The short review on the possible applications of the hollow ion spectra for the diagnostics of the high-temperature plasma created by intensive laser and particle beams is presented. Because of the hollow ion spectra features are defined mainly by the mechanisms of their excitation, we consider the various types of the high-temperature plasma where different excitation processes are important. It is shown that like ordinary spectral lines, spectra of the hollow ions offer considerable diagnostic opportunities. At the present time, hollow ion spectra are used mainly to investigate plasma heated by X-ray radiation, but the hollow ions must be generated when plasma is heated by fast heavy ion beams too. In this case, the resultant substance state will be also characterized by solid-state density, and some spatial regions of targets will have relatively low temperatures, i.e., will be a nonideal plasma. It is emphasized that hollow ion spectra are promising diagnostic tool for both nonideal plasma and warm dense matter.

The anomalous absorption of laser, incident at an arbitrary angle of incidence on a metal surface embedded with nanoparticles, is studied. The electrons inside a nanoparticle resonantly absorb laser energy when the laser frequency equals the frequency of surface charge oscillations of the nanoparticle. A monolayer of nanoparticles of radius rnp0 ≈ 50 A with inter-particle separation d ~ 10rnp0 can cause up to 40% reduction of the reflection of p-polarized laser light. The absorption coefficient increases with the angle of incidence and has a sharp peak at a resonant frequency width of about 1%. At high laser power, even if the nanoparticles are initially off resonant with the laser, the particle heating and subsequent expansion reduces the resonance frequency, and the resonance absorption is realized after a time delay. The delay is found to be directly proportional to the cluster size and inversely proportional to the laser intensities.

Capsules with a thin aerogel shell were prepared by the OO/W/OI emulsion process. (Phloroglucinol carboxylic acid)/formaldehyde (PF) was used as the water phase (W) solution to form the shell of the capsule. PF is a linear polymer prepared from phloroglucinol carboxylic acid. The viscosity of the PF solution can reach a high level of 9×10−5 m2/s without gelation while resorcinol/formaldehyde (RF) gelates at ~3–4×10−5 m2/s. Using the viscous PF solution, capsule with a 17 µm gel shell was fabricated. This thickness satisfies the specification of the first phase of Fast Ignition Realization Experiment (FIREX-I) at Osaka University. When PF gel was extracted to remove the organic solvent, shrinkage of 9% occurred. The final density of the PF aerogel was 145 mg/cm3. Both the shell thickness and density can satisfy the specification of FIREX-I. The pore size of the PF aerogel was less than 100 nm while that of RF was 200–500 nm. The SEM showed that PF had particle-like foam structure while RF had fibrous-like foam structure.

Since Roentgen's discovery of X rays in the late 1800s the use of penetrating radiation to form images has become a part of our everyday life as well as providing a useful tool for the scientific study of processes that have been previously impossible to measure. This can include the study of processes that are too deeply embedded in opaque materials for direct observation, or that occur on a length or time scale smaller than otherwise can be easily measured. As technologies to generate penetrating radiation and quickly collect images have matured, new techniques have emerged to measure processes that have been hidden for many years. One example is advances in flash radiography using charged particles as radiographic probes, including proton radiography and electron radiography. Recently the successful commissioning of proton microscope systems has provided remarkable improvements in spatial resolution. These techniques are being implemented for applications with electron radiography. With the evolution of these new techniques comes the opportunity to choose the probe that provides the maximum information for the desired measurement. This paper describes these new imaging techniques, predicts the capabilities of high-energy electron radiography, and provides a guide for identifying the optimal probe for a wide range of measurements.

