By employing analytic solutions for the electromagnetic field at resonance absorption, first derived by Denisov, the total nonlinear force, in the plane of incidence has been evaluated. This 2-D force results in a conical type emission towards the vacuum and into the plasma which depends critically on the collision frequency and the density scale length. It is found that, for neodynium glass laser intensities of 1014 W/cm2, keV ions can be produced by nonlinear force acceleration. The analysis is limited by the following requirements: the dielectric constant varies linearly with distance, the angle of incidence is not too small and most importantly self consistent and transient wave processes occur at a later time and are neglected.

The dynamics of low entropy weak shock waves induced by heavy ion beams in solid targets was investigated by means of a schlieren technique. The targets consist of a metallic absorber for the beam energy deposition followed by a plexiglass block for optical observations. Multiple waves propagating with supersonic velocities at 15 kbar pressures were observed in the plexiglass, for pressures of up to 70 kbar numerically calculated in the absorbers. Pressures in the megabar ranges are predicted for a near future beam upgrade, enabling studies of phase transition to metallic states of H, Kr, and Xe.

(This article appeared in Volume 24, Number 2, Pages 275–282, 2006)

(This article appeared in Volume 24, Number 2, Pages 275–282, 2006)

Below is the correct Reference citation for Breil et al. (2005)

Breil, J., Hallo, L., Maire, P.H. & Olazabal-Loumé, M. (2005). Hydrodynamic instabilities in axisymmetric geometry self-similiar models and numerical simulations. Laser Part. Beams.23, 155–160.

Response of clusters to laser radiation depends on the laser parameters like wavelength, pulse duration, field, and so forth. At moderate laser intensities, I ∼ 1012 W/cm2, using a laser beam of wavelength 1.06 μm and 10-ns pulse duration, we have studied X-ray emission spectra from aluminum clusters of diameter 0.4 μm and gold clusters of 1.25 μm. Aluminum clusters show a different spectra compared to bulk material whereas gold clusters evolve towards bulk gold. Results are analyzed on the basis of cluster dimension, laser wavelength, and pulse duration. At higher laser intensities ≥1018 W/cm2, clusters undergo Coulomb explosion, giving rise to energetic electrons and ions. Here we discuss the possibility of harnessing these energetic particles for heating a small volume of the precompressed DT fuel to ignition condition relevant to fast ignition. Preliminary results are discussed.

A theoretical and experimental study of line broadening and merging is presented and suggested for diagnosis of high density laser plasmas. For densities larger than 1022 cm−3 the hydrogenlike sequence is reduced to four lines for the emitter ion with ZE = 9. The perturbation effects on the latter come mainly from the interaction with plasma ions and electrons (Stark effect, multipolar interactions, ionization by tunnel effect, polarization line shift …).

Physics of Inertial Fusion: Beam Plasma Interaction, Hydrodynamics, Hot Dense Matter, Stafano Atzeni and Jürgen Meyer-ter-Vehn, Clarendon Press, 2004, 458 pages, ISBN: 0198562640

This book has several remarkable highlights summarized on laser produced plasmas and particle beam driven fusion energy. In contrast to the usual books, the nuclear fusion reactions are presented with very detailed experience, including pycnonuclear reactions, spin polarization, and mentioning the 25 orders of magnitude less probable weak force pp-reaction than DT. There is a rather comprehensive collection of the conditions of confinement, spherical implosion, ignition burn, and gain. Hydrodynamics is based on a one fluid model, not Schlüter's space charge quasi-neutral two-fluid model nor the genuine two-fluid treatment. Hohlraum targets are covered and the fast ignition (FI) contains the forte of the authors' own achievements though the entire problems shown experimentally or theoretically (Mulser et al., 2004) are not discussed nor the new aspects on FI known before finishing the book (Hora, 2004). The 36 pages for the entire physics of (laser- and particle-) beam-target interaction are used to sketch at least the most important aspects.

