The purpose of the present paper is to describe the effects of electron-electron collisions on proton electronic stopping in plasmas of any degeneracy. Plasma targets are considered fully ionized so electronic stopping is only due to the free electrons. The stopping due to free electrons is obtained from an exact quantum mechanical evaluation in the random phase approximation, which takes into account the degeneracy of the target plasma. The result is compared with common classical and degenerate approximations. Differences are around 30% in some cases which can produce bigger mistakes in further energy deposition and projectile range studies. We focus our analysis on plasmas in the limit of weakly coupled plasmas then electron-electron collisions have to be considered. Differences with the same results without taking into account collisions are more than 50%.

The structure of large clusters such as neutral clusters, metallic clusters, and clusters ion is investigated. Furthermore, the electron distribution of large clusters when they are irradiated by an intense ultrashort laser pulse is treated. The cluster excitation results from the interaction of the electron subsystem with the laser field. Analyzing the quantum metallic cluster proves that its properties differ essentially from the properties of a classical small metallic sphere. The eigen frequency of the surface oscillation of a cluster is obtained and it is shown that it is lower than Mie frequency because of Thomas–Fermi screening.

We present some preliminary results on the equation of state (EOS) of water in a pressure regime of astrophysical interest. In the experiments, structured targets made of an aluminum step followed by a water layer are irradiated by the laser at an intensity up to 4·1014 W·cm−2 to generate a shock wave. Velocities are measured in the two materials using a VISAR interferometric diagnostic for water, and a streak camera to measure target self-emission for Al. EOS points for water are obtained with the impedance mismatch method using Al EOS as a reference. Water reflectivity was also measured.

Highly nonlinear ellipsoid bubble regime of the laser wake-field acceleration with high-intensity laser pulse is considered with analytical and numerical calculations. The important property of this regime is the production of the mono-energetic high-quality electron beam. We introduce a new twofold ellipsoid structure of the bubble (egg shape) by referring to some published two-dimensional (2D) and 3D simulations. In this paper, a new analytical formalism is introduced, in which dimensions of the front part of the ellipsoid bubble are related to the laser pulse and plasma parameters. These relationships are in agreement with 2D particle-in-cell code results in recent work (Benedetti et al., 2013).

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.

This paper presents the results of comprehensive studies of the efficiency of a pulsed electron beam transmission through a mixture of gases: nitrogen (83%), carbon dioxide (14%), and oxygen (2.6%) in the presence of ash and water vapor. The studied concentrations correspond to the concentrations of nitrogen, oxygen, and carbon dioxide in flue gas. The pressure and concentration of water vapor and ash in the drift chamber varied (375, 560, and 750 Torr; humidity 15 ± 5% and 50 ± 15%). The charge dissipation of a pulsed electron beam in the gas mixture in the presence of ash and water vapor was investigated, as well as the effect of the concentration of water vapor and ash on the geometric profile of the pulsed electron beam.

The X-ray spectral distribution of swift heavy Ti and Ni ions (11 MeV/u) observed inside aerogels (ρ = 0.1 g/cm3) and dense solids (quartz, ρ = 2.23 g/cm3) indicates a strong presence of simultaneous 3–5 charge states with one K-hole. We show that the theoretical analysis can be split into two tasks: first, the treatment of complex autoionizing states together with the originating spectral distribution, and, second, a charge-state distribution model. Involving the generalized line profile function theory, we discuss attempts to couple charge-state distributions.

The products of fusion reactions have unique properties which can be used for direct energy conversion. These products are neutrons and ions. Neutrons can be transported very long distances through solid materials and can interact with certain elements which have a very high absorption cross section. Ions on the other hand have a very short transport length even in a gaseous medium. It is possible to utilize these products in an inertial confinement fusion reactor with two different direct energy conversion devices: a nuclear-pumped laser using neutrons from the fusion reaction; a photon generator material combined with a photovoltaic converter using the ionic fusion products.

It will be argued that a nuclear-pumped laser can be more efficient than a conventional laser. It will also be shown that an advanced energy conversion concept based on photon production and photovoltaics can produce ICF system efficiencies of 56%.