It is shown that the above-threshold electron de Broglie waves, generated by an intense laser pulse at a metal surface are interfering to yield attosecond electron pulses. This interference of the de Broglie waves is an analog on of the superposition of high harmonics generated from rare gas atoms, resulting in trains of attosecond light pulses. Our model is based on the Floquet analysis of the inelastic electron scattering on the oscillating double-layer potential, generated by the incoming laser field of long duration at the metal surface. Owing to the inherent kinematic dispersion, the propagation of attosecond de Broglie waves in vacuum is very different from that of attosecond light pulses, which propagate without changing shape. The clean attosecond structure of the current at the immediate vicinity of the metal surface is largely degraded due to the propagation, but it partially recovers at certain distances from the surface. Accordingly, above the metal surface, there exist “collapse bands,” where the electron current is erratic or noise-like, and there exist “revival layers,” where the electron current consist of ultrashort pulses of about 250 attosecond durations in the parameter range we considered. The maximum value of the current densities of such ultrashort electron pulses has been estimated to be on order of couple of tenth of mA/cm2. The attosecond structure of the electron photocurrent can perhaps be used for monitoring ultrafast relaxation processes in single atoms or in condensed matter.

The characteristics of a fast ignition heavy ion fusion (FIHIF) power plant are preliminarily evaluated. The reactor chamber consists of two sections: The upper smaller part is the microexplosion section proper; the lower bigger part is the condensation section, in which sprayed jets of coolant are injected. The first surface of the blanket is of generally accepted wetted porous design. The coolant is lithium-lead eutectic with an initial surface temperature of 820 K. The mass of the evaporated coolant just after the explosion is evaluated as 4 kg. Computation of neutronics results in blanket energy deposition with maximum density of the order of 108 J/m3 at the first wall. The heat conversion system consisting of three coolant loops provides a net efficiency of the FIHIF power plant of 0.37.

Recently the “fast ignition” method in the ICF problem was considered (Caruso & Pais, 1996). It allows increasing a target gain factor and raising reliability of the burning process. Since the required power of the irradiating beam in this method is unattainable for the traditional type of heavy ion driver with the energy of ions ≤10 GeV, the powerful laser is considered as a possible driver only. Here we investigate the fast ignition method for a system constituted from the directly irradiated cylindrical target and a powerful heavy ion driver of the charge-symmetric type (Koshkarev, 1993) in which the ions with energy ≈100 GeV and mass ≈200 are used. The actual design of a powerful heavy ion driver with the required characteristics is outside the purpose of this article. However some consideration will be given to exploring whether such a performance is within the realm of reasonable extrapolations of the present state of the art.

Popular target designs are reviewed. Possible methods of fusion target fabrication are discussed and the equipment and samples are demonstrated. The properties of the uniform and structured (cluster) materials are considered, showing the advantage of cluster material for energy conversion into soft X rays. The target materials with high content of hydrogen isotopes (BeD2, LiBeD3, or ND3BD3) prove to be more effective for high-power drivers in comparison with beryllium or polyimide.

A model of electron acceleration by an electron Bernstein mode in a parabolic density profile is developed. The mode has a Gaussian profile. It could be excited via the mode conversion of an electromagnetic wave or by an electron beam. As it attains a large amplitude, it axially traps electrons moving close to its parallel phase velocity, where parallel refers to the direction of static magnetic field. As the electrons are accelerated and tend to get out of phase with the wave, the transverse field of the mode enhances its energy and relativistic mass, increasing the dephasing length. The scheme can produce electron energies up to a few MeV.

K-α emission is an intense short-pulse line source well suited for X-ray diagnostic techniques with subpicosecond and micrometer resolution. Numerical simulations are performed here in a search for laser–target interaction regimes where both high efficiency of laser energy transformation to X-ray emission and ultrashort X-ray pulses are achieved. We use the one-dimensional PIC code for the description of the laser interaction with the plasma layer at the target surface. Fast electron transport into the target is treated by our newly developed Monte Carlo code with temporal resolution that is described here in detail. Our simulations reveal extremely short ∼200 fs FWHM bright K-α X-ray pulses emitted from targets heated by 120-fs pulses of a table-top laser. Laser energy conversion efficiency to K-α line emission as high as 6 × 10−5 is noticed. Integration of the emitted energy over the focal spot is carried out to improve the simulation accord with published experimental data. Negligible impact of self-induced electric fields on K-α emission is found for conducting target materials at moderate laser intensities [lsim ]1017 W/cm2.