Collisionless shocks have been the subject on many studies in recent years, due to their ability to accelerate particles. In order to do so, a shock must fulfill three criteria. First, it must be strong enough to accelerate particles efficiently. Second, both the upstream and the downstream must be collisionless. Third, the shock front must be surrounded by electromagnetic turbulence capable of scattering particles back and forth. We here consider the encounter of two identical plasma shells with initial density, temperature, and velocity n0, T0, v0, respectively. We translate the three criteria to the corresponding requirements on these parameters. A non-trivial map of the allowed region for particle acceleration emerges in the (n0, T0, v0) phase space, especially at low velocities or high densities. We first assess the case of pair plasma shells, before we turn to electrons/protons.

The possibility of heavy-ion beam-pumped ion lasers is demonstrated by observation of optical gain on the 476.5-nm Ar II 4p–4s ion laser transition in argon gas excited by 2.5–ns pulses of 110–MeV 32S ions with repetition rates up to 156 kHz. The particle energy per pulse was about 20 μJ. The projectiles were stopped in the target at pressures between 5 and 35 kPa. The beam from an argon ion probe laser operated at 476.5 nm was used to determine gain amplitude and time structure from a measured transient increase of the probe laser intensity when target excitation by the ion beam was present. The maximum gain observed was (0.5 ± 0.1) x 10-3 at a target gas pressure of 5 kPa. The optical gain observed in argon is consistent with calculations based upon an analysis of spectroscopic studies of rare gas targets excited by heavy-ion beams.

The anisotropic wave collapses governed by the Zakharov equations or by the nonlinear Schrödinger equation are investigated by means of a transformation group exhibiting self-similar anisotropic solutions characterized by two contraction rates. We show the existence of two infinite sets of anisotropic self-similar collapses corresponding, respectively, to “pancake” (oblate) and “cigar” (oblong) shaped collapsing solutions. Both of these classes of anisotropic structures are furthermore shown to be bounded from below by two peculiar solutions whose validity extends from the subsonic to the supersonic regime (the so-called “trans-sonic” solutions) and from above by the standard isotropic solutions. Spatial profiles of trans-sonic anisotropic solutions are analytically derived.

The phase shift's influence of two strong-pulsed laser waves on effective interaction of electrons was studied. Considerable amplification of electron repulsion in the certain range of phase shifts and wave intensities is shown. That leads to electron scatter on greater distances than without an external field. The value of the distance can be greater on 2–3 order of magnitude. Considerable influence of the phase shift of pulses of waves on the possibility of effective attraction of electrons is also shown.

Models for the prediction of electron pedestal temperatures at the edge of type I ELMy H-mode plasmas are developed. These models are based on theory motivated concepts for pedestal width and pressure gradient. The pedestal pressure gradient is assumed to be limited by high n ballooning mode instabilities, where both the first and second stability limits are considered. The effect of the bootstrap current, which reduces the magnetic shear in the steep pressure gradient region at the edge of the H-mode plasma, can result in access to the second stability of ballooning mode. In these pedestal models, the magnetic shear and safety factor are calculated at one pedestal width away from separatrix. The predictions of these models are compared with the experimental electron pedestal temperatures for type I ELMy H-mode discharges obtained from the latest public version (version 3.2) in the International Tokamak Physics Activity Edge (ITPA) Pedestal Database.

The spectra of laser-produced plasmas of various materials of Z>70 have been interpreted as spin-orbit-split arrays of the 3d – 4f and 3d – 5f transitions for Ni-like to Ge-like ions. The excellent agreement between the model and the experiments indicated the possibility of their use for plasma diagnostics. First results from targets of Gold alloyed with Aluminium give an alternative diagnostic.

We report on a new technique that we used to accurately time the velocity of a cluster beam. It involves deflecting particles away from their usual beam path by scattering with an ablation plume. We were able to time the occurrence of a C60 cluster beam to better than 0.2%. This technique was critical in recent light-force polarizabilities experiments.

