Temporal evolution of X-ray spectra of lead plasma produced by a CO2 laser pulse with energy of 100 J and a duration of 15 ns has been measured using a six-channel X-ray polychromator. The polychromator registered the radiation intensity in the range from 180 to 1850 eV. Plasma temperature was determined by comparison of measured results with radiation spectra obtained by numerical simulation. The values of electron temperature are in good agreement with results of hydro simulations.

Anomalous absorption of an intense short laser pulse in overdense plasmas is analyzed with a stochastic theory. A diffusion equation describing a time evolution of the electron distribution function is derived. From the equation it is shown that the electron distribution function becomes anisotropic in the momentum space, which gives rise to the absorption of the energy. The diffusion is not dominant in the pz direction, which is longitudinal to the vacuum-plasma boundary, rather it is dominant in the px direction, which is transverse to the boundary. However, the diffusion in pz enhances the absorption. Analytical expressions of the absorption coefficient and skin depth are obtained for the anomalous skin effect regime (ω02c2 << ωp2ve2), which evolves in time as the electron distribution becomes anisotropic. The asymptotic value of the absorption coefficient is proportional to [square root]I. The temperature and density dependence of the absorption coefficient is also discussed.

Supersonic jet production in conical wire array Z-pinches is modeled using a two-dimensional (2D) resistive magneto-hydrodynamic (MHD) code. In conical wire arrays, the converging plasma ablated from the wires stagnates on axis, forming a standing conical shock which redirects and collimates the flow into a jet. As the jet exits the collimator shock, it is radiatively cooled and accelerated by the steep thermal gradients present. Purely hydrodynamic simulations using conditions relevant to the MAGPIE facility show good agreement with the experiments (Lebedev et al., 2002), indicating that narrow, high Mach number (M ∼ 20), radiatively cooled tungsten jets of astrophysical relevance can be obtained. To investigate the effects of lower radiative cooling on jet collimation, we modeled an aluminum conical wire array. When radiative losses are less significant, lower Mach number (M ∼ 10), less collimated jets are obtained. MHD simulations relevant to the “Z” facility were carried out to investigate the scaling of jet parameters. The resulting hypersonic (M ∼ 40), high density jets should allow the investigation of a wider range of astrophysical jet conditions.

The beam dynamics design of the low energy DTL section of a fusion driver linac based on the IH-structure is presented. The acceleration of a 209Bi1+ beam by an IH-DTL operated at 27 MHz (54 MHz) is investigated for two specific injection energies at 60 A keV and at 200 A keV, respectively. Both cases are optimized separately, with the goal to find out the maximum achievable acceleration gradient, beam current, as well as the most attractive field strength range of the quadrupole lenses. Calculations are performed on one beamlet, but the results can be applied to build up multibeam cavities. H-mode cavities are very well suited for this purpose and provide high acceleration efficiency, especially at low particle velocity. In addition, the “Combined 0° structure” (“Kombinierte Null Grad Struktur–KONUS”) beam dynamics concept allows grouping into modular units consisting of short, simple rf cavities and of multiaperture quadrupole triplet lenses located in the intertank sections.

A new efficient injection method from a laser ion source to a Radio Frequency Quadropole (RFQ) was proposed and is being tested in RIKEN, Japan. A laser plasma is induced just before the entrance of the RFQ and is injected directly into the RFQ channel. Using an existing RFQ, first verification tests have been completed successfully. Finally, the preliminary specifications for the first RFQ dedicated to the new injection scheme are presented.

The heavy ion fusion program is developing single aperture superconducting quadrupoles based on NbTi conductor, for use in the High Current Experiment at Lawrence Berkeley National Laboratory. Following the fabrication and testing of prototypes using two different approaches, a baseline design has been selected and further optimized. A prototype cryostat for a quadrupole doublet, with features to accommodate induction acceleration modules, is being fabricated. The single aperture magnet was derived from a conceptual design of a quadrupole array magnet for multibeam transport. Progress on the development of superconducting quadrupole arrays for future experiments is also reported.

The energy spectra of heavy ions emitted from laser-produced plasmas were determined by the use of a technique relying on the implantation of plasma ions into a substrate located close to the plasma. Ion energy spectra were reconstructed from depth profiles of the implanted ions measured by the standard Rutherford back-scattering (RBS) technique employing 2 MeV alpha particles scattered at 170° laboratory angle. The energy spectra of Ag, Au, Sn, and Pb ions, implanted into aluminum or steel foils, are presented. A review of other techniques for ion energy spectrum measurement is presented and their limitations are discussed.