Here we report on the present status of our project on statistical modelling of charge dynamics within irradiated samples. Boltzmann statistical approach to model the radiation damage in samples irradiated by FEL photons is tested in a study case of a spherically symmetric xenon cluster. Qualitative agreement between the model predictions and the experimental data is found. The results obtained demonstrate the potential of the statistical method for describing the non-equilibrium dynamics of samples exposed to FEL radiation.

The interaction of a relativistic short laser pulse with thin foil is studied using 3D PIC simulations in the context of optimized high-energy proton generation for nuclear medicine and pharmacy. As an example, we analyze the Tc-99m yield from the Mo-100(p,2n)Tc-99m reaction with the International Coherent Amplification Network (ICAN) concept defined by a 10 J pulse energy and 10 kHz repetition rate. Based on 3D PIC simulation it has been demonstrated that normally incident 100 fs laser pulse with maximum intensity of 5 × 1021 W/cm2 is able to generate 1011 protons with energy upto 45 MeV from thin semi-transparent CH2 target. Such laser-produced proton beam after 6 hours bombardment of the thick metallic Mo-100 target gives around 300 Gbq activities of Tc-99m isotope. This gives reason to believe that laser technology for producing technetium is possible with ICAN concept to replace the traditional scheme through the fission of weapons-grade uranium.

The dynamics of the plasma evolution in a dense plasma focus has been studied using a streak camera system in the soft X-ray region. The experiments were performed on a medium energy plasma focus operating with a hydrogen-argon admixture. The streak camera system employed provides nanosecond resolution and allows the plasma to be viewed simultaneously through two different filters to achieve energy resolution. Observations are made in the radial direction and along the pinch axis. Collimated X-ray PIN diodes suitably filtered were used to provide additional information on the structure of the X-ray emitting regions of the plasma. The plasma focus is observed to be totally dynamical and continuously evolving in nanosecond time scale. Hot spots are observed to form among the moving plasma at various times. Such continuous nanosecond time scale evolution of the focus pinch in the X-ray region have not been reported previously.

This article extends previous numerical studies of the stability properties of intense nonneutral charged particle beams with large temperature anisotropy (T⊥b >> T∥b) to allow for nonaxisymmetric perturbations with ∂/∂θ ≠ 0. The most unstable modes are identified, and their eigenfrequencies, radial mode structure, and nonlinear dynamics are determined.

Both dynamic and equilibrium z pinches are mostly described, whether in theory or in simulation, by conventional magnetohydrodynamic (MHD) fluid equations. However there are several key phases in z-pinch behavior when kinetic effects are important. Runaway electrons can occur close to the axis especially in an m = 0 neck or during the subsequent disruption. Large ion-Larmor orbits can, if sufficiently collisionless, lead to stabilizing effects. During a disruption, ion beams can be produced. For deuterium discharges, the interaction of an ion beam with the ambient plasma can lead to a significant neutron yield. If the drift velocity of the current-carrying electrons exceeds a threshold for generating microinstabilities (lower-hybrid or ion-acoustic instabilities), this leads to anomalous resistivity. This can occur not only during a disruption, but also in the low-density (usually outer) plasma boundary of an equilibrium or dynamic pinch. Related to this is the open question of whether current reconnection can occur in fully developed magneto-Rayleigh–Taylor instabilities in the low-density coronal plasma. Two other kinetic effects are new to z pinches. First, there are the collisions of low-density energetic ions from a wire array as they pass close to the axis to form a precursor plasma. Second, there is the possible erosion and ablation of wire cores in the necks of m = 0 coronal current-carrying plasma by flux-limited heat flow with its attendant deviation from a Maxwellian of the isotropic part of the distribution function.

This paper is devoted to the investigation of powerful laser pulse interaction with regularly and statistically volume-structured media with near critical average density and properties of laser-produced plasma of such a media. The results of the latest experiments on laser pulse interaction with plane foam targets performed on Nd-laser facilities “ABC” in the ENEA-EURATOM Association (Frascati, Italy) and “MISHEN” in the Troitsk Institute of Innovation Thermonuclear Investigations (TRINITI, Troitsk Russia), and J-laser “ISKRA-4” in the Russian Federal Nuclear Center, All-Russian Scientific Research Institute of Experimental Physics (RFNC-VNIIEF, Sarov, Russia) are presented and analyzed. High efficiency of the internal volume absorption of laser radiation in the foams of supercritical density was observed, and the dynamics of absorbing region formation and velocity of energy transfer process versus the parameters of porous matter are found. Some inertial confinement fusion (ICF) applications based on nonequilibrium properties of laser-produced plasma of a foam and regularly structured media such as the powerful neutron source with yield of 109–1011 DT-neutrons per 1 J of laser energy, laser-produced X-ray generation in high temperature supercritical plasma, and the compact ICF target absorbers providing effective smoothing and ablation are proposed.

