrodynamical parameters of hot point, such as average temperature and density, being achieved at a moment of its maximum compression. Additionally, on the base of theoretical analysis of the spectral intensities distribution in well-resolved Lyα satellites, the gradient of compression velocities field is concluded. Some features of the investigated lines spectra forming are discussed.

A new and simple type of self-magnetically insulated, vacuum ion diode named “Plasma Focus Diode” has been successfully developed with a large solid angle of irradiation and low divergence angle. The diode has a pair of coaxial cylindrical electrodes similar to a Mather-type plasma focus device. Ion-current density of 1·9 kA/cm2 has been obtained on the anode surface under the experimental conditions of diode voltage ∼1·4 MV, diode current ∼180 kA, and pulse width ∼75 ns. The generated ion beam has been two-dimensionally focused (line focusing) with a focusing radius of ∼0·18 mm, giving a maximum ion current density and beam power density at the axis of ∼0·14 MA/cm2 and ∼0·18 TW/cm2, respectively. The motion of electrons in the gap has been numerically simulated by use of a newly developed particle-in-cell computer simulation code, and good agreement has been obtained between the simulation and the experiment.