The paper presents results of two-dimensional particle-in-cell simulations of ion beam acceleration at the interactions of a 130-fs laser pulse of intensity in the range 1021–1023 W/cm2, predicted for the Extreme Light Infrastructure lasers, with thin hydrocarbon (CH) or erbium hydride (ErH3) targets. A special attention is paid to the effect of the laser pulse intensity and polarization (linear, circular) on the proton energy spectrum, the proton beam spatial distribution and the proton pulse shape and intensity. It is shown that for the low laser intensities (~1021 W/cm2) considerably higher proton beam parameters (proton energies, beam intensities) are achieved for the ErH3 target for both polarizations and the effect of polarization on the beam parameters is significant (higher parameters are achieved for the linear polarization). However, for the highest, ultra-relativistic intensities (~1023 W/cm2) higher proton beam parameters are attained for the CH target and the effect of polarization on these parameters is relatively low. In this case, for both polarizations quasi-monoenergetic proton beams are generated from the CH target of the mean proton energy ~2 GeV and $dE_{\rm p} /\bar E_{\rm p} \approx 0.3$ for the linear polarization and $dE_{\rm p} /\bar E_{\rm p} \approx 0.2$ for the circular one. At the highest laser intensities also the proton pulse peak intensities are higher for the CH target and for both polarizations they reach values well above 1021 W/cm2. In the paper, the properties of proton beam generation indicated above are discussed in detail and a physical explanation of the observed effects is done.

The measured spatial-intensity distribution of the beam of protons accelerated from the rear side of a solid target irradiated by an intense (>1019 Wcm−2) laser pulse provides a diagnostic of the two-dimensional fast electron density profile at the target rear surface and thus the fast electron beam transport pattern within the target. An analytical model is developed, accounting for rear-surface fast electron sheath dynamics, ionization and projection of the resulting beam of protons. The sensitivity of the spatial-intensity distribution of the proton beam to the fast electron density distribution is investigated. An annular fast electron beam transport pattern with filamentary structure is inferred for the case of a thick diamond target irradiated at a peak laser intensity of 6 × 1019 Wcm−2.

Lower hybrid wave excitation in magnetized plasma by an ion beam via Cerenkov interaction is studied. The lower hybrid modes showed maximum growth rate of the instability when phase velocity of the lower hybrid mode along the magnetic field is comparable to the electron thermal velocity. We have derived the expression for the maximum growth rate and found that the growth rate of the instability increases with beam density. Moreover, the maximum growth rate of the instability scales as the one-third power of the beam density. The real part of the frequency of the unstable wave increases as almost the square root of the beam energy.

We apply the average electron model to describe high harmonic generation in a collisional plasma in a laser field. The model is based on the coupled kinetic equations for electron velocity and electron temperature. The harmonic intensities are obtained from the Fourier coefficients of the nonlinear part of the electron velocity. Numerical calculations are reported for both strongly and weakly ionized plasmas in the nonstationary regime. We show the role of collisions frequencies as well as of quiver and thermal velocities in the harmonic generation efficiency.

Three-dimensional plasma simulations of interacting galactic-dimensioned current filaments show bursts of synchroton radiation of energy density 1·2 ×10−13 erg/cm3 which can be compared with the measured cosmic microwave background energy density of 1·5 × 10−13 erg/cm3. However, the synchrotron emission observed in the simulations is not blackbody. In this paper, we analyze the absorption of the synchrotron emission by the current filaments themselves (i.e., self-absorption) in order to investigate the thermalization of the emitted radiation. It is found that a large number of current filaments (>1031) are needed to make the radiation spectrum blackbody up to the observed measured frequency of 100 GHz. The radiation spectrum and the required number of current filaments is a strong function of the axial magnetic field in the filaments.

It is important to ameliorate the early time imprinting of nonuniformities due to laser radiation or target shell surface in an inertial confinement fusion (ICF) scheme. However, they will not prevent the instabilities which originate at the ablation surface due to acceleration of high density plasma by low density plasma. One of the methods discussed here is to combat the growth of instabilities at the ablation surface. The present work is aimed to control growth of hydrodynamic instability in laser irradiated target at moderate intensities. Laser (λ = 1.06 μm) radiation was focused on the plastic (base) target seeded with microinclusions of Al and Au at various concentrations. Targets had planar geometry and were of few microns in thickness. The target stability was studied using the optical backlighting technique. Shadowgrams of the seeded targets show a uniform motion of the target rear, whereas pure plastic targets break up under identical conditions. Results are analyzed by considering the X-radiation transport, coherent structure effects of the plasma like vortices, self-generated magnetic field in the accelerated target, and nonlinear conversion of long wavelength perturbation into short wavelength perturbation.

