In this paper, the intense laser heating of hydrogen pair-ion plasma with and without electron impurities through investigation of related nonlinear phenomena has been studied in detail, using a developed relativistic particle-in-cell simulation code. It is shown that the presence of electron impurities has an essential role in the behavior of nonlinear phenomena contributing to the laser absorption including phase mixing, wave breaking, and stimulated scatterings. The inclusion of electron into an initial pure hydrogen plasma not only causes the occurrence of stimulated scattering considerably but also leads to the faster phase-mixing and wave breaking of the excited electrostatic modes in the system. These nonlinear phenomena increase the laser absorption rate in several orders of magnitude via inclusion of the electrons into a pure hydrogen pair-ion plasma. Moreover, results show that the electrons involved in enough low-density hydrogen pair-ion plasma can be accelerated to the MeV energy range.

The quantum behavior of the system composed of an electron in an electromagnetic field is described by the Dirac equation, whose solution is a wave function represented by a column matrix with four components. We prove, without using any approximation, that these components can be put in a form which reveals directly the values of the electron energy, laser beam intensity, or amplitude of the electric field intensity, for which the quantum electrodynamics effects are generated. Our results are in good agreement with the experimental data reported in the literature. We prove that the four components of the wave function verify the continuity equation of quantum electrodynamics. Our treatment is in good agreement with the Compton relation. We show that the interaction of electrons with laser beams could be modeled using classical approaches regardless of the laser beam intensity as long as the electrons are non-relativistic, in agreement with published experimental data.

By sophisticated application of particle-in-cell simulations, we demonstrate the ultimate role of non-linear pulse evolutions in accelerating electrons during the entrance of an intense laser pulse into a preformed density profile. As a key point in our discussions, the non-linear pulse evolutions are found to be very fast even at very low plasma densities, provided that the pulse length exceeds the local plasma wavelength. Therefore, these evolutions are sufficiently developed during the propagation of typical short density scale lengths occurred at high contrast ratios of the pulse, and lead to plasma heating via stochastic acceleration in multi-waves. Further analysis of simulation data at different physical parameters indicates that the rate of evolutions increases with the plasma density leading to higher plasma heating and overgrown energetic electrons. In the same way, shortening the density scale length results into increase in the evolution rate and, simultaneously, decrease in the interaction time. This behavior can describe the observed optimum value of pre-plasma scale length for the maximum electron heating.

The paper presents the results of a study on propagation and focusing of high-intensity pulsed ion beams, produced by a self-magnetically insulated diode of semi-cylindrical geometry at the TEMP-6 accelerator (120 ns, 200–250 kV). We examined the space-charge neutralization of the beam, the energy density in the focus, the divergence of the beam, and its shot-to-shot displacement in the focal plane. It is found that the concentration of low-energy electrons in the beam is 1.3–1.5 times higher than the concentration of ions. We observed additional ion focusing by its own space charge. With an increase in the density of the net negative (electrons and ions) charge of the beam from 3.6 to 9 µC/cm2, the total divergence (the sum of the beam divergence in the vertical and horizontal planes) decreases from 11.4 to 4.5°. It leads to an increase in the energy density in the focus from 4 up to 10–12 J/cm2. To increase the electrons concentration in the beam, a metal grid installed in the ion beam transport region was used.

The experimental study of the plasma projectile acceleration in the laser-induced cavity pressure acceleration (LICPA) scheme is reported. In the experiment performed at the kilojoule PALS laser facility, the parameters of the projectile were measured using interferometry, a streak camera and ion diagnostics, and the measurements were supported by two-dimensional hydrodynamic simulations. It is shown that in the LICPA accelerator with a 200-J laser driver, a 4-μg gold plasma projectile is accelerated to the velocity of 140 km/s with the energetic acceleration efficiency of 15–19% which is significantly higher than those achieved with the commonly used ablative acceleration and the highest among the ones measured so far for any projectiles accelerated to the velocities ≥100 km/s. This achievement opens the possibility of creation and investigation of high-energy-density matter states with the use of moderate-energy lasers and may also have an impact on the development of the impact ignition approach to inertial confinement fusion.

