Thermonuclear ignition and burn propagation in pre-compressed cylindrical deuterium-tritium (DT) targets is studied by two-dimensional radiation hydrodynamics simulations using the code MULTI-2D. Special attention is paid to self-sustained steady burn wave propagation. Peak temperatures and burn wave velocity scale with the density-radius product of the fuel, and wave propagation is obtained for (ρR)DT ≥ 0.45 g/cm2. Radiation transport is identified as the dominant mechanism to drive the wave. Details of ignition by a heavy ion beam pulse are also presented. Limitations in the physics basis of the simulations are pointed out. The results are compared with previous publications found in the literature.

A spherical target irradiated by laser beams located at 49o and 131° with respect to the polar axis has been considered. The illumination model has been used to evaluate the irradiation non-uniformity assuming circular and elliptical super-Gaussian laser intensity profiles and the irradiation scheme has been optimized by means of the polar direct drive technique. A parametric study has been performed providing the irradiation non-uniformity as a function of the polar direct drive displacement and of the laser intensity profile parameters. Moreover, two-dimensional axis-symmetric hydrodynamic simulations have been performed for a plastic sphere irradiated by laser beams characterized by a constant flat temporal power pulse. In these simulations, the front of the inward shock wave has been tracked providing the time-evolution of any non-uniformity. The results provided by the two methods — illumination model and hydrodynamic data — have been compared and it is found that the illumination model reproduces the main behavior exhibited by the hydrodynamic data. The two models provide compatible values for the optimum polar direct drive parameter and similar optimal super-Gaussian profiles.

Laser generated plasmas from target normal sheath acceleration produce energetic ions from the rear side of the target due to the formation of a high directive electric field. Fast electrons are ejected from the rear side of the target and a successive Coulomb explosion is driven by the fast electrons generating a high electric field of double layer. The ion acceleration is mainly controlled by the laser intensity and by the square of the laser wavelength. Literature reports that at intensities of the order of 1018 W/cm2 and at wavelengths of about 1 µm the ion energy is of the order of 5 MeV/nucleon. The use of advanced targets realized with the aim to reduce the surface reflection, to increase the laser absorption coefficient and, with an optimal thickness, to increase the electric field of the double layer, permits to enhance the ion energy acceleration, so that the energy of 5.0 MeV per charge state can be reached at about 1016 W/cm2, as it will be presented and discussed.

This paper analyzes the one dimensional shock wave created in a planar target by the ponderomotive force induced by very high laser irradiance. The laser-induced relativistic shock wave parameters, such as compression, pressure, shock wave and particle flow velocities, sound velocity and temperature are calculated here for the first time in the context of relativistic hydrodynamics. For solid targets and laser irradiance of about 2 × 1024 W/cm2, the shock wave velocity is larger than 50% of the speed of light, the shock wave compression is larger than 4 (usually of the order of 10) and the targets have a pressure of the order of 1015 atmospheres. The estimated temperature can be larger than 1 MeV in energy units and therefore very excited physics (like electron positron formation) is expected in the shocked area. Although the next generation of lasers might allow obtaining relativistic shock waves in the laboratory this possibility is suggested in this paper for the first time.

Analytical and numerical investigation of the reflection and transmission of a counter-propagating relativistically strong laser pulse from a relativistically flying dense plasma double-sided mirror is studied. We assume that the incident laser pulse is short, so that we can neglect the slow ion dynamics and consider the electron motion only. Numerical results of the amplitudes of the reflected/transmitted electric fields from a uniformly moving mirror, accelerated mirror, and oscillating mirror are obtained. Fourier spectrum of the reflected intensity from the moving mirror shows that the intensity decreases with increase in the frequency. The reflected pulse has an up-shifted frequency and increased intensity. It is seen that the first few cycles of the reflected radiation exhibit presence of high harmonics, while the later cycles are compressed together with harmonics in comparison with the earlier cycles. The variation of the reflection coefficient for a uniformly moving mirror as a function of the thin foil plasma-density parameter is numerically studied.

This paper presents an investigation of self-focusing of intense Gaussian rippled laser beam in collisionless plasma by including the nonlinearity associated with the relativistic mass and the ponderomotive force and its effects on the excitation of ion acoustic wave. The growth of ripple, riding on an intense Gaussian laser beam in plasma and its coupling with ion acoustic wave has also been studied. Modified coupled equations for main laser beam, growth of laser ripple in plasma, rippled laser beam, beam width, and density perturbation associated with ion acoustic wave are derived using Wentzel-Kramers-Brillouin and paraxial ray approximation. These coupled equations are solved analytically and numerically to study the laser intensity in plasma and the variation of amplitude of the ion acoustic wave for various established laser and plasma parameters. From numerical computation, it is observed that both nonlinearities significantly affected the dynamics of the growth of laser ripple in plasma, propagation of rippled laser beam as well as ion acoustic wave in plasma at high laser power flux. The growth of laser ripple increase with increase in the intensity of laser beam and due to the contribution of growth rate, intensity profile of rippled laser beam and ion acoustic wave modified accordingly.

