With the development of high-power microwave technology, the output power of the pulse generator is required more and more higher. In this paper, it is realized by increasing the output power of the module while the output impedance of the module changes little. The module of the generator is based on pulse forming network (PFN) and linear transformer (LT). Four Blumlein PFNs with arc-type configuration and 24 Ω characteristic impedance were connected symmetrically to the primary coil of the LTD and driven by two identical laser triggered spark switches to ensure four Blumlein PFNs synchronizing operation. On this basis, a two-stage high-power pulse generator based on PFN-LT is developed. The following technical parameters of the generator were achieved on a 12 Ω high-power solid resistor: output voltage amplitude of ∼250 kV and output power of ∼5.2 GW at a repetition rate of 5 Hz.

The third-order nonlinear optical properties of three hydrazone derivatives, namely, ethyl 2-((2E)-2-(4-(dimethylamino)benzylidene]hydrazinyl)-5-nitrobenzoate, ethyl 2-((2E)-2-(4-chlorobenzylidene)hydrazino)-5-nitrobenzoate, and methyl 5-nitro-2-((2E)-2-(4-nitrobenzylidene)hydrazino)benzoate were investigated by the single beam Z-scan technique with nanosecond laser pulses at 532 nm. The compounds were doped into PMMA (poly (methyl methacrylate)), and their third-order nonlinearity was studied with a prospective of reaching a compromise between processability and high nonlinear optical behavior. The optical limiting study of the samples was carried out at 532 nm. The measured values of the third-order nonlinear susceptibility, χ(3), and the nonlinear refractive index, n2, are of the order of 10−13 esu and 10−11 esu, respectively. The nonlinear absorption in materials was attributed to reverse saturable absorption. The results are quite promising for possible applications in photonic devices.

The energy problem is an open issue becoming increasingly pressing. The possibility to use nuclear fusion as an alternative energy source is thus acquiring progressively more importance and many investors are pushing to achieve the goal of an electric plant based on fusion. The most studied reaction is the deuterium-tritium one, but this poses several technical issues related to the handling of the radioactive fuel and neutron generation. In this frame, the aneutronic 11B(p, α)2α fusion reaction has attracted the interest of many researchers. Despite a fusion reactor based on pB is still a long-term goal, the study of this reaction is important both for astrophysics research and for its possible employment in schemes of high brightness source of α particles for applications, as for instance in medicine. Nevertheless, the univocal identification of the produced alphas is a well-known challenging task when the reaction is triggered by high-intensity lasers. Indeed, due to the multifaceted emission typical of laser-matter interactions, the signal coming from alphas is often superimposed to that generated by protons and by other ions, and in many cases, it is therefore hardly recognizable. In this work, we analysed the possibility of employing a Thomson spectrometer (TS) with an adequate differential filtering system for the exclusion from the α-particle trace, the contribution of all other ionic species. Moreover, for the energy ranges where the filtering method cannot be successfully applied, we investigated the feasibility of integrating in the TS assembly a particle detector for time-of-flight (TOF) measurements.

The dynamics of an electron–ion plasma is studied when a mono-energetic relativistic electron beam penetrates the expanding plasma. Combined effects of thermal pressure and ambipolar electrostatic potential are considered for fully relativistic multi-fluids model where the quasi-neutrality assumption is used for a beam–plasma system. Relativistic effects are considered for both density and velocity of the beam fluid. Ion acceleration is depicted through a spike-like structure resulting from non-local charge separation and associated with the beak-down of quasi-neutrality. The beam initial speed is found to enhance the spike amplitude and change its position. Moreover, relativistic effects are particularly found significant for a non-thermal plasma.

Four microseconds long Ar3+ beam with injection energy of 15 keV/u has been injected into the Digital Accelerator of the High-Energy Accelerator Research Organization. Beam production, transportation, and injection are described as well as machine properties. Results of a free running experiment under static magnetic field and longitudinal confinement and acceleration under a fast ramping magnetic field are presented in detail with a brief discussion on the beam lifetime.

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.

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 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.

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 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.

Smoothing of laser-plasma interaction by ISI, RPP, SSD, etc. was mainly directed to overcome lateral nonuniformity of irradiation. While these problems are in no way less important, we derived numerically the model of the Laue rippling and hydrorelaxation model for explanation of the measured temporal pulsation in the 10- to 40-ps range and how the smoothing schemes suppress these pulsations. The partial standing wave fields of the normally coherent laser-irradiated plasma corona is then suppressed by smoothing and conclusion for tests for this model, e.g., by the “question mark experiment” is given. The result provides a physics solution of the laser interaction problem for direct-drive inertial fusion energy

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 acceleration of electrons in a laser plasma at the densities below the critical one is investigated by a particle simulation. It is shown that the stabilization of parametric instability and limitation of the energies of the accelerated electrons take place. The structure of the plasma electron distribution function is examined.

A model for the Stark broadening of ions in a high-density plasma created by laser has been developed by taking account of the full effect of a two-component plasma. One of the objectives of the work was to include the effect of ion dynamics in an efficient way. This has been achieved by using a stochastic process for mixing the different components that constitute a line profile. With the systematic use of fast algorithms, a code has been developed with the ability of treating complex atomic structures.

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.

The main purpose of this work is to describe the construction and operation of the low energy accelerator with energy in the range from (zero to 100 KeV). This accelerator includes an ion source of the cold cathode Penning type (with pierce geometry for ion beam extraction), an accelerating tube (with 8 electrodes) and Faraday cup (FC) for measuring ion current. A vacuum system which gives vacuum of the order 3.0 × 10−8 Torr is used. A palladium tube is used to supply the source with pure hydrogen atoms. It was possible to operate this accelerator with an energy 50 KeV at minimum hydrogen pressure, 6.3 × 10−6 Torr. The total resistance applied between the accelerating electrodes RT = 31.5 MΩ. These data include the influence of the pressure in the accelerating tube, the magnetic field of the ion source, the extraction potential and the accelerating potential on the collector ion current. It was possible to accelerate protons with an energy 50 KeV with current about 100 μA at pressure 6.3 × 10−6 Torr, the source magnetic field = 110 G (IB = 2 A), the arc current = 0.4 A and the extraction potential = 10 KV.

Classical molecular dynamics of the ions and quantum treatment of the electrons are combined in the study of the properties of hot, dense plasmas. An effective ionic interaction potential is used in the molecular dynamics simulations. The electronic density of states is calculated using the equation of motion method. Special attention is given to the broadening of resonances in the electronic density of states, which may have important effects on the thermodynamic properties of the plasma.