Three triode extraction systems are simulated by IBSimu ion optical code for Amirkabir Helicon Ion Source (AHIS). The optimized pierce and suggested parabolic electrodes are introduced for the first time in this paper. The obtained N+ beam for parabolic geometry designed for ion implantation has 66 keV energy, and 10.4 mA current. Ion beam emittance and Twiss parameters of the emittance ellipse as the function of x term index are calculated for parabolic electrode equation. The simulated triode extraction systems have been evaluated by using of optimized parameters such as the extraction voltage, gap distance, plasma electrode (PE) aperture, and ion temperature. The extraction voltage, gap distance, PE aperture, and ion temperature have been changed in the range of 58–70 kV, 35–39 mm, 4–6 mm, and 0.5–4.4 eV in the simulations, respectively.

The paper describes a technique for operative control of the high-intensity pulsed ion beam parameters. The time-of-flight diagnostics uses one high-speed Faraday cup sensor with magnetic cut-off of low-energy electrons. The technique makes it possible to determine the composition of the beam (the type of ions and the degree of ionization), the absolute values of the current density of ions and the energy spectrum for each type of ions with an error of <±10%. The technique was tested at different pulsed ion accelerators and ion diodes both with self-magnetic insulation (accelerating voltage of 200–250 kV, ion current density of 20–300 A/cm2) and external magnetic insulation of the electrons (400–500 kV, 200 A/cm2). The article presents a comparative analysis of two types of Faraday cups with magnetic cut-off of the electrons and with electric bias.

After achieving significant research results on laser-driven boron fusion, the essential facts are presented how the classical very low-energy gains of the initially known thermal ignition conditions for fusion of hydrogen (H) with the boron isotope 11 (HB11 fusion) were bridged by nine orders of magnitudes in agreement with experiments. This is possible under extreme non-thermal equilibrium conditions for ignition by >10 PW-ps laser pulses of extreme power and nonlinear conditions. This low-temperature clean and low-cost fusion energy generation is in crucial contrast to local thermal equilibrium conditions with the advantage to avoid the difficulties of the usual problems with extremely high temperatures.

This paper presents an investigation on the self-focusing of a cosh-Gaussian laser beam in the thermal quantum plasma (TQP) by taking into account the effects of relativistic nonlinearity. An appropriate nonlinear Schrödinger equation has been solved analytically by applying the variational approach. The self-focusing and the self-phase modulation are examined under a variety of parameters. The self-trapping of a cosh-Gaussian laser beam is further studied at various values of the decentered parameter, b with different absorption levels, ${k}^{\prime}_i$. Numerical analysis shows that these parameters play a vital role in propagation characteristics. The significant contribution of the quantum effects to enhance the self-focusing and minimize the longitudinal phase has been observed. Further, a comparison has been made with the classical relativistic (CR), the relativistic cold quantum (RCQ), and the thermal quantum (TQ) regimes. The self-focusing is found to occur earlier and is strongest for the case of TQP in the present analysis.

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.

In order to diminish the occurrence of cavitation bubbles during the liquid-assisted laser machining, ultrasound-assisted underwater femtosecond laser drilling on stainless steel is adopted. This method greatly diminishes the optical disturbance of cavitation bubbles. By investigating and analyzing the effect of laser pulse energy and pulse number on the morphology of the holes, it has been found that ultrasound not only has a remarkable function of forming a hole with clean and flat bottom, but also reduces debris redeposition around the processing area. This method improves the machining quality. Besides, it also improves the depth-to-diameter ratio of the hole about 20%.

Krypton Large Impulse Thruster (KLIMT) project was aimed at incremental development and optimization of a 0.5 kW-class plasma Hall Effect Thruster in which, as a propellant, krypton could be used. The final thermally stable version of the thruster (the third one) was tested in the Plasma Propulsion Satellites (PlaNS) laboratory in the Institute of Plasma Physics and Laser Microfusion (IPPLM) in Warsaw as well as in the European Space Agency (ESA) propulsion laboratory in the European Space Research and Technology Centre (ESTEC).