In this article, we present a laboratory astrophysics experiment on radiative shocks and its interpretation using simple modelization. The experiment is performed with a 100-J laser (pulse duration of about 0.5 ns) which irradiates a 1-mm3 xenon gas-filled cell. Descriptions of both the experiment and the associated diagnostics are given. The apparition of a radiation precursor in the unshocked material is evidenced from interferometry diagrams. A model including self-similar solutions and numerical ones is derived and fairly good agreements are obtained between the theoretical and the experimental results.

Beams for heavy ion fusion are likely to require at least partial neutralization in the reactor chamber. Present target designs call for higher beam currents and smaller focal spots than most earlier designs, leading to high space-charge fields. Focusing is complicated by beam stripping in the low-pressure background gas expected in chambers. One method proposed for neutralization is passing an ion beam through a plasma before the beam enters the chamber. In this article, the electromagnetic particle-in-cell code LSP is used to study the effectiveness of this form of preneutralization for a range of plasma and beam parameters. For target chamber pressures below a few milliTorr of flibe gas, preneutralization is found to significantly reduce the beam emittance growth and spot size in the chamber.

The experimental results of the investigations on the influence of external magnetic and electric fields on the characteristics of a tungsten ion stream emitted from a plasma produced by the Nd:glass laser (1 J, 1 ns) performed at IPPLM, Warsaw are presented. A negatively biased target up to −15 kV and a magnetic field up to 0.45 T were used in the experiment. A set of ion collectors and an electrostatic cylindrical ion energy analyzer located at small angles with respect to the laser beam axis and at large distances from the target were applied for ion measurements. The effect of an external magnetic field is essential to plasma expansion, but the effect of the retarding potential of the target is very weak in our experimental conditions. The aim of the studies was to prove the possibility of the optimization of ion beam parameters from laser-produced plasma for the particular application as a laser ion source coupled with the electron cyclotron resonance ion source for particle accelerators.

In this article, we present the results of the laser ion source (LIS) for heavy ion high charge state Institute of Theoretical and Experimental Physics terawatt accumulator facility. This LIS is a duty ion source of C+4 for the injector. The main parameters of CO2 laser, vacuum target chamber, ion beam high voltage extraction system, and low energy beam transport line are shown. The stability of the LIS operation is discussed and measured ion beam parameters (ion current, pulse duration, emittance) for different charge states are presented. After the upgrading of the laser cavity, high voltage capacitors, and spark gaps and the installation of a new catalyst regenerator system, the CO2 laser became much more stable and allows long term operation. LIS works about 1 × 106 shots without intervention.

One of the most exciting results recently obtained in the ultraintense interaction research area is the observation of beams of protons with energies up to several tens of megaelectron volts, generated during the interaction of ultraintense picosecond pulses with solid targets. The particular properties of these beams (high brilliance, small source size, high degree of collimation, short duration) make them of exceptional interest in view of diagnostic applications. In a series of experiments carried out at the Rutherford Appleton Laboratory (RAL) and at the Lawrence Livermore National Laboratory (LLNL), the laser-produced proton beams have been characterized in view of their application as a particle probe for high-density matter, and applied to diagnose ultraintense laser–plasma interactions. In general, the intensity cross section of a proton beam traversing matter will be modified both by collisional stopping/scattering, and deflections caused by electric/magnetic fields. With a suitable choice of irradiation geometry and target parameters, the proton probe can be made mainly sensitive to the electric field distribution in the object probed. Therefore, point projection proton imaging appears as a powerful and unique technique for electric field detection in laser-irradiated targets and plasmas. The first measurements of transient electric fields in high-intensity laser-plasma interactions have been obtained with this technique.

