The Blumlein pulse forming line (BPFL) consisting of an inner coaxial pulse forming line (PFL) and an outer coaxial PFL is widely used in the field of pulsed power, especially for intense electron-beam accelerators (IEBA). The output voltage waveform determines the quality and characteristics of the output beam current of the IEBA. Comparing with the conventional BPFL, an IEBA based on a strip spiral type BPFL can increase the duration of the output voltage in the same geometrical volume. However, for the spiral type BPFL, the voltage waveform on a matched load may be distorted, which influences the electron-beam quality. In this paper, the output waveform of an IEBA based on strip spiral BPFL is analyzed. It is found that there is fluctuation on the flattop of the main pulse, and the flatness is increased with the increment of the output voltage. According to the time integrated pictures of the cathode holder during the operation of the IEBA, the electron emission of the cathode holder is one of the reasons to cause the variance of the flatness. Furthermore, the distribution of the current density of spiral middle cylinder of the BPFL is calculated by using electromagnetic simulation software, and it is obtained that the current density is not uniform, and which leads to the nonuniformity of the impedance of BPFL. Meanwhile, when the nonuniformity of the BPFL is taken into account, the operation of the whole accelerator is simulated using a circuit-simulation code called PSpice. It is obtained that the nonuniformity of the BPFL influences the flatness of the output voltage waveform. In order to get an ideal square pulse voltage waveform and to improve the electron beam quality of such an accelerator, the uniformity of the spiral middle cylinder should be improved and the electron emission of the cathode holder should be avoided. The theoretical analysis and simulated output voltage waveform shows reasonable agreement with that of the experimental results.

The energy spectra of electrons emitted radially from a CO2 laser focus originating from the ionization of K and Xe atoms of tenuous gas pressure are measured. We simultaneously measured the cases in which medium laser intensities and high laser intensities are applied, fitting the ADK tunneling theory.

While beam loss issues have hardly been considered in detail for heavy ion fusion scenarios, recent heavy ion machine developments in different labs (European Organization for Nuclear Research(CERN), Gesellschaft für Schwerionenforschung (GSI), Institute for Theoretical and Experimental Physics (ITEP), Relativistic Heavy-Ion Collider (RHIC)) have shown the great importance of beam current limitations due to ion losses. Two aspects of beam losses in heavy ion accelerators are theoretically considered: (1) secondary neutron production due to lost ions, and (2) vacuum pressure instability due to charge exchange losses. Calculations are compared and found to be in good agreement with measured data. The application to a Heavy-Ion Driven Inertial Fusion (HIDIF) scenario is discussed.

We examine the interaction of both cylindrical and spherical bubbles (2D) and a complex blast wave, which consists of an approaching shock/contact discontinuity/shock (Kang et al., 2001a, 2001b). Such configurations may arise following a supernova explosion, for example, SN 1987A, where a complex blast wave is presently approaching a high density “circumstellar ring” (CR) (Borkowski et al., 1997). Using simulations with the piecewise parabolic method algorithm (Colella & Woodward, 1984), we emphasize the appearance of vortex bilayers, vortex projectiles, and turbulent domains on the downstream and upstream sides of the bubble. We believe that the interfacial deformation of the CR is associated with a strong blast-wave driven accelerated inhomogeneous flow instability in a high density medium and thus will have a different character than the more common planar shock-driven Richtmyer–Meshkov instability.

Some peculiarities of using negative ions for accelerators and CTR are examined. Highpower beams of fast atoms obtained by charge exchange of negative ions can have advantages over positive ion beams for inertial confinement fusion (ICF) since they do not experience any deviations, instabilities, and scattering. H− current up to 7 kA in a 100–200 ns pulse with densities up to 200 Å/cm2 and a voltage of 0.8 MV were obtained in experiments on magnetically insulated diodes at the Lebedev Physical Institute. Diagnostics of high-power H− beams are described. Experimental results on cathode plasma formation by surface discharge on a dielectric initiated by a bipolar prepulse or by laser illumination are presented. The dependence of H− yield on cathode current was determined and experiments on plasma stabilization are described. It is concluded that 1 kÅ/cm2 of H− can be obtained.