During final measurement campaign, a wide spectrum of parameters was tested. The plasma potential, electron temperature, electron concentration, and electron energy probability function in the far-field plume of the thruster were measured with a single cylindrical Langmuir probe. Faraday probes were used for recording local values of ion current. Using several collectors in different locations and moving them on the surface of a sphere, the angular distribution of the expelled particles was reconstructed which was a local measure of beam divergence. Angular distribution of ion flux as measured with a central Faraday probe was parameterized with krypton mass flow rate, voltage, coil current ratio, and the cathode mass flow rate. Beam divergence measurements with Faraday probes as well as plasma parameters derived from Langmuir probe seem to be consistent with our understanding of the operating envelope. Obtained results will serve as a baseline in the design of plasma beam structure diagnostics system for the PlaNS laboratory.

In inertial confinement fusion experiments that involve short-laser pulses such as fast ignition (FI), diagnosis of neutrons is usually very challenging because high-intensity γ rays generated by short-laser pulses would mask the much weaker neutron signal. In this paper, fast-response scintillators with low afterglow and gated microchannel plate photomultiplier tubes are combined to build neutron time-of-flight (nTOF) spectrometers for such experiments. Direct-drive implosion experiments of deuterium-gas-filled capsules were performed at the Shenguang-II Upgrade (SG-II-UP) laser facility to study the compressed fuel areal density (〈ρR〉) and evaluate the performance of such nTOF diagnostics. Two newly developed quenched liquid scintillator detectors and a gated ultrafast plastic scintillator detector were used to measure the secondary DT neutrons and primary DD neutrons, respectively. The secondary neutron signals were clearly discriminated from the γ rays from (n, γ) reactions, and the compressed fuel areal density obtained with the yield-ratio method agrees well with the simulations. Additionally, a small scintillator decay tail and a clear DD neutron signal were observed in an integrated FI experiment as a result of the low afterglow of the oxygen-quenched liquid scintillator.

In the present paper, we have investigated self-focusing of the quadruple Gaussian laser beam in underdense cold quantum plasma. The non-linearity chosen is associated with the relativistic mass effect that arises due to quiver motion of electron and electron density perturbation caused by ponderomotive force. The non-linearity modifies the plasma frequency in the dielectric function and hence the refractive index of the medium. The focusing/defocusing of the quadruple laser depends on the refractive index of the medium. We have set up non-linear differential equation that controls the beam width parameter by using well-known paraxial ray approximation and Wentzel–Krammers–Brillouin approximation. The effect of intensity parameter and electron temperature is observed on laser beam self-focusing in the presence of cold quantum plasma. From the results, it is revealed that electron temperature and the initial intensity of the laser beam control the profile dynamics of the laser beam.

The effect of two intense cross-focused cosh-Gaussian laser (CGL) beams on the generation of electron plasma wave (EPW) and particle acceleration in collisionless plasma has been investigated under the relativistic–ponderomotive regime. Due to mutual interaction of two laser beams, cross-focusing takes place in plasma. The EPW is generated by the beating of two cross-focused CGL beams of frequencies ω1 and ω2. An analytical expression for the beamwidth of laser beams and EPW as well as the power of the generated EPW has been evaluated using Wentzel–Kramers–Brillouin and paraxial approximations. The energy of the accelerated electrons by the beat-wave process has also been calculated. Numerical simulations have been carried out to investigate the effect of typical laser plasma parameters on the power of excited EPW and acceleration of electrons. The results are compared with only relativistic nonlinearity and the Gaussian profile of laser beams. It is observed that CGL beams focused earlier than Gaussian beams, which significantly affected the dynamics of plasma wave excitation and particle acceleration. Numerical results indicate that there is a remarkable change in the power of generated EPW and electron acceleration in the relativistic–ponderomotive case in comparison with only relativistic case.