The chlorine Heα radiation of polyvinyl chloride (PVC) was investigated with respect to X-ray scattering experiments on dense plasmas. The X-ray source was a laser-produced plasma that was observed with a highly reflective highly oriented pyrolytic graphite (HOPG) crystal spectrometer as it is used in current x-ray scattering experiments on dense plasmas. The underlying dielectronic satellites of Heα cannot be resolved, therefore the plasma was observed at the same time with a focusing spectrometer with spatial resolution. To reconstruct the spectrum a simple model to calculate the spectral line emission based on dielectronic recombination and inner shell excitation of helium- and lithium-like ions was used. The analysis shows that chlorine dielectronic satellite emission is intense compared to Heα in laser-produced chlorine plasmas with a temperature of 300 eV in this wavelength range of Δλ = 0.07 Å (ΔE = 43 eV). The method proposed in this paper allows deducing experimentally the role of the underlying dielectronic satellites in the scatter spectrum measured with a HOPG crystal spectrometer. It is shown that the dielectronic satellites can be neglected when the scattering is measured with low spectral resolution in the non-collective regime. They are of major importance in the collective scatter regime where a high spectral resolution is necessary.

Energy deposition by high-intensity pulsed ion beam into a metal target has been studied with time-of-flight (TOF) of ions which can be related to the original ion kinetic energy E0 and the ion mass with . It is found that the TOF effect has a profound influence on the kinetic energy distribution of implanted ions and subsequent energy deposition process into the target. The HIPIB of mixed H+ and C+ was extracted from a magnetically insulated ion diode at a peak accelerating voltage of 350 kV, leading to an ion current density of 300 A/cm2 at the target. The widespread ion energy spectrum remarkably varied in shape as arriving at the target surface, from the original Gaussian-like of 80-ns duration to a pulse form of a sharp front and a long tail extending to about 140-ns duration. Energy loss of the mixed ions into a Ti target was simulated utilizing a Monte Carlo method. The energy deposition generally showed a shallowing trend and could be divided into two phases proceeded with sequent arrivals of H+ and C+. Note that, the peak value of deposited energy profile appeared at the beginning of mixed ion irradiation phase, other than the phase of firstly arrived H+ with peak kinetic energy and peak ion current. This study indicated that TOF effect of ions greatly affects the HIPIB-matter interaction with a kinetic energy spectrum of impinging ions at the target, noticeably differing from that of original output of the ion source; consequently, the specific energy deposition phenomena of the widespread ion energy can be studied with the TOF correlation of ion energy and ion current, otherwise not obtainable in common cases assuming fixed ion energy distribution in accordance with the original source output.

The results of numerical and experimental studies of high-intensity proton beam generation using a 2ω or 1ω Nd:glass laser beam irradiating a thin hydrogen-rich target are reported. The effect of the laser wavelength (λ), intensity (IL) and pulse duration as well as the target thickness, and the preplasma density gradient scale length on proton beam parameters, and the laser-protons energy conversion efficiency were examined by particle-in-cell simulations. Both the simulations and measurements, performed on the LULI 100 TW laser facility at IL up to 2 × 1019W/cm2, prove that at the ILλ2 product fixed, the 2ω laser driver can produce proton beams of intensity, current density and energy fluence significantly higher than the ones which could be achieved using the 1ω driver. In particular, at ILλ2~(0.5–1) × 1020 Wcm−2 µm2 the 2ω picosecond driver makes it possible to generate multi-MeV proton beams of intensity and current density in excess of 1021W/cm2 and 1014A/cm2, respectively, with the conversion efficiency above 10%.

Analysis is given for nonstationary propagation of rotating ion beam which has a finite length on the basis of Vlasov–Maxwell equations. The beam velocity distribution function is assumed to have a form of product of a modification function g which depends on time and axial coordinate multiplied by a steady solution fb0 which is a known function of particle velocity and radial coordinate. Unknown function g is solved as the solution of Vlasov equation through electromagnetic fields induced by leading and trailing edges. These electromagnetic fields can be solved from the Maxwell equations by using beam distribution function and motion of electrons in background plasma.

In this paper, the intense laser heating of hydrogen pair-ion plasma with and without electron impurities through investigation of related nonlinear phenomena has been studied in detail, using a developed relativistic particle-in-cell simulation code. It is shown that the presence of electron impurities has an essential role in the behavior of nonlinear phenomena contributing to the laser absorption including phase mixing, wave breaking, and stimulated scatterings. The inclusion of electron into an initial pure hydrogen plasma not only causes the occurrence of stimulated scattering considerably but also leads to the faster phase-mixing and wave breaking of the excited electrostatic modes in the system. These nonlinear phenomena increase the laser absorption rate in several orders of magnitude via inclusion of the electrons into a pure hydrogen pair-ion plasma. Moreover, results show that the electrons involved in enough low-density hydrogen pair-ion plasma can be accelerated to the MeV energy range.