In this work, the effect of electron trapping on the self-similar expansion of electron-ion laser plasma into vacuum, combined with the effect of non-thermal (energetic) electrons is studied. For this, a mono-dimensional, non-relativistic model where the ions are cold and governed by fluid equations is used. In the approximation of quasi-neutrality of charge, the obtained self-similar solution shows that for ion (plasma) behavior, the presence of an important number of non-energetic trapped electrons in the plasma potential wells has the effect of slowing down the expansion, whereas the phenomenon of presence of energetic electrons makes the influence of trapping effect on the self-similar expansion very weak even in the case of a very small number of energetic electrons. This study is of interest in the context of the investigation of mono-energetic ion beams from intense laser interactions with plasmas.

Laser surface melting is one of the most important processes in laser material processing. Selective vaporization of alloying elements in laser melting offers fundamental understanding of laser processing on metallic alloys. This work provides linkage between laser melting and material properties using secondary ion mass spectrometry (SIMS) for tiny vaporized species in laser-generated plume and energy dispersive spectroscopy (EDS) for solid solution range in molten pool, both qualitatively and quantitatively (up to hundreds of micron). Silicon wafer was used to collect the generated plume. Chemical analysis was carried out on top surface and sub-surface of the deposited plume. Transport behavior as well as distribution of the vaporized species inside the plume was further proposed.

Particle acceleration is an important tool in material modification and several other applications. There are multiple techniques to generate and accelerate ion beams. In the current research work, ions emitted from laser induced plasma were accelerated by employing a DC high voltage extraction assembly. The Nd:YAG laser (1064 nm) with 10 mJ energy and 12 ns pulse width was irradiated on Aluminum target. Thomson parabola technique using Solid State Nuclear Track Detector (CR-39) was employed for measurement of ions energy generated from laser induced plasma. In response to a stepwise increase in acceleration potential from 0–10 kV, an evident increase in energy, in the range 627–730 keV, was observed. In order to utilize this facility as an ion source, Aluminum was exposed to these ions. The Optical and AFM micrographs revealed that the damage produced by the ions on Al surfaces, become more prominent with the increase in ion energy. TRIM simulations were performed for the analysis of the damage at the irradiated samples. Changes in the total displacements, target vacancies and replacement collisions, calculated by TRIM simulation, were analyzed for ion irradiations with increasing ion energies.

The development of very high power laser opens up new horizons in a various field, such as protontherapy in medicine or laser-matter interaction in physics. The Target Normal Sheath Acceleration phenomenon is used in the first one. After the laser-matter impact, a plasma is generated, and free electrons move forward. It creates an electrostatic field, which can accelerate protons at the rear side of the target. The generated beam can be able to contain energetic protons with a large spectrum(1–200 MeV). This energy distribution depends on the laser power and the nature of the target. This technique has been validated by accelerating protons coming from hydrogenated contaminant (mainly water) at the rear of metallic target up to 58 MeV at Lawrence Livermore National Laboratory using the Nova Petawatt laser. However, several laser teams would like to study this interaction with pure targets. In this context, the low temperature laboratory, at CEA-Grenoble has developed a cryostat able to continuously produce a thin hydrogen ribbon (50 and 100 μm thick). A new extrusion concept, without any moving part has been carried out, using only the thermodynamic properties of the fluid. First results and perspectives are presented in this paper.

We have performed extensive one dimensional particle-in-cell (PIC) simulations to explore generation of electrostatic waves driven by two-stream instability (TSI) that arises due to the interaction between two symmetric counterstreaming electron beams. The electron beams are considered to be cold, collisionless and magnetic-field-free in the presence of neutralizing background of static ions. Here, electrons are described by the non-extensive q-distributions of the Tsallis statistics. Results shows that the electron holes structures are different for various q values such that: (i) for q > 1 cavitation of electron holes are more visible and the excited waves were more strong (ii) for q < 1 the degree of cavitation decreases and for q = 0.5 the holes are not distinguishable. Furthermore, time development of the velocity root-mean-square (VRMS) of electrons for different q-values demonstrate that the maximum energy conversion is increased upon increasing the non-extensivity parameter q up to the values q > 1. The normalized total energy history for a arbitrary entropic index q = 1.5, approves the energy conserving in our PIC simulation.

