A linearly polarized laser pulse has been employed as a wiggler in a free-electron laser (FEL) in the presence of a plasma background for generating short wavelength radiation down to the extreme ultraviolet ray and X-ray spectral regions. Introducing plasma background in the FEL interaction region would lessen the beam energy requirement and also enhance both the beam current and the electron-bunching process. This configuration affords the possibility of scaling the device to more compact FELs and would have a higher tunability by changing the plasma density and the temperature of the electron beam. Electron trajectories have been analyzed using single-particle dynamics. The effect of plasma density on electron orbits has been investigated. A polynomial dispersion relation considering longitudinal thermal motion has been derived, by employing perturbation analysis. Numerical studies indicate that by increasing plasma density, the growth rate for groups I and II decreases, while the growth rate for group III increases. In addition, the effect of beam temperature and cyclotron frequency on the growth rate has been discussed. It has been found that by increasing the thermal velocity of the electron beam, the growth rate for groups I and III trivially decreases, while it increases for group II orbits. Besides, an increase in cyclotron frequency cause growth enhancement for group I orbits, while it present a growth decrement for group II and III orbits.

A study of ASP 30 steel surface modification with high intensity Ti:sapphire laser, operating at 804 nm wavelength and pulse duration of 60 fs, in vacuum ambient, is presented. ASP 30 steel surface variations were studied at laser intensities of 1014 and 1013 W/cm2. The steel target specific surface changes and phenomena observed are: (i) Creation of craters at 1014 W/cm2 intensity; (ii) formation of periodic surface structures only at the reduced intensity of 1013 W/cm2; (iii) chemical surface changes registered only at higher laser intensity, and (iv) occurrence of plasma in front of the surface, including its emission in X-ray region. It can be concluded from this study that the reported laser intensities can effectively be applied for ASP 30 steel surface modification. Careful choosing of laser intensity and pulse count can lead to precise superficial material removal, for example laser intensity ~1013 W/cm2 and low pulse count can lead to ultra-precise surface processing. Generally, femtosecond laser surface modification of ASP 30 steel is non-contact and very rapid compared with traditional modification methods.

The charge state and the level populations of ionic projectiles that are stopped in hydrogen plasma are calculated in the average ion model. It is shown that in available experimental systems the parameters can be chosen such that the end of the range will occur inside the plasma column. The predicted narrow region over which recombination occurs can be used as a check on plasma stopping-power theory and as a direct measurement of the range, using spectroscopic diagnostics.

The generation of coherent soft X rays is studied using a terawatt picosecond Nd:glass laser system. Two different methods are investigated as candidates for efficient generation of such radiation, namely, longitudinally pumped transient collisional excitation nickel-like molybdenum X-ray laser, and high-harmonic generation from solid–vacuum interfaces. In the course of experiments on longitudinally pumped X-ray lasers, unexpected jetlike structures are observed in the visible emission of the molybdenum plasma, extending over a length of several millimeters. An interesting characteristic of this phenomena is that clear jets are observed only for longitudinal pump intensities between 5 × 1014 and 7 × 1014 W/cm2. The effects of a finite scale length density gradient on surface harmonics is also investigated. The efficiency of harmonic generation from near-solid density plasma is found to increase by a factor of 2 to 3 when using prepulses. The scale length of the preplasma is simulated using a one-dimensional hydrodynamic code, and the increase in efficiency is verified to be in accordance with particle-in-cell simulation results.

A spherical scheme is introduced for indirect drive, having as reference the application to inertial fusion energy. The concept uses the transmission of a radiation wave through a high-Z, low-density spherical radiator surrounding the capsule to be imploded. The low conversion efficiency to in-cavity radiation is somewhat compensated by using modest radiator-to-capsule gaps, the smoothing effects on the longest dominant nonuniformity wavelengths due to this separation being of the order of 10. Another factor of the order of 100–500 is related to the consequent use of a large number of beams. From the application of the loop condition relative to power plants, it is found that this approacrTbecomes practicable if drivers with efficiencies greater than 10% are assumed and if the fraction of circulating power is allowed to be 0.5, this implying a unitary cost of energy about a factor 1.5 greater than that associated to the more conventional fraction of 0.25.

