The future utility of inertial confinement fusion requires a new driver. Successful experiments coupling laser energy to targets, and our understanding of fuel capsule behavior strongly suggest that a Laboratory thermonuclear source is attainable and power production may be considered if a suitable driver with high efficiency, high repetition rate, and most importantly, low capital cost, can be identified. No adequate driver exists today; however, the krypton fluoride laser holds great promise (Rosocha et al. 1986). By the end of this decade, driver development can be brought to the point that a technically justifiable choice can be made for the future direction of ICF.

Absorption, reflection and scattering of laser radiation have been studied in experiments with oblique incidence of Nd glass laser beams on plane massive targets of polyethylene, aluminium and copper. Time behaviour of 2ω and 3/2;ω harmonic intensities and their angular distributions were measured along with plasma X-ray spectra in the flux density range 1013 to 3×1014 W/cm2 for 3.5 nsec laser pulses. Comparison of the experimental data with the results of the theoretical analysis and numerical calculations is presented and relatively strong absorption of about 10% is estimated in the quarter critical density region of the plasma corona due to the two-plasmon decay instability growth. The hard X-ray component in the X-ray spectrum disappears at large angles of incidence, hence the supra-thermal electron generation and two-plasmon instability are proven to be coupled phenomena.

The interaction of femtosecond ultra-intense laser pulses with clusters increases absorption of the incident laser light compared with the interaction with solid targets and leads to enhanced generation of different quantum beams with unique parameters. Future investigations of such interaction urgently need detailed modeling and optimization of cluster parameters, for instance, in order to obtain the clusters with desired size, or some specific spatial configuration of the target etc. A numerical model of gas-cluster targets production by the nozzle flows of gases and binary mixtures is presented. Some previous results of the model utilization are summarized, and some new results are given. Techniques of experimental verification of the numerical results are discussed.

Effects of solid nanolayers embedded in a near-critical density plasma on the laser-driven collisionless shock acceleration are investigated by using two-dimensional particle-in-cell simulations. Due to the interaction of nanolayers and the incident laser, an additional number of hot electrons are generated and an inhomogeneous magnetic field is induced. As a result, the collisionless shock is reinforced within the nanolayer gaps compared to the target without the structured nanolayers. When the laser intensity is 9.8 × 1019 W/cm2, the amplitude of the electrostatic field is increased by 30% and the shock velocity is increased from 0.079c to 0.091c, leading to an enhancement of the peak energy and the cutoff energy of accelerated protons, from 6.9 MeV to 9.1 MeV and 12.2 MeV to 20.0 MeV, respectively. Furthermore, the effects of the width of the nanolayer gaps are studied, by adjusting the gap width of nanolayers, and optimal nanolayer setups for collisionless shock acceleration can be acquired.

Porous materials have peculiar characteristics that are relevant for inertial confinement fusion (ICF). Among them, chemically produced foams are proved to be able to smooth the laser inhomogeneities and to increase the coupling of the laser with the target. Foams realized with other elements and techniques may prove useful as well for ICF applications. In this work, we explore the potential of a novel class of porous materials for ICF, namely, carbon nanofoams produced with the pulsed laser deposition (PLD) technique, by means of hydrodynamic numerical simulations. By comparison with a simulation of solid-density carbon, PLD nanofoams show a higher pressure at the shock front, which could make them potential good candidates as ablators for a capsule for direct-drive fusion.

The results of experimental studies of the interactions between high-intensity 25-ps pulses from a neodymium laser and tenuous plasmas are reviewed. Electrons expelled laterally from the laser focus regions were observed to have energies of up to 1.5 keV and both the maximum electron energy and the measured electron energy spectra were found to be characteristic of acceleration by ponderomotive forces, which usually are the main part of the general nonlinear forces. These results confirmed the naive force theory and emphasized the major importance of nonlinear effects at high laser intensities.

A study is presented to find a compact X-ray laser in the spectral range of the water window. A double laser pulse method that requires a minimum energy with an optimal timing is proposed. The precreated plasma with an optimal ion distribution is heated by a short second pulse creating the required population inversion. In particular, the Ni-like 4d→4p transitions in tantalum, tungsten, and cesium are calculated.