We report utilization of the laser induced forward transfer technique to re-deposit indium thin films onto the accepter substrate using nJ laser pulses from a femtosecond laser oscillator. Keeping the accepter substrate stationary enables dots of Indium to be deposited; in contrast, linear motion of the accepter substrate facilitates deposition of lines of Indium. The effect of laser pulse energy on the deposition process is studied. The effect of translation speed of donor substrate on the laser induced forward transfer pattern is also probed and an upper limit of translation speed is established beyond which smearing is observed to occur.

Fusion reactions of solid density boron-11 with protons after initiation of a fusion flame by very powerful picosecond laser pulses were derived for plane geometry. The problem of lateral energy losses with laser beams was solved by using spherical geometry, where however the gains are limited. The other elimination of losses now available by cylinder-axis symmetric 10 kilotesla magnetic fields is possible needing laser powers in the exawatt range. Estimations are presented by varying parameters for reducing the necessary laser pulse powers to lower values by up to a factor 100.

A new scheme of particle acceleration is verified by the investigation on single-body dynamics of charged particle in a compound field setup. This compound field setup contains a linear polarized laser field and a DC electric field which is along the direction of laser magnetic field. This setup can cause a charged particle to be of aperiodic motion and significantly high kinetic energy. Moreover, the contribution from the motion vertical to accelerating electric field is fully taken into account and is found to be essential to efficient acceleration. The efficiency of such a setup in acceleration is higher than that of a single laser.

In order to achieve the truncated amplified spontaneous emission pulse, the method of timeshare quenching was proposed in this paper. When the original pulse of the amplified spontaneous emission is 16.72 ns, the obtained best results show that the pulse width is truncated to 2.48 ns, and the shortening ratio is approximately 6.7. By analyzing the 12 acquisition results of the continuous amplified spontaneous emission truncation, 2.59 ± 0.05 ns amplified spontaneous emission pulse was obtained. The experimental results showed that the stability of the truncated pulse width is well. This method is applicable to truncate the ASE pulse in KrF excimer laser. It is significantly to the research of the inertial confinement fusion.

One of the numerous applications of the ICAN laser using the advantage of fiber optics with chirped pulse amplification (CPA), is the scheme of side-on initiation of a nuclear fusion flame in solid density fuel with laser pulses of shorter than picosecond (ps) duration and power in the petawatt (PW) and higher range. The ICAN Fiber optics has special advantages with the potential that >900 PW spherical laser pulses may ignite the proton reaction with 11B (HB11) without the problem of dangerous radioactive radiation. Though secondary reactions can be estimated very roughly, the feasibility of a power station with the necessary energy gains can be concluded.

An ultra-wideband radiation source based on the excitation of a 64-element array of combined antennas by a generator of bipolar voltage pulses with the length of 1 ns, amplitude of 200 kV and pulse repetition rate of 100 Hz has been designed and studied. The peak power of the voltage pulse was 3.2 GW. The effective potential of the ultra-wideband source radiation reached 4.3 MV.

An extended analytical model for particle dynamics in fields of a highly-nonlinear plasma wakefield (the bubble or blow out regime) is derived. A recently proposed piecewise model is generalized to include a time dependent bubble radius and full field solution in the acceleration direction. Incorporation of the cavity dynamics in the model is required to simulate the particle trapping properly. On the other hand, it is shown that the previously reported piecewise model does not reproduce the formation of a mono energetic peak in the particle spectrum. The mono energetic electron beams are recovered only when the full longitudinal field gradient is included in the model.

An optimization scheme for the generation of monoenergetic proton beams by using an overdense hydrocarbon target, followed by an underdense plasma gas, irradiated by an ultra-intense laser pulse is presented. The scheme is based on a combination of a radiation pressure acceleration mechanism and a laser wakefield acceleration mechanism, and is verified by one-dimensional relativistic particle-in-cell (1D PIC) simulations. As compared to the pure hydrogen (H) target, protons in the hydrocarbon target can be pre-accelerated to higher energy and compressed in space due to the existence of the heavy carbon atoms, which provides a better injection process for the successive laser wakefield acceleration in the underdense plasma gas, resulting in the generation of a monoenergetic, tens-of-GeV proton beam. Additionally, for the first time, it is found that the use of the hydrocarbon target can reduce the requirement for laser intensity to generate proton beams with the same energy in this combined scheme, as compared to the use of the pure H target.

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.