The paper presents a cylindrical diode with a rod anode for repetitive pulsed intense X-ray sources. The diode uses a massive anode of diameter 1 cm, thus increasing the lifetime of the energy converter. The diode gap is preliminary filled with ions produced by cathode flare in a vacuum discharge, allowing electron beam pinching at a voltage of <200 kV. In the mode of pinching, the diode is an efficient source of high-power X rays. At a distance of 20 cm from the X-ray source, the radiation dose per pulse is 0.4 R at a peak power of 7 × 106 R/s. The full-width at half-maximum of the radiation pulse is 40 ns. The power in the diode is 1.8 GW at a beam current of 10 kA and exceeds the maximum power of the generator operating onto a matched load with constant resistance.

Particle beams with uniform and well-confined intensity distributions are desirable in some high power beam applications to prolong the target lifetime or to improve the beam utilization. Three kinds of elements had been proposed for the beam homogenizing, such as octupole, pole-piece magnet, and step-like nonlinear magnets. In this paper, the new type of elements called heteromorphic quadrupole and focus sextupole are proposed. The Gaussian-like multiparticle beam redistribution by the octupole, heteromophic quadrupole, step-like nonlinear magnets, and focus sextupole has been simulated by the POISSON and LEADS code. The best redistribution result is obtained by the focus sextupole, and one of the solutions of redistributing beam with big halo can be that of using the focus sextupole and the heteromorphic quadrupole.

The collimated electron jets ejected from cylindrical plasma are produced in particle-in-cell simulation under the applied longitudinal magnetostatic field and radial electrostatic field, which is a process that can be conveniently performed in a laboratory. We find that the applied magnetostatic field contributes significantly to the jet collimation, whereas the applied electrostatic field plays a vital role in the jet formation. The generation mechanism of collimated jets can be well understood through energy gain of the tagged electrons, and we conclude that the longitudinal momentum of the electrons is converted from the transverse momentum via the transverse-induced magnetic field. It has been found that the ejecting velocity of the jets is close to the speed of light when the applied electrostatic field reaches 3 × 1010 V/m. The present scheme may also give us an insight into the formation of astrophysical jets in celestial bodies.

A novel way for igniting small thermonuclear assemblies by inertial confinement is proposed, by replacing the positive mass of an imploding dense star with the negative mass in the reference frame of a rapidly rotating thermonuclear target. According to Einstein's general theory of relativity, this negative mass can be orders of magnitude larger than the positive mass density of a neutron star. This novel concept also replaces the Plutonium 239 “spark plugs” of large thermonuclear devices with a shell of natural uranium surrounding a target composed of DT or Li6D.

Unlike the ignition by a laser – or particle beam – induced spherical implosion, this configuration, similar to that of an imploding star is not only Rayleigh–Taylor stable, but it can be realized with intense relativistic electron or ion beams, with an energy of about 100 MJ, having a short range in the dense high Z natural uranium shell.

The increase in time-integrated divergence of a 1.7-MeV, 10-MA relativistic electron beam due to transport over 10 cm in a gas cell filled with 1 and 6 Torr of nitrogen was measured. The divergence was characterized by a multiple-pinhole beam sampling technique involving an aperture plate, an expansion region, and an attenuator plate followed by nylon radiochromic film. The divergence is determined by a fit of the measured deposition profile to response functions calculated using Monte Carlo coupled electronphoton transport codes. The initial value of 6.9° after the entrance foil is observed to increase to 12°. The errors in the measurement are quantified with Monte Carlo techniques. The response function fit gives a significantly better estimate of the divergence than a Gaussian fit.

High-intensity femtosecond laser–plasma interaction experiments were performed to investigate laser–plasma wakefield acceleration in the “bubble” regime. Using a 15 TW laser pulse, the emission of side-scattered radiation was spectrally and spatially resolved and was consequently used to diagnose the evolution of the laser pulse during the acceleration process. Side-scattered emission was observed immediately before wavebreaking at a frequency of ωL + 1.7ωp (where ωL is the laser frequency and ωp is the background plasma frequency). This emission may result from scattering of laser light by large amplitude plasma oscillations generated in the shell of the wakefield “bubble” and which occurs immediately prior to the wavebreaking/injection process. The observed variation of the frequency of scattered light with electron density agrees with theoretical estimates.