In this paper, we report on the acceleration of protons and oxygen ions from tens of micrometer large water droplets by a high-intensity laser in the range of 1020 W/cm2. Proton energies of up to 6 MeV were obtained from a hybrid acceleration regime between classical Coulomb explosion and shocks. Besides the known thermal energy spectrum, a collective acceleration of oxygen ions of different charge states is observed. 3D PIC simulations and analytical models are employed to support the experiential findings and reveal the potential for further applications and studies.

A high-irradiance short pulsed laser was used to generate hemispherical shock waves in planar targets. A linear relationship was obtained between the laser energy for threshold spall conditions (EL) and the cubic target thickness (d): EL = 45.3d3 + 4.9, where EL is in J and d is in mm. It is found that the laser-induced ablation pressure decays with the distance to a power slightly greater than 2.

The plasma parameters of laser-ablated Zirconium (Zr) using a Langmuir probe technique have been investigated by employing a Q-switched Nd:YAG laser (532 nm, 6 ns) at various irradiances ranging from 8.6 to 15.5 GW/cm2. All the measurements have been performed under an ultra-high vacuum condition while keeping the probe at a fixed distance of 4 mm from the target. By varying the biasing voltages from 1 to 75 V, the corresponding values of electric currents are measured by the probe on the oscilloscope. Laser-induced Zr plasma parameters such as electron temperature, electron number density, plasma potential, Debye length, and thermal velocity have been evaluated from I–V characteristic curves of Langmuir probe data. It is found that both the electron temperature and thermal velocity of Zr plasma reveal an increasing trend from 18 to 41 eV and 2.8 × 108 to 4.3 × 108 cm/s, respectively, with increasing laser irradiance which is attributed to more energy deposition and enhanced ablation rate. However, the electron number density of Zr plasma exhibits a non-significant increase from 6.5 × 1014 to 6.7 × 1014 cm−3 with increasing irradiance from 8.6 to 10.9 GW/cm2. A further increase in irradiance from 12 to 15.5 GW/cm2 causes a reduction in the number density of Zr plasma from 6.1 × 1014 to 5.6 × 1014 cm−3 which is attributed to the formation of thick sheath, ambipolar electric field, and laser-supported detonation waves (Shock front). Scanning electron microscope analysis has been performed to reveal the surface morphology of irradiated Zr. It reveals the formation of cracks, ridges, cones, and grains. It was observed at high irradiances the ridges are vanished, whereas cones and cracks are dominant features. By controlling plasma parameters, surface structuring of materials can be controlled, which has a vast range of applications in the industry and medicine.

Evidence of gain in a recombining Z-pinch plasma has been obtained at 52 and 49.8 nm. The amplified XUV radiation originated from the 4f-3d and the 4d-3p transitions of Lilike oxygen, OVI. The plasmas were generated in a small diameter Z-pinch discharge with moderate currents of 40 kA. The gain coefficient was determined by variation of the pinch tube length, leading to a gain-length product of 2.5 (4f-3d) and of 2.2 (4d-3p) for a length of 9 cm.

In this article, we analyze the sensitivity of the charge and energy distribution of a swift heavy ion beam interacting with a dense plasma on the thermodynamic and dynamic properties of the target. We study more particularly partially ionized carbon targets in which both the bound and the free electrons yield a significant contribution to the stopping. The emphasis is put on direct and indirect correlation between charge transfer and stopping. We show that nonlinearities, appearing in the interaction process for heavy ions, increase the dependency of the stopping on the plasma properties, indicating that diagnostics based on the analysis of the beam ions can provide valuable information on the target properties.

Recent progress of pellet implosion research is remarkable in the obtainment of a high density (100 times solid density) and a high temperature plasma (which produces thermonuclear neutrons of 1013 per shot or a pellet gain of 0·2%) and in the corresponding understanding of the implosion physics. The data bases for laser fusion have been accumulated in preparation for a fusion ignition experiment and the achievement of break-even condition, which is estimated to be possible with 100 kJ blue laser.

The recent progress of driver technology, such as new types of solid state lasers, excimer laser, light ion beam (LIB), heavy ion beam (HIB) and free electron laser, now enabled us to design a high pellet gain experiment with a MJ driver.