The generation of fast ion beams in the hole-boring radiation pressure acceleration by intense laser pulses has been studied for targets with different ion components. We find that the oscillation of the longitudinal electric field for accelerating ions can be effectively suppressed by using a two-ion-species target, because fast ions from a two-ion-species target are distributed into more bunches and each bunch bears less charge. Consequently, the energy spread of ion beams generated in the hole-boring radiation pressure acceleration can be greatly reduced down to 3.7% according to our numerical simulation.

Inertial confinement fusion using light ion beams requires fast rise time, high power drivers. One technique to enhance a conventional pulsed power generator is to use a plasma erosion opening switch (PEOS) between the generator and the ion diode. Ideally, the PEOS conducts current until a current threshold is reached, then rapidly opens and delivers the inductively stored energy to the load on a short time scale. Experiments at the Naval Research Laboratory (NRL) used a PEOS to improve the Gamble II current rise time from 60 ns to 10 ns at 1 MA. Load voltages over 4 MV have been obtained (>2× the matched load voltage).

Based on these experiments and theoretical predictions, a PEOS system has been incorporated into the PBFA II experiment at Sandia National Laboratories (SNL). The PEOS on PBFA II is ultimately to provide a 6 to 8-MA, 30-MV pulse with 10-ns rise time into an “applied B” ion diode. This is a large extrapolation of present experiments. The PEOS system on PBFA II is described here and theoretical predictions are given.

In our earlier papers, we demonstrated that plasma pressure decreases with the growing atomic number of the target material. That experimentally confirmed fact brought about a question whether it would be possible to collimate the Al plasma outflow by using plastic plasma as a compressor. To prove that idea we used in our next experiments a plastic target with an Al cylindrical insert of 400 µm in diameter. The measurements were carried out at the Prague Asterix Laser System iodine laser facility. The laser provided a 250 ps (full width at half maximum (FWHM)) pulse with energy of 130 J at the third harmonic frequency (λ3 = 0.438 µm). The focal spot diameters (ΦL) 800, 1000, and 1200 µm ensured predominance of the plastic plasma amount high enough for the effective Al plasma compression. To study the Al plasma stream propagation and its interaction with plastic plasma a three-frame interferometric system and an X-ray camera were used. The experiment provided a proof that creation of the collimated Al plasma jet by action of outer plastic plasma is feasible. In order to discuss of the experimental results a thorough theoretical analysis was carried out.

Wavelength dependent absorption in laser-plasma interactions was investigated by measuring the energy spectra of freely expanding plasmas in their asymptotic stage of expansion. The experiments were performed with both 1·06- and 0·53-μm-wavelength light incident on flat tantalum targets. The experimental conditions were chosen adequately to ensure that inverse bremsstrahlung was the dominating absorption mechanism. As a result it is found that the absorption is enhanced at the shorter wavelength by a factor of 1·3. Primarily this leads to a higher ionisation state of the plasma and higher kinetic ion energies and temperatures, respectively, while the amount of ablated mass is approximately the same.

The results of 1-D numerical study are reported for a class of simple D-T targets driven by the beams of heavy ions. A simple target is defined as a uniform spherical metallic shell with the frozen D-T deposited on its inner surface and the D-T gas in the central cavity. Optimum target parameters have been found for several combinations of the three relevant driver parameters—the input energy Ein, the beam pulse duration tin, and the beam ion energy Eb. A simple box pulse profile was assumed. As a central set of driver parameters around which most of the calculations have been done, the values Ein = 6.12 MJ, tin = 17 ns, and Eb = 20 GeV have been adopted. It was found that all the targets from the class under consideration ignite uniformly over the entire fuel mass. Maximum energy gains amount to Gopt = 80–100. The physical picture of the target performance is analyzed in detail.

The propagation of a 1-ps laser pulse at intensities exceeding 1019 Wcm−2 in a low-density plasma channel was experimentally tested. The channel was produced by a lower intensity preceding pulse of the same duration. Plasma electrons were accelerated during the propagation of the main pulse, and high energy γ-ray detectors were used to detect their bremsstrahlung emission. The γ-ray yield was studied for different channel conditions, by varying the delay between the channel forming pulse and the high intensity pulse. These results are correlated with the interferograms of the propagation region into the plasma.