The kinetics of the crystallization of metals from the melt under superfast cooling velocities realized in the treatment of the materials by ultrashort laser pulses is investigated. The size distribution function for crystalline phase nuclei is analytically found within the framework of the classical kinetic equation in case of superfast temperature changing. The average number of particles in the crystalline nuclei and relative volume of the crystalline phase are determined as functions of thermodynamic and laser treatment regime parameters. Good agreement is observed with experimental results for ultrashort laser pulses induced micro- and nanostructures production.

Analytical models are presented for describing modifications of the classical Rayleigh–Taylor instability theory in the context of inertial confinement fusion. The effects of stratification, finite layers, compressibility, convection and heat conduction are analysed and their mutual importance is estimated. It is found, that convective stabilization dominates for usual flow parameters and can account for growth reductions by a factor of 2 to 3. It was further possible to calculate the nonlinear evolution with the help of representative flow models and to follow the dynamics of bubble, spike and vortex formation.

Analytical interest in nitrated polycyclic aromatic hydrocarbons (nitro-PAHs) is related to their high mutagenicity and potential presence in a variety of environmental media such as diesel exhaust and urban air particulate matter. Furthermore, fundamental interest in these molecular systems stems from the photophysics of the labile NO2 functional group, which has been investigated using mass spectrometry. The nitro-PAHs, 1-nitronaphthalene, 9-nitroanthracene, and 1-nitropyrene, have been studied using both femtosecond (λ = 395 and 790 nm) and nanosecond (λ = 266 nm) lasers coupled to a reflectron time of flight mass spectrometer. Analysis of mass spectra taken over a range of intensities (1014–1015 W/cm2) has demonstrated that structurally specific ions can be observed for each molecule, with little or no fragmentation at lower intensities. It has also been found that an intact parent ion can be detected using femtosecond ionization at 395 nm in each case. This work demonstrates the potential use of laser desorption/femtosecond laser mass spectrometry (LD/FLMS) as an analytical technique for the detection of nitro-PAHs and other environmental pollutants and as a means of studying the photodynamics of labile molecular systems.

Ultrahigh axial magnetic fields have been compressed and measured in a gas-puff Z pinch. A 0·5-MA, 2–cm-radius annular gas-puff Z pinch with a 3-minute repetition rate was imploded radially onto an axial seed field, causing the field to compress. Axial magnetic field compressions up to 180 and peak magnetic fields up to 1·6 MG were measured. Faraday rotation of an argon laser (515·4 nm) in a quartz fiber on axis was the principal magnetic field diagnostic. Other diagnostics included a nitrogen laser interferometer, x-ray diodes, and magnetic field probes.

The magnetic field compression results are consistent with simple snowplow and self-similar analytic models, which are presented. The axial magnetic fields strongly affect the Z pinch dynamics. Even small axial fields help stabilize the pinches, some of which exhibit several stable radial bounces during a current pulse.

The method of compressing axial fields in a gas-puff Z pinch is extrapolable to the order of 100 MG. Scaling laws are presented. Potential applications of ultrahigh axial fields in Z pinches are discussed for x-ray lasers, inertial confinement fusion, and collimated sources of gamma radiation.