In the interaction of short-laser pulses with a solid density target, pre-plasma can play a major role in ion acceleration processes. So far, complete analysis of pre-plasma effect on the ion acceleration by ultra-short laser pulses in the radiation pressure acceleration (RPA) regime has been unknown. Then the effect of pre-plasma on the ion acceleration efficiency is analyzed by numerical results of the particle-in-cell simulation in the RPA regime. It is shown that, for long-laser pulses (τp > 50 fs), the presence of pre-plasma makes a destructive effect on ion acceleration while it may have a contributing effect for short-laser pulses (τp < 50 fs). Therefore, the 35 fs (20 fs) laser pulse can accelerate ions up to 40 MeV (55 eV), which is almost two (three) times larger in energy rather than use of a 100 fs pulse with the same pre-plasma scale length.

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.

A coaxial-output rolled strip pulse-forming line (RSPFL) with a dry structure is researched for the purpose of miniaturization and all-solid state of pulse-forming lines (PFL). The coaxial-output RSPFL consists of a coaxial-output electrode (COE) and a rolled strip line (RSL). The COE is characterized by quasi-coaxial structure, making the output pulse propagate along the axial direction with a small output inductance. The RSL is rolled on the COE, whose transmission characteristics are analyzed theoretically. It shows that the RSL can be regarded as a planar strip line when the rolling radius of the strip line is larger than 60 times of the thickness of the insulation dielectric layer of RSL. CST modeling was carried out to simulate the discharging characteristic of the coaxial-output RSPFL. It shows that the coaxial-output RSPFL can deliver a discharging pulse with a rise time <6 ns when the impedance of the RSL matches that of the COE, which confirms the theoretical analysis. A prototype of the coaxial-output RSPFL was developed. A 49-kV discharging pulse on a matched load was achieved when it was charged to 100 kV. The discharging waveform has a pulse width of 32 ns, with a rise time of 6 ns, which is consistent with the simulation waveform. An energy-storage density of 1.9 J/L was realized in the coaxial-output RSPFL. By the method of multi-stage connection in series, a much higher output voltage is convenient to be obtained.

The fractures of a soda-lime glass surface layer were investigated under irradiation by a high-power ion beam of nanosecond duration with different current densities. Two kinds of cracks (perpendicular and approximately parallel irradiated surfaces) have been identified. It is defined that cracks approximately parallel to the surface are localized at a depth of 10 ± 2 µm from the irradiated glass surface after one-time irradiation with a current density of 100 A/cm2. The formation of these cracks was detected within ~170 h after the end of irradiation when irradiated samples were under an air atmosphere. In a vacuum, the growth of these cracks was insignificant. It is shown that irradiation of heated glass or heating of glass started no later than 2–3 min after irradiation can suppress or substantially reduce surface fracture of glass. The possible mechanisms of glass fracture were discussed.

Laser-based compact MeV X-ray sources are useful for a variety of applications such as radiography and active interrogation of nuclear materials. MeV X rays are typically generated by impinging the intense laser onto ~mm-thick high-Z foil. Here, we have characterized such a MeV X-ray source from 120 TW (80 J, 650 fs) laser interaction with a 1 mm-thick tantalum foil. Our measurements show X-ray temperature of 2.5 MeV, flux of 3 × 1012 photons/sr/shot, beam divergence of ~0.1 sr, conversion efficiency of ~1%, that is, ~1 J of MeV X rays out of 80 J incident laser, and source size of 80 m. Our measurement also shows that MeV X-ray yield and temperature is largely insensitive to nanosecond laser contrasts up to 10−5. Also, preliminary measurements of similar MeV X-ray source using a double-foil scheme, where the laser-driven hot electrons from a thin foil undergoing relativistic transparency impinging onto a second high-Z converter foil separated by 50–400 m, show MeV X-ray yield more than an order of magnitude lower compared with the single-foil results.