The experimental progress of laser equation of state (EOS) studies at Shanghai Institute of Laser Plasma (SILP) is discussed in this paper. With a unique focal system, the uniformity of the laser illumination on the target surface is improved and a laser-driven shock wave with good spatial planarity is obtained. With an inclined aluminum target plane, the stability of shock waves are studied, and the corresponding thickness range of the target of laser-driven shock waves propagating steadily are given. The shock adiabats of Cu, Fe, SiO2 are experimentally measured. The pressure in the material is heightened remarkably with the flyer increasing pressure, and the effect of the increasing pressure is observed. Also, the high-pressure shock wave is produced and recorded in the experimentation of indirect laser-driven shock waves with the hohlraum target.

This article reports the first Richtmyer–Meshkov instability experiments using an improved version of the Atomic Weapons Establishment convergent shock tube. These investigate the shock-induced turbulent mixing across the interfaces of an air/dense gas/air region. Multipoint ignition of a detonatable gas mixture produces a cylindrically convergent shock that travels into a test cell containing the dense gas region. The mixing process is imaged with shadowgraphy. Sample results are presented from an unperturbed experiment and one with a notch perturbation imposed on one of the dense gas interfaces. The unperturbed experiment shows the mixing across the dense gas boundaries and the motion of the bulk dense gas region. Imposition of the notch perturbation produces a mushroom-shaped air void penetrating the dense gas region. Three-dimensional simulations performed using the AWE TURMOIL3D code are presented and compared with the sample experimental results. A very good agreement is demonstrated. Conducting these first turbulent mixing experiments has highlighted a number of areas for future development of the convergent shock-tube facility; these are also presented.

The measurement of charged particles and cavitation bubble expansion velocity is reported in a laser induced breakdown in water using beam deflection set-up. Effect of laser power on charged particles, cavitation bubble velocities and higher order bubble oscillations is also studied.

The competition of stimulated Raman forward scattering and backscattering in a hightemperature, underdense, nearly homogeneous plasma slab is investigated. In such plasmas Landau damping limits the growth of the Raman backscattering, and the weaker forward process may reach comparable levels. A modest seeding of one of the scattered electromagnetic waves influences the competition to a large extent. The conversion of the pump wave to scattered waves is calculated. The simultaneous operation of the two processes can lead to considerable modifications in the electron distribution; e.g., two hot tail components are formed because the plasma waves involved have different phase velocities. The generation regions of the scattering processes are spatially separated. Consequently, a large number of thermal electrons can be accelerated to very high energies in two stages. The backward plasmons preaccelerate the electrons and the faster plasmons, excited in the forward scattering, operate as a booster.

Ray-tracing simulations of an optical X-ray system based on a spherically bent crystal operating in Bragg configuration for monochromatic projection imaging of thin samples are presented, obtained using a code developed for that purpose. The code is particularly suited for characterizing experimental arrangements routinely used with laser-produced plasma X-ray sources. In particular, the spatial resolution of the imaging system was investigated and a careful study of the complex pattern of the X-ray backlighting beam was performed.

An intense and focused heavy ion beam is a suitable tool to generate high energy density in matter. To compare results with simulations it is essential to know beam parameters as intensity, longitudinal, and transversal profile at the focal plane. Since the beam's energy deposition will melt and evaporate even tungsten, non-intercepting diagnostics are required. Therefore a capacitive pickup with high resolution in both time and space was designed, built and tested at the high temperature experimental area at GSI. Additionally a beam induced fluorescence monitor was investigated for the synchrotron's (SIS-18) energy-regime (60–750 AMeV) and successfully tested in a beam-transfer-line.

Multiple-pass amplifiers were configured from Nd:glass rods using polarization and angular coupling techniques. Very high gain (>600) single beam triple-pass booster stages and high gain (30 or 15) single or double-beam double-pass amplifiers were combined to construct a very cost effective high-power (50 GW) pulsed laser system. These techniques were also effectively applied to smaller compact high repetition-rate systems.

Ion acceleration by lasers is one of the most important innovations in laser-plasma research in recent years. A mechanism that has gained great attention due to the remarkable properties of the accelerated beam is laser acceleration of protons from the rear surface of solid targets. A striking prediction is that these protons are capable of generating images of micro-structures present on this surface. These images might be useful to measure properties of the accelerated beam. In this article, we address the physics of the generation of images of surface structures imprinted into the target back surface with laser-accelerated protons.

Resonant absorption of first-overtone (FO) CO laser radiation by atmospheric water vapor and various organic and nonorganic pollutants is discussed. Suitable ro-vibrational lines are selected for their potential use in traditional spectroscopic schemes of atmospheric pollution diagnostics. Nonlinear atmospheric absorption of intense multiline FO CO laser radiation is simulated and laser-induced changes in absorption spectra are demonstrated. Absorption coefficients of a few substances on several FO CO ro-vibrational lines are experimentally measured. A comparative analysis of spectral characteristics of an FO CO laser and an HF (DF) laser demonstrates that the potential of FO CO laser applications for spectroscopic detection of various molecular trace gases is greater than that of HF and DF lasers.