The remaining challenges, developing the relativistic electron beam sources, stimulate the investigations of cathode materials. Carbon-fiber-aluminum composite is the most appropriate cathode materials to construct the robust relativistic electron beam sources. Carbon-fiber-aluminum composite is treated by a non-equilibrium atmospheric plasma torch with a copper electrode based on high-voltage gas discharge. The axial and radial distributions of the plasma torch temperature are measured to determine the optimal treatment temperature and location. Copper-oxide particles with diameters of less than 1 µm are deposited onto the surface of the carbon-fibers and a layer of copper-oxide covers the entire surface as the treatment time is increased. Raman spectroscopy suggests that although the locations of the D and G band are similar, the areas of the D and G bands increase after the plasma treatment due to the reduced graphite crystalline size in the carbon-fibers. Analysis of the copper electrode surface discloses materials ablation arising from the discharge which releases copper from the source. Our results reveal that the atmospheric plasma torch generated by high-voltage discharge is promising in the surface modification of the carbon-fiber-reinforced aluminum composite. Further, the plasma produced by atmospheric plasma torch is dusty plasma, due to the participation of liberated copper particles. The plasma torch was analyzed by fluid dynamics, in terms of plasma density, plasma expansion velocity, and internal pressure, and it was found that the plasma produced by atmospheric torch is supersonic flow.

The formation of a collisional shock wave by the light pressure of a short-laser pulse at intensities in the range of 1018–1023 W/cm2 is considered. In this regime the thermodynamic parameters of the equilibrium states, before and after the shock transition, are related to the relativistic Rankine–Hugoniot equations. The electron and ion temperatures associated with these shock waves are calculated. It is shown that if the time scale of energy dissipation is shorter than the laser pulse duration a collisional shock is formed. The electrons and the ions in the shock-heated layer may have equal or different temperatures, depending on the laser pulse duration, the material density and the laser intensity. This shock wave may serve as a heating mechanism in a fast ignition scheme.

The emissivity of the rear of a shocked foil is spectrally and temporally resolved by coupling a transmission grating (1000 I/mm) and an X-UV streak camera (with a low density Csl photocathode), providing a high temporal resolution over a large spectral range. The shock is generated with two techniques: direct illumination of a single Al foil with a 0.26 μm wavelength laser (ablation pressure ≈ 50 Mbars) or by colliding an Al foil with a laser accelerated CH foil (generated pressures greater than 100–200 Mbars). Different thicknesses of Al are used in single foil experiments, and different initial spacing and impacted foil thicknesses are used in double foil experiments. Double foil experiments indicate that targets can be optimized for high pressure generation, and single foil experiments show that there is a radiative heat wave, around 200 eV, due to the heating of the foil by X rays emitted in the ablated region during the laser pulse. Double foil experiments have been compared with 2-D hydrodynamic Lagrangian simulations and single foil experiments have been compared with 1-D hydrodynamic Lagrangian simulations taking into account radiative heat transfer.

In this paper, we have investigated the relativistic electron acceleration by plasma wave in an axially magnetized plasma by considering the self-magnetic field effects. We show that the optimum value of an external axial magnetic field could increase the electron energy gain more than 40% than that obtained in the absence of the magnetic field. Moreover, results demonstrate that the self-magnetic field produced by the electric current of the energetic electrons plays a significant role in the plasma wakefield acceleration of electron. In this regard, it will be shown that taking into account the self-magnetic field can increase the electron energy gain up to 36% for the case with self-magnetic field amplitude Ωs = 0.3 and even up to higher energies for the systems containing stronger self-magnetic field. The effects of plasma wave amplitude and phase, the ion channel field magnitude, and the electron initial kinetic energy on the acceleration of relativistic electron have also been investigated. A scaling law for the optimization of the electron energy is eventually proposed.

Low-frequency, relativistic, subcycle solitary waves are found in two-dimensional and three-dimensional particle-in-cell (PIC) numerical simulations, as a result of the interaction of ultrashort, high-intensity laser pulses with plasmas. Moreover, nondrifting, subcycle relativistic electromagnetic solitons have been obtained as solutions of the hydrodynamic equations for an electron–ion warm plasma, by assuming the quasi-neutrality character of the plasma response. In addition, the formation of long-living macroscopic soliton-like structures has been experimentally observed by means of the proton imaging diagnostics. Several common features result from these investigations, as, for example, the quasi-neutral plasma response to the soliton radiation, in the long-term evolution of the system, which leads to the almost complete expulsion of the plasma from the region where the electromagnetic radiation is concentrated, even at subrelativistic field intensity. The results of the theoretical investigations are reviewed with special attention to these similarities.