The main goal of the Tera Watt A Cumulator project (Institute for Theoretical and Experimental Physics, Moscow) is accumulation in the storage ring of an intense ion beam, its longitudinal compression and the use of the extracted beam for plasma experiments. However, beam parameters at the target are decreased because of extreme transverse heating and growth of the beam momentum spread due to intrabeam scattering. These effects can be suppressed by application of the electron cooling system (ECS). Design study of ECS has been performed in the Joint Institute for Nuclear Research. The design project and characteristics of the system are described, as well as analysis of the accumulation kinetics in the presence of the cooling system. Design work has shown that because of the small length of the straight section (2.35 m), the effective length of the cooling system is small (about 55–60 cm). Nevertheless, for long accumulation times (>100 s), the system allows us to significantly improve the beam parameters at the target (specific energy, specific power, and so on) and to suppress the beam losses by an order of magnitude.

A review of structural materials choices under irradiation in fusion environments is presented. Results on the neutron source term and the intensities in the structural materials as a function of pulse time, energy, and protection is given. The role of multiscale modeling for understanding the basic physics in irradiated materials is explained, and simulations of metals under pulse irradiation and SiC are reported.

This report reviews the scientific activities on high power laser and laser plasma physics at CIAE. A 6-beam KrF excimer laser system (100 J/23 ns/248 nm/1013 W/cm2, 15 min/shot) has been built, the Raman technologies used to upgrade it to 1014 W/cm2 has been studied. A UV femtosecond Ti:sapphire/KrF hybrid laser (50 mJ/220 fs/248 nm/1017 W/cm2) has been developed also, hot electron generation research has been carried out in the fs laser. In the near future, the fs laser will be amplified in six-beam laser system to produce ultra-high intensity to do fundamental researches on Fast Ignition of ICF.

Strong ionization of the gas medium has significant effects in the process of medium-order harmonic generation. The combined effect of neutral atom depletion and defocusing of the pump beam due to the intensity-dependent density of free electrons, significantly modifies the conversion characteristics and efficiency. For moderate harmonic orders, the yield is optimized for well-defined values of the pump laser intensity that do not depend on the order or on the focusing geometry, but only on the ionization potential of the gas. In particular focusing conditions, the ionization-induced defocusing can effectively guide the pump beam along channels of optimum intensity, thus enhancing the overall conversion efficiency. We demonstrate that a very simple model is able to reproduce all our experimental results in a surprisingly good way.

A six-beam multiplexing master-oscillator-power-amplifier (MOPA) high power KrF excimer laser system has been built at CIAE for fundamental research on laser–plasma interaction. The MOPA system consists of front-end, two-stage KrF amplifiers (preamplifier and main amplifier) pumped by two-side electron beams, an optical angular multiplexing system, a synchronization trigger system, and a controlling-data acquisition system and some diagnostic systems. The total energy of the six-beam output from main amplifier on the target is 100 J/23 ns, the divergence of one beam is 0.2 mrad, the focal spot diameter is 220 μm, and the focal intensity on the target is 1013 W/cm2.

We have performed a kinetic study of the electron dynamic relaxation inside a Au film subjected to a subpicosecond laser pulse. For this purpose, we have developed a time-dependent numerical solution of the Boltzmann equation for the electrons inside the film considering the collision integrals due to electron–electron and electron–phonon collisions and a perturbation term due to the laser pulse. Our results show that, after the pulse excitation, electron distributions are very far from equilibrium. Therefore it is not possible, especially in the first part of the temporal evolution, to describe the relaxation of the electron distribution through a two-temperature model.

The emissions to the atmosphere, by a heavy ion inertial fusion reactor in accidental and normal operations, are in form of tritium gas with two chemicals forms of tritium: HT and HTO. Emissions of 100% HT have been analyzed in this work, and their consequences in the dosimetry. The primary phase of the emission depends on the atmospheric conditions. As a consequence, the tritium is dispersed far from the source. The HT can be oxidized in the stratosphere or in the surface by microbiological action to convert it to HTO, and back to the air in a reemission process or penetrate into the subground. In the form of HT, the effective dose equivalent (EDE) is important in the case of intake (inhalation, skin absorption, or ingestion), because tritium is a beta emitter of low energy and the dose by external uptake is not considerable. Thus, the dose by ingestion contributes the most to the total dose in the case of HT rather than HTO. It constitutes 98% of the total EDE, in contrast with the contribution to the total dose by HTO, which is only 40%.

Two distinct issues of recent concern for ion–plasma interactions are investigated. First, the subtle connection between quantum and classical ion stopping is clarified by varying the space dimension. Then we evaluate the range of thermonuclear αS′ in dense plasmas simultaneously magnetized and compressed.