Medium-mass ion beams including nitrogen and oxygen were produced from a cryogenic diode with N2O ice as the ion source. The nominal diode voltage was 300–400 kV, and the peak ion current was 240 A. The beam divergence angle was measured with a five-aperture time-integrated pinhole camera. The five camera images were analyzed to estimate the spatial distribution of the beam source divergence angle along the anode radius, yielding a value of 5–6 mrad for the average microdivergence. This is low enough for this ion source to be studied further in the near future. If possible, we want to consider this as one of the probable candidate ion sources for ion beam drivers for future inertial confinement fusion (ICF) and inertial fusion energy (IFE) applications.

Under certain restrictions imposed on the plasma parameters, an analytical 2D solution to the magnetohydrodynamic equations, taking into account the Hall effect [of the HMHD (Hall magnetohydrodynamic) equations], is found for the case when plasma flows across a magnetic field. This solution has the form of the sum of a rather arbitrary steady flow and a small time-dependent disturbance. We show that waves of a purely acoustic nature can propagate against the background of the flow. The magnetic field manifests itself in this process only in that it produces an effective gravity force, the “gravitational” acceleration being proportional ωeτe. Like acoustic-gravity waves in the atmosphere, such quasiacoustic-gravity (QAG) waves in a plasma increase greatly in their amplitude as they propagate “upward,” that is, in this case, to the anode of an accelerating plasma channel. The existence of a rather general dimensionless similarity criterion is also shown. It can be found directly from the structure of the HMHD equations without any restrictions as to the plasma parameters.

Thermal imaging diagnostics was used as a surface temperature mapping tool to characterize the energy density distribution of a high-intensity pulsed ion beam. This approach was tested on the TEMP-6 accelerator (200–250 kV, 150 ns). The beam composition included carbon ions (85%) and protons, and the energy density in the focus was 5–12 J/cm2. Targets of stainless steel, titanium, brass, copper, and tungsten were examined. Our observations show that the maximum energy density measured with the thermal imaging diagnostics considerably exceeds the ablation threshold of the targets. An analysis of the overheating mechanisms of each target was carried out, including metastable overheating of the target to above its boiling temperature during rapid heating; formation, migration, and the subsequent annealing of fast radiation-induced defects in the target under ion beam irradiation. This expands the range of energy density measurement for this thermal imaging diagnostics from 2–3 J/cm2 up to 10–12 J/cm2 but introduces error into the results of measurement. For a stainless steel target, this error exceeds 15% at an energy density of more than 4 J/cm2. A method of correcting the results of the thermal imaging diagnostics is developed for a pulsed ion beam under conditions of intense ablation of the target material.

Plasma wakefield excited by a short TeV-scale proton beam is investigated in the highly nonlinear regime. Analysis of the “bubble” field illustrates that transverse expelling force of the wakefield can be compensated by the attractive force, which originates from the co-propagating electrons within the proton bunch, leading to a collimation effect that stabilizes the beam propagation. The protons located in the beam tail can be well-confined and accelerated forward for a long distance. Two-dimensional simulations show that after a 1-TeV proton bunch propagating through plasma for a distance, several percentages of the protons achieve a remarkable energy gain. This scheme presents a potential that proton beams from conventional accelerators may gain considerable additional energy through plasmas wakefields.

Three gas lenses appear promising for fusion and other applications. We review progress of the understanding and scaling of two of these lenses and discuss their potential for industry, advanced research, and fusion.

Interaction of extreme ultraviolet (EUV) pulses of high intensity with gases results in the creation of non-thermalized plasmas. Energies of the driving photons and photoelectrons are sufficient for creation of excited states, followed by emission of the EUV photons. In most cases, decay times of these states are short comparing to the driving EUV pulse. It means that just after stopping of the driving pulse, the EUV emission corresponding to the excited states should also stop. From our earlier measurements in the optical range, however, it can be concluded that lifetimes of such plasmas exceed a time duration of the driving pulse even two orders of magnitude. Hence, it can be expected that the time duration of the EUV emission can be also significantly longer than the irradiation time. In this work, EUV-induced, low-temperature helium (He), krypton, and xenon plasmas were investigated. EUV emission from these plasmas was studied, using a specially prepared detection system, allowing for time-resolved measurements, in selected spectral ranges. The detection system was based on a paraboloidal collector and a semiconductor photodiode, sensitive for the EUV photons. For spectral selection, the corresponding filters or multilayer mirrors were employed. In most cases, the time duration of the EUV emission was significantly longer than the driving EUV pulse. In case of He plasmas, the emission corresponding to excited atoms was detected even hundreds of nanoseconds after the irradiation. It was also shown that the corresponding time profiles depended on densities of gases to be ionized.