From analytic models of the ablation process in laser-plasma experiments, as well as simulations with Fokker–Planck and Spitzer codes, we have identified a new effect, thermal inertia smoothing. This effect results in a smoother Fokker–Planck temporal and spatial variation of the ablation pressure than that for Spitzer, for the same applied timevarying laser intensity. It is therefore advantageous for incoherent optical smoothing schemes. This is especially true at early times in the laser pulse (≤100 ps).

A Genuine two-fluid model of plasmas with collisions permits the calculation of dynamic electric fields and double layers inside plasmas including oscillations and damping. For the first time a macroscopic model for coupling of electromagnetic and Langmuir waves was achieved with realistic damping. Starting points were laser produced plasmas showing very high dynamic electric fields in nonlinear force produced cavitons and inverted layers, in agreement with experiments. Applications for any inhomogeneous plasma as in laboratory or in astrophysical plasmas can then be followed up by a transparent hydrodynamic description. We find the rotation of plasmas in magnetic fields and a new second harmonic resonance. Explanation of inverted double layers, second harmonic emission from laser produced plasmas, and laser acceleration of charged particles by the very high fields of the double layers is given.

X-ray emission from Kr13+ ions in the energy range 1.2–3.6 MeV in steps of 0.6 MeV impacting on an Au target was investigated on electron cyclotron resonance ion source at the Heavy Ion Research Facility in Lanzhou. It was found that a shift of the X-ray lines to the higher energy side occurred. We measured the relationship between the characteristic of X-ray yield of Au M X-rays and Kr L X-rays as a function of incident energy. Furthermore, M-shell X-ray production cross-section of Au induced by Kr13+ was measured. The measured cross-section of target is compared to the classical binary-encounter approximation and plane-wave-born approximation theoretical model, which is a significant different between experimental and theoretical model.

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.

Use is made of the extraordinary-mode eigenvalue equation to investigate detailed properties of the magneteron instability for relativistic nonneutral electron flow in a cylindrical high-voltage diode with cathode located at r = a and the anode located at r = b. The model is based on the cold-fluid-Maxwell equations including the full influence of self-field and cylindrical effects. The equilibrium radial electric field Er (r)êr and axial magnetic field Bz (r)êz induce an azimuthal flow of electrons with angular velocity ωb(r) = Vθb (r)/r. The stability analysis assumes flute perturbations with extraordinary-mode polarization. The equilibrium radial electric field is specified by Er (r) = const, sinh k (r − a) within the electron layer (a ≤ r ≤ rb), and emphasis is placed on calculating equilibrium and stability behavior in a parameter regime characteristic of the PBFA-II diode experiments. In particular, voltages in the range 10 MV to 14·75 MV are considered, assuming a = 12 cm, b = 15 cm, and normalized layer thickness Δb = (rb − a)/(b − a) ranging from Δb = 0·3 to Δb = 0·6. At the high voltages characteristic of PBFA-II operation, a moderately strong applied magnetic field B0 is required to assure magnetic insulation of the layer electrons from the anode. Here, B0 is the magnetic field in the vacuum region rb < r ≤ b. Correspondingly, the value of normalized density is typically small. Here, ωc0 = eB0/mc, and ωp0 is the plasma frequency at the cathode. As a general remark, for fixed values of the geometric factors Δb, b − a, etc., it is found that there is a sensitive dependence of the magnetron instability growth rate on the relativistic flow velocity as measured by , with higher values of γ(rb) favoring stronger growth. Typical maximum growth rates are in the range of a few to several percent of ωc0.

The MAGO concept using the thermonuclear target with DT gas preliminary heating up to kiloelectronvolt range temperatures, which sufficiently enables the reduction of requirements of the compression rate (to 10 km/s) and the compression degree (to several hundreds) of the target, is investigated. The MAGO chamber with the Laval supersonic annular nozzle is used for plasma preheating. In this chamber magnetized plasma is accelerated up to 1000-km/s velocities and heated by collisionless shock waves. Systems with liner and magnetic compression are considered for the subsequent plasma compression. Energizing of a real-size system can be supplied by the magnetic flux compression generators with energy 100−500 MJ. Experiments close to the threshold of ignition can be conducted proportionally in 2−3 times reduced systems. Then the energy required will be 10–30 times less than in a real-size system.