The first experiments to study the shell's controlled asymmetry of capsule with DT-fuel in a highly symmetrical X-ray field, which is obtained inside a spherical hohlraum, were implemented. The asymmetry results from the coating of one hemisphere with the additional layer of material. The main goal of the experiment was to define the value of the capsule asymmetry, allowing us to experimentally obtain the neutron yield, which would be very different from the yield obtained in the experiment with the spherically symmetrical shell having the same mass as the asymmetrical one. It was shown that the shell asymmetry of ∼50% leads to the ∼(2–4) times reduction of the neutron yield as compared with the symmetrical shell. 2D calculations of the asymmetric capsule compression, using the MIMOZA-ND code, were conducted. The calculations demonstrated that the compression of targets, when exploding pusher regime occurs has a complicated character. The computational neutron yield, and the delay of the neutron generation time are in good agreement with the experimental data.

Vacuum UV fluorescences from ionic alkali-halide and rare-gas alkali excimers were observed by e-beam excitation. The two diffuse emissions centered at 185 and 154 nm from the CsF vapor were attributed to the bound-free B2Σ+ → X2Σ+ and D2Π → X2Σ+ bands of (CsF)+, respectively. And, the 164- and 133-nm diffuse bands from gas the mixture of Xe or Kr with hot vapor of Rb were assigned to the emissions of (XeRb)+ and (KrRb)+ ionic excimers. In addition, amplified spontaneous emissions of the Na2 violet, K2 yellow, and Rb2 orange diffuse bands were observed from e-beam-excited alkali vapor with argon buffer gas. The continuum spectra centered at 436, 574, and 604 nm were attributed to triplet-triplet Na2, K2, and Rb2 23Πg → 13Σu+ bound-free transitions, respectively. The dissociative recombination of Na3+, K3+, or Rb3+ is discussed as an efficient formation process of the upper states in e-beam pumping.

The interaction of intense laser light with molecules and clusters is a rapidly evolving research area. Its attraction lies in both the underlying fundamental physics and the prospects for applications. The interaction of intense laser light with rare-gas clusters, for instance, leads to megaelectron volt electrons, multikiloelectron volt ions, and bright X-ray emission. In laser-irradiated D2 clusters, thermonuclear fusion has been achieved.

This issue of Laser and Particle Beams contains the papers submitted for publication by participants of the 14th International Heavy Ion Inertial Fusion (HIF) Symposium held in Moscow, May 26–31, 2002. This conference was organized by State Research Center of Russian Federation, Institute for Theoretical and Experimental Physics, Moscow, under the auspices of the International Atomic Energy Agency, Beam Plasma and Inertial Fusion Section of the European Physical Society, and Accelerator Council of Russian Academy of Science. The symposium was supported by the Ministry of Atomic Energy of Russian Federation, Russian Academy of Science, Russian Foundation for Basic Research, International Science, and Technology Center, and by GSI Darmstadt.

We propose to build up a facility of sub-picosecond hard X-ray pulses based on Thomson scattering between femtosecond laser pulses and relativistic electrons which is a useful tool for the purpose of material investigation, plasma diagnostics, and shock wave measurement. This article reviews the principles and the development of X-ray sources based on Thomson scattering. Then New Light Source®, the Thomson scattering X-ray facility we will develop is introduced. The characteristics of a Thomson scattering X-ray source are analyzed. A computer model of the Thomson source to be developed is described in order to provide a source of the rays used in a ray tracing method, which has proved to be an essential computer tool for designing and optimizing the optical system of high brightness X-ray facilities. A code for the ray tracing source model is created based on the Monte Carlo approach. It is able to evaluate the properties and performances of the light source under development using this model. According to the simulation results, we discuss the dependence of imaging quality and source properties including spectral distribution, emittance, flux which depends on the laser and electron beam parameters, in order to check if operation performances are as expected. We also estimate the possibility of measuring the energy spectrum of a Thomson scattering source by using a crystal diffraction method. Ray tracing calculations are performed using SHADOW program package, and a new model of Thomson scattering X-ray source which can be processed in that program is established with additional code.

In this paper we compare the requirements for a light ion beam driven inertial confinement fusion (ICF) reactor with the present achievements in pulsed power technology, ion diode performance, beam transport, and target physics. The largest gap exists in beam quality and repetition rate capability of high-power ion diodes. Beam quality can very likely be improved to a level sufficient for driving a single-shot ignition facility, if the potential of two-stage acceleration is used. Present schemes for repetition rate ion diodes allow either too low power densities or create too large beam divergence. On the other hand, repetitively operating pulsed-power generators meeting the requirements for an ICF reactor driver can be built with present technology. Also, a rather mature target concept has been developed for indirect drive with light ion beams.