It is shown that there is a principal possibility of effective burning with gain G > 200 of ecologically clean DHe3 fuel in reactor-type targets without increase of driver energy. The proper target consists of DHe3 fuel and a D-T ignitor with a central hot spark. Under proper conditions, the D-T burning wave reaches the DHe3 range with the temperature sufficient for ignition of DHe3 plasma. The simulation was carried out by means of TERA code based upon self-consistent solution of a kinetic equations system for products of primary and secondary thermonuclear reactions by the Monte Carlo method and a hydrodynamic equations system.

The work proposes a straightforward method for determining the nuclear reaction cross sections at extremely low energies (E ≃ 1–100 keV) on the basis of the measurements of the relative yield of fast particles which are products of the nuclear reactions in a target under laser compression. On the other hand, the proposed method makes it possible to find the averaged form of the ion velocity distribution function if the low-energy behaviour of the respective cross sections is known.

This issue of Laser and Particle Beams includes papers presented at the Workshop on “Fast High Density Plasma Blocks Driven by Picosecond Terawatt Lasers” held at the University of Western Sydney, Campbelltown Campus, Australia from 1–4 December 2004.

In this paper, conceptual points regarding electron elastic (Kapitza–Dirac effect) and inelastic diffraction effects on the slowed electromagnetic wave-structures/light-gratings are considered. From the unified point of view it is analyzed the main works on this subject for last four decades in chronological order, pointing out the essential peculiarity inherent in induced Cherenkov, Compton, and undulator/wiggler processes too. This review paper has also purpose to resolve confusion in scientific literature connected with the recently appeared paper Hayrapetyan et al. in 2015 regarding electron diffraction effect on a traveling wave in a dielectric medium.

It is my pleasure to present the Special Issue of Laser and Particle Beams devoted to the 25th anniversary of the Institute of High Current Electronics (IHCE) of the Russian Academy of Sciences Siberian Division.

The present review is of the experimental investigations on laser-plasma interaction being carried out in past years at IAE. Experiments were conducted on the “Mishen” facility. The laser system of Mishen consists of two channels with output beam parameters as follows: the main beam—output energy 100–200 J (λ = 1.054 μm) in 3-ns pulse, divergence ∼2 × 10-4 rad, contrast ratio ∼106, power density at the target surface ∼1013–1014 W/cm2; the diagnostic beam–output energy 10–20 J (λ = 1.054 μm) and 5–10 J (λ = 0.53 μm) in 0.3-ns pulse, divergence ∼10-4 rad, power density 1013 - 1014 W/cm2. Our aim in this experiment is to study the different aspects of the ICF processes in flat geometry. The main issues of our studies are hydrodynamic aspects, including acceleration efficiency, high-velocity impact in cascade targets, hydrostability, and X-ray physicsconversion efficiency, heat transfer, and X-ray-driven targets.

Electrical quasi-neutrality is not a general property of a thermalized self-gravitating plasma. If the massive component of a two-component plasma consists of charged macroscopic solid grains for which the charge-to-mass ratio is of order then self-gravitation and thermalization lead to substantial large-scale charge separation. An alternative statement of the condition for substantial equilibrium charge separation is that the Jeans length and Debye length of the plasma are similar.

We consider a system of condensations in such a plasma and show that properties of the system are similar to observed properties of the system of galaxies.

A novel idea is presented in this paper to simulation, design, and feasibility of making a machine in order to produce nitrogen 13 (N-13) at a much lower cost than conventional medical applications. In a plasma focus device, only 0.02% of the generated ions have more than 1 MeV energy. In this paper, using a new idea we have tried to find a solution to increase the energy of deuterium ions to produce N-13. To achieve this, a series of magnetic lenses has been used to focus and guide the ions. To increase the ion energy, a small linear accelerator has been designed using a TM010 waveguide. The accelerator waveguide is also designed and optimized to have the highest impedance matching and maximum power transmission. Eventually, low-energy ions that are transmitted by magnetic lenses accelerate in the waveguide electric field and their energy increases significantly. The collision of these energetic ions with graphite target produce N-13.