A ns Nd:Yag laser, at intensity of 1010 W/cm2 is employed to generate carbon and aluminum non-equilibrium plasmas at a temperature of about 33 eV accelerating ions at energies of the order of 130 eV per charge state. The ion emission occurs manly along the normal to the target surface and can be detected using ion collectors employed in time-of-flight configuration. The application of magnetic field along the axe of the ion emission permits to focalize the ion emission enhancing the detected ion current. The formation of electron traps, due to the magnetic force lines, drives the ion acceleration improving their kinetic energy. Different applications can make use of these results to increase the flow of charged particles and their energy employing appropriate static magnetic fields, as it will be presented and discussed.

An analysis is made of the equation of state problems in inertial confinement fusion. After reviewing the need for compression for inertial confinement fusion along the lines of the classical self similarity model which is derived in a modified way with indications of the equation of state, the problems of the central core ignition are examined with respect to the equation of state. A basic difficulty is elaborated in the ‘scape goat diagram’. After describing alternative compression schemes such as non-linear force and cannon ball, the two temperature equation of state is developed with electronic and ionic contributions following the ideal gas, the Debye-Grüneisen equation of state, the solid-gas interpolation and the SESAME tables. A remarkable discrepancy for the isothermal diagrams is shown between the general result and the result based on the earlier McCarthy–Kalitkin scheme.

The calculation of the multigroup opacities using several different atomic physics models is the main goal of this work. The atomic data, such as energy levels, bound-electron populations, oscillator strengths and effective charges are worked out by two atomic physics models using the average-atom concept. The result achieves multifrequency opacities. These are weighted with the Planck function or the real radiation field, making up finally the multigroup opacities in the selected number of groups.

Recently, we have developed a one-dimensional radiation-hydrodynamics code called SARA that implicitly solves the multigroup radiation transport equations. A high-order differencing algorithm as well as multifrequency-grey synthetic acceleration techniques are used to obtain a robust algorithm that can be extensively used for radiation energy transport problems and radiative regimes.

The major goal of writing this code has been to explore the performance of the indirectdrive light ion beam capsules. Numerical results show that the efficiency of the energy conversion into soft X rays and the power flux amplification factor are high enough to efficiently compress the fuel capsule for a wide range of ion beam parameters.

Multi-MeV proton beams can be generated by irradiating thin solid foils with ultra-intense (>1018 W/cm2) short laser pulses. Several of their characteristics, such as high bunch charge and short pulse duration, make them a complementary alternative to conventional radio frequency-based accelerators. A potential material science application is the chemical analysis of cultural heritage (CH) artifacts. The complete chemistry of the bulk material (ceramics, metals) can be retrieved through sophisticated nuclear techniques such as particle-induced X-ray emission (PIXE). Recently, the use of laser-generated proton beams was introduced as diagnostics in material science (laser-PIXE or laser-driven PIXE): Coupling laser-generated proton sources to conventional beam steering devices successfully enhances the capture and transport of the laser-accelerated beam. This leads to a reduction of the high divergence and broad energy spread at the source. The design of our hybrid beamline is composed of an energy selector, followed by permanent quadrupole magnets aiming for better control and manipulation of the final proton beam parameters. This allows tailoring both, mean proton energy and spot sizes, yet keeping the system compact. We performed a theoretical study optimizing a beamline for laser-PIXE applications. Our design enables monochromatizing the beam and shaping its final spot size. We obtain spot sizes ranging between a fraction of mm up to cm scale at a fraction of nC proton charge per shot. These results pave the way for a versatile and tunable laser-PIXE at a multi-Hz repetition rate using modern commercially available laser systems.

The nuclear-pumped laser program at the Institute for Technical Physics at Chelyabinsk- 70 is described. Work has primarily concentrated on rare gas and metal vapor lasers.