The first International Conference on the Frontiers of Plasma Physics and Technology was organized in Bangalore, India during December 9–14, 2002. More than 100 delegates from all the continents participated in the conference and about half the delegates were from overseas. This Forum specially encouraged the young researchers to present their work and exchange ideas with experts. This conference which was inter-disciplinary in nature, brought several plasma physicists and technologists to a common platform to discuss the research and applications useful for the advancement of the present society.

Shock pressure generated in aluminum targets due to the interaction of 0.44 μm (3 ω of iodine laser) laser radiation has been studied. The laser intensity profile was smoothed using phase zone plates. Aluminum step targets were irradiated at an intensity I ≈ 1014 W/cm2. Shock velocity in the aluminum target was estimated by detecting the shock luminosity from the target rear using a streak camera to infer the shock pressure. Experimental results show a good agreement with the theoretical model based on the delocalized laser absorption approximation. In the present report, we explicitly discuss the importance of target thickness on the shock pressure scaling.

Optical field ionization is the earliest and fastest plasma-generating process during the interaction of intense laser light with matter. By using short and rapidly rising laser pulses, the free electron density may turn from being transparent for an incoming laser pulse to reflective in less than half a laser cycle, that is, on a subfemtosecond timescale. Extremely nonlinear optical effects arise as a consequence of this. In this article, the basics of optical field ionization that are relevant in analytical or numerical studies of intense laser–matter interactions are reviewed. Several macroscopic effects of field ionization in the interaction of intense laser pulses with solid targets are briefly surveyed.

A systematic investigation of the longitudinal fields excited in a plasma by a short, dense beam of positrons is carried out using two-dimensional, cylindrical geometry, particle-in-cell code simulations. In particular, we examine the behavior of the accelerating and decelerating fields of the wakefield as a function of beam charge, radius, length, and plasma density. The parameters are chosen to be consistent with those employed in current and future experiments designed to elucidate the physics of positron beam–plasma interactions.

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.

Soft X-ray contact microscopy (SXCM) experiments have been performed using the Prague Asterix Iodine Laser System (PALS). Laser wavelength and pulse duration were λ = 1.314 μm and τ (FWHM) = 450 ps, respectively. Pulsed X rays were generated using teflon, gold, and molybdenum targets with laser intensities I ≥ 1014 W/cm2. Experiments have been performed on the nematodes Caenorhabditis elegans. Images were recorded on PMMA photo resists and analyzed using an atomic force microscope operating in contact mode. Our preliminary results indicate the suitability of the SXCM for multicellular specimens.

The generation of high harmonics in laser–plasma interactions on the steep density gradients is discussed, especially by using short-pulse UV laser radiation. Low intensity experiments with 5·1015 W/cm2 generate harmonics in the VUV range, and the efficiency can be optimized by modifying the density gradient. To obtain higher harmonics and to clear some disagreements among different results concerning polarization properties of harmonics we switched for higher intensities. Our experimental arrangement makes it possible to obtain a 5·1017 W/cm2 intensity with a prepulse as low as 107 W/cm2 using a table-top system. Preliminary results and future trends for high-harmonics generation with this method are given.

We have simulated the shock Hugoniot of copper and uranium based on the results of first principles electronic structure calculations. The room temperature isotherm has been obtained by evaluating the accurate ground state total energies at various compressions, and the thermal and electronic excitation contributions were obtained by adopting isotropic models using the results obtained by the band structure calculations. Our calculations ensure smooth consideration of pressure ionization effects as the relevant core states are treated in the semi-core form at the ambient pressure. The pressure variation of the electronic Grüneisen parameter was estimated for copper using the band structure results, which leads to good agreement of the simulated shock Hugoniot with the measured shock data. The simulation results obtained for U are also compared with the experimental data available in literature and with our own data.

At the frontier of plasma physics and technology are applications of laser-generated plasmas to laboratory simulations of astrophysical phenomena and to industrial processing. This article presents work at the Naval Research Laboratory in both of these areas. We show how laser plasmas are used to measure a blast wave corrugation overstability important in astrophysics. Detailed atomic physics calculations of radiative cooling within the blast front are used to develop a criterion of the existence of the overstability and are used to explain the experimental results. The criterion depends on quantities such as element abundances, densities, temperatures, and blast wave velocities—quantities which can be measured spectroscopically—and therefore used to infer whether astrophysical blast wave nonuniformities are the result of this instability. In other experiments, high-velocity jets are formed in the laboratory using miniature hollow cones. Jets produced by these cones are used to study the physics of jets occurring in supernovae and in star-forming accretion disks. In industrial semiconductor processing, annealing, that is, removing crystal damage and electrically activating the semiconductor, is a critical step. Industrial annealing techniques most often utilize heat generated by an oven, flash lamps, or a low-power laser. During such heating dopants within the semiconductor lattice diffuse and spread. This degrades the performance of circuits in which the individual circuit elements are very close to each other. We are developing an annealing technique in which shock or sound waves generated by a laser plasma are used to anneal the semiconductor. We have demonstrated that the method works over small areas and that it does not lead to significant dopant diffusion.