The effect of self-focusing and defocusing on terahertz (THz) generation by amplitude-modulated Gaussian laser beam in rippled density plasma is investigated. A stronger transient transverse current is generated by transverse component of ponderomotive force exerted by laser on electrons that drives radiation at the modulation frequency (which is chosen to be in the THz domain) because of the variation in intensity in the direction transverse to the laser propagation. Numerical simulations indicate the enhancement of THz yield by many folds due to self-focusing of laser beam in comparison with that without self-focusing. The transient focusing of laser beam and its effect on the generated THz amplitude has also been studied.

Experimental data are presented showing maximum carbon C6+ ion energies obtained from nm-scaled targets in the relativistic transparent regime for laser intensities between 9 × 1019 and 2 × 1021 W/cm2. When combined with two-dimensional particle-in-cell simulations, these results show a steep linear scaling for carbon ions with the normalized laser amplitude a0 ($a_0 \propto \sqrt ( I)$). The results are in good agreement with a semi-analytic model that allows one to calculate the optimum thickness and the maximum ion energies as functions of a0 and the laser pulse duration τλ for ion acceleration in the relativistic-induced transparency regime. Following our results, ion energies exceeding 100 MeV/amu may be accessible with currently available laser systems.

The effect of magnetic field on the plasma parameters and surface modification of Cu-alloy has been investigated. For this purpose, we have employed Nd: YAG laser at various irradiances ranging from 1.9 to 5 GW/cm2 to irradiate Cu-alloy under 5 torr pressure of argon, neon, and helium. The evaluated values of excitation temperature (Texc) and electron number density (ne) of Cu-alloy plasma explored by laser-induced breakdown spectroscopy technique are higher in the presence of 1.1 Tesla magnetic field as compared with field-free case. It is true at all irradiances as well as under all environmental conditions. It is also found that trends of both Texc and ne are increasing with increasing laser irradiance from 1.9 to 4.4 GW/cm2. For the highest used irradiance 5 GW/cm2, the decrease in both parameters is observed. The analytically calculated values of thermal beta, directional beta, confinement radius, and diffusion time for laser-irradiated Cu-alloy plasma confirm the validity of magnetic confinement. Scanning electron microscope analysis is utilized to study the surface modifications of laser-irradiated Cu samples and reveals the formation of islands, craters, cones, and droplets. The finer-scale surface structures are grown in case of magnetic. It is also revealed Texc and ne play a substantial part in the growth of surface structures on Cu-alloy.

Using a combination of laser–plasma interactions and magnetic confinement configurations, a conceptual fusion reactor is proposed in this paper. Our reactor consists of the following: (1) A background plasma of boron11 and hydrogen ions, plus electrons, is generated and kept for a certain time, with densities of the order of a mg/cm3 and temperatures of tens of eV. Both the radiation level and the plasma thermal pressure are thus very low. (2) A plasma channel is induced in a solid target by irradiation with a high power laser that creates a very intense shock wave. This mechanism conveys the acceleration of protons in the laser direction. The mechanisms must be tuned for the protons to reach a kinetic energy of 300–1200 keV where the pB11 fusion cross section is significantly large (note that this value is not a temperature). (3) Those ultra-fast protons enter the background plasma and collide with boron11 to produce three alphas. Fusion born alphas collide with protons of the plasma and accelerate them causing a chain reaction. (4) A combination of an induction current and a magnetic bottle keeps the chain reaction process going on, for a pulse long enough to get a high energy gain. (5) Materials for the background plasma and the laser target must be replaced for starting a new chain reaction cycle.