X rays emitted from Kr clusters illuminated by a femtosecond laser have been observed over a wide spectral region from 3 keV to 15 keV. The measured spectra are characterized by a broad bremsstrahlung continuum and Kα, β lines at 12.66 keV and 14.1 keV. To the best of the authors' knowledge, this is the first observation of Kα, β emission from laser-heated Kr clusters. The bremsstrahlung continuum arising from collisions in the plasma implies a population of hot electrons consistent with a temperature of several kiloelectron volts. The absolute X-ray yield in the 3–15 keV region is found to be of the order of 107 photons per laser pulse. The plasma temperature, estimated from the continuum part of the spectrum as a function of laser intensity and X-ray yield as a function of laser pulse duration, are studied.

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.

We have performed an initial assessment of the feasibility of producing heavy negative ion beams as drivers for an inertial confinement fusion reactor. Negative ion beams offer the potentially important advantages relative to positive ions that they will not draw electrons from surfaces and the target chamber plasma during acceleration, compression, and focusing, and they will not have a low energy tail. Intense negative ion beams could also be efficiently converted to atomically neutral beams by photodetachment prior to entering the target chamber. Depending on the target chamber pressure, this atomic beam will undergo ionization as it crosses the chamber, but at chamber pressures at least as high as 1.3 × 10−4 torr, there may still be significant improvements in the beam spot size on the target, due to the reduction in path-averaged self-field perveance. The halogens, with their large electron affinities, are the best negative ion candidates. Fluorine and chlorine are the easiest halogens to use for near-term source experiments, whereas bromine and iodine best meet present expectations of driver mass. With regard to ion sources and photodetachment neutralizers, this approach should be feasible with existing technology. Except for the target chamber, the vacuum requirements for accelerating and transporting high energy negative ions are essentially the same as for positive ions.

The assembly of the Paul Trap Simulator Experiment (PTSX) is now complete and experimental operations have begun. The purpose of PTSX, a compact laboratory facility, is to simulate the nonlinear dynamics of intense charged particle beam propagation over a large distance through an alternating-gradient transport system. The simulation is possible because the quadrupole electric fields of the cylindrical Paul trap exert radial forces on the charged particles that are analogous to the radial forces that a periodic focusing quadrupole magnetic field exert on the beam particles in the beam frame. By controlling the waveform applied to the walls of the trap, PTSX will explore physics issues such as beam mismatch, envelope instabilities, halo particle production, compression techniques, collective wave excitations, and beam profile effects.

We describe the next set of experiments proposed in the U.S. Heavy Ion Fusion Virtual National Laboratory, the so-called Integrated Beam Experiment (IBX). The purpose of IBX is to investigate in an integrated manner the processes and manipulations necessary for a heavy ion fusion induction accelerator. The IBX experiment will demonstrate injection, acceleration, compression, bending, and final focus of a heavy ion beam at significant line charge density. Preliminary conceptual designs are presented and issues and trade-offs are discussed. Plans are also described for the step after IBX, the Integrated Research Experiment (IRE), which will carry out significant target experiments.

It is shown that beyond a virtual cathode the current of a magnetized steady-state thin annular electron beam in a drift tube may range from zero to the limiting current of the tube.

This article presents an effect of cross focusing of two laser beams on the growth of a laser ripple in laser-produced plasmas. The mechanism of nonlinearity is assumed to be ponderomotive force, arising because of the Gaussian intensity distribution of the laser beams. The dynamical equation governing the laser ripple intensity has been set up and a numerical solution has been presented for typical laser plasma parameters. It is found that the change in the intensity of the second laser beam can affect the growth of the laser ripple significantly.

Energetic protons are emitted from thin foils irradiated by short laser pulses at high intensities. One- and two-dimensional particle-in-cell simulations have been used to study the influence of initial proton position, laser irradiance, and target density profile on this ion acceleration. These simulations bring additional support to the idea that protons are mainly accelerated from the rear side of the target, by electrostatic fields associated with hot electrons escaping into vacuum. The density scale length at the front of the target appears to be the main parameter to increase proton energies when the laser irradiance is fixed.

The excitation of large-amplitude plasma waves by intense few-cycle laser pulses in thin overdense plasma layers is studied using one-dimensional particle-in-cell simulation. P-polarized pulses generate relativistic electron pulses (jets) at the irradiated surface that penetrate the layer and then oscillate back and forth due to reflection by self-generated space charge fields building up in front of the surfaces. Counterpropagating plasmons of large amplitude are excited and start to emit radiation at 2ωp and other harmonics of the plasma frequency. The analogy to type III solar radio emission that is driven by electron bursts from deeper layers of the solar corona is pointed out; it highlights the present topic as another example of laboratory astrophysics with lasers.

By using an effective dielectric constant to modify the nanoplasma model, the interactions of large Ar clusters with high-intensity femtosecond laser pulses have been studied. It is shown that the resonance absorption mechanism plays a predominant role in the production of highly energetic argon ions, and the calculated mean kinetic energy of Ar ions is in good agreement with our previous experimental results. The scaling of mean kinetic energy and charge states of Ar ions against cluster size and laser intensity has also been analyzed. The results indicate the existence of optimum cluster sizes and optimum laser intensities where the best coupling efficiency of the laser energy can be obtained.

Bremsstrahlung is one of the most important energy loss mechanisms in achieving ignition, which is only possible above a threshold in temperature for a given fusion reaction and plasma conditions. A detailed analysis of the bremsstrahlung process in degenerate plasma points out that radiation energy loss is much smaller than the value given by the classical formulation. This fact seems not useful to relax ignition requirements in self-ignited targets, because it is only relevant at extremely high densities. On the contrary, it can be very positive in the fast ignition scheme, where the target is compressed to very high densities at a minimum temperature, before the igniting beamlet is sent in.