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.

We present the experimental optimization of electrons in the several hundred keV energy range originated from laser-irradiated wire targets. Accelerated by a femtosecond laser pulse, an electron pulse emitted from the wire target was collimated immediately along the wire to a filter unit for the manipulation of energy and spatial distributions. It is shown in simulation that with a pair of magnets as the filter unit, the optimized electrons could serve as a compact and tunable electron source. The proposed system was demonstrated in a proof-of-principle experiment where we attained 1 fC bunch charge with transverse coherence length approaching 1 nm based on a 0.2 TW laser platform. This indicates the scheme as a promising candidate for single-shot electron diffraction.

In doing research on the turbulent mixing (TM) of two gases different in density, it is of great interest to study experimentally the 3D density distribution pattern of chemically nonreactive gases in the TM zone. For this purpose, noncontact and, particularly, optical techniques to obtain experimental data may be attractive. This article discusses the possibility of using pulsed laser interferometry in this application. Based on this technique, the experiment should result in the mixture density distribution integrated along the light path. Requirements for high-quality interference patterns have been analyzed in application to typical experimental conditions, to show that they may be produced with specific restrictions set on the mixture constitution. Generally, the TM zone has no symmetry. Therefore, the problem of reconstructing 3D density distributions (TDD) of gases can be solved by sufficiently providing many TM zone integral projections (or aspects). It is technically difficult and expensive to achieve this large number of aspects (N> 10). Therefore, it is essential that a reconstruction method be selected to allow the solution of the problem with the least possible number of aspects. Given that the experiment data are incomplete, the reconstruction methods that are based on the concept of maximum data entropy did well. Information a priori about the solution to be sought for an isobaric gas mixture is that its each constituent has invariable density. Thus, a functional data entropy can be defined that is similar to Fermi gas in statistical physics. An algorithm has been suggested for reconstruction as a modified maximum-bounded entropy procedure (Bashurin et al. 1995). This makes reasonable good reconstruction achievable even with as few aspects as N = 4. Experiments on the study of TM of a propane jet in air using a four-aspects laser interferometer were provided and reconstruction of propane concentration distribution was conducted. The results allow determination of the TM zone spectral characteristics.

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.

Temporal evolution of X-ray spectra of lead plasma produced by a CO2 laser pulse with energy of 100 J and a duration of 15 ns has been measured using a six-channel X-ray polychromator. The polychromator registered the radiation intensity in the range from 180 to 1850 eV. Plasma temperature was determined by comparison of measured results with radiation spectra obtained by numerical simulation. The values of electron temperature are in good agreement with results of hydro simulations.

The paper presents the results of calculation and optimization of a structure of a radial insulating magnetic field in an acceleration gap of a high-power ion diode. A diode configuration with an induction plasma source and an anode configuration with azimuthally symmetrical slots and a pair of cathode coils of a magnetic diode system have been studied. When the size of the slots is ≤5 mm and codirectional magnetic fields of a diode and shock induction coil, the perturbation of the B-field does not exceed ≤20% and is located in the region near the anode. In this condition, the topology of the magnetic field В = f(1/r) is maintained in the acceleration gap. It was shown that the required radial distribution of the B-field can be optimized by varying the anode profile in the region opposite to two cathode coils of the diode magnetic system.

In this work, we studied the photon emission in the visible light range for Xeq+ ions of different charge states (10 ≤ q ≤ 21) bombardment on an aluminum target at 410 keV. During the interactions, the spectra in wavelength range 300–500 nm are recorded, including the photons from Al atoms and neutralized Xe+ ions. The yield of the visible light strongly depends on the projectile charge states. Its variation tendency with the charge states is similar to that of the potential energy variation. In addition, the experimental results also indicate that when the incident charge state is less than the critical charge state, it obeys the staircase classical-over-barrier model.

Far-field images produced using different random phase plates on a pulsed laser beam focused with variousf/numbers were recorded by a charge-coupled device (CCD) camera and then analyzed. Envelope spot sizes agree with diffraction theory while mean sizes of the pattern structures have been found to be larger than the diffraction limit. The probability density distribution of intensity in the focal plane is not the expected exponential. A central symmetry of the pattern has also been seen after suitably aperturing the beam. Some consequences for the use of powerful RPP-treated laser beams in laser-plasma interactions are discussed.

A vertical dispersion variant of the Johann spectrometer has been used to record the highresolution X-ray spectra of the chlorine He-like resonance line group emitted from lowradiance plasma. The emission profiles were measured at two observation angles and decomposed into single spectral lines by using a fit based on the Levenberg-Marquardt algorithm. The results of computerized analysis of the one-dimensional (1-D) spatially resolved spectra were used to evaluate the distribution of the main plasma parameters. The electron temperature gradient 7.5·104 eV cm-1 was computed by modeling the measured spectra with the collisional-radiative package RATION. The blowoff maximum velocities 4.2–6.1·107 cm s-1 and the velocity gradients 0.9–1.6·109 s-1 were determined from the Doppler shifts of individual spectral lines within their different spatial extent.

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

A computer model has been developed and benchmarked for the nuclear-pumped atomic carbon laser. Experiments have been performed with the atomic carbon laser and with the radiolysis of CO2 as a benchmark for the model. The results of the CO2 radiolysis are described.

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.

When a heavy ion beam passes through a plasma in reactor chamber, it scatters some plasma electrons in the direction perpendicular to that of beam propagation. The presence of such electrons causes an instability to deflect the beam from the target pellet. The instability is analyzed by coupled equations for density and temperature for the electrons, and numerical results are given.

Compton scattering of laser light by an electron beam at large angles, in particular at 90°, produces coherent hard radiation if the density of the electron beam is high enough. In this case, the intensity of the scattered radiation is greatly enhanced in a small cone around the forward direction of propagation of the electron beam. As an example, the production of 1-KeV coherent X rays is discussed.

In order to minimize the initial energy storage of tens of MA-class Z-pinch accelerators, an intelligent optimization method was developed based on the transmission line code circuit model and PSOGSA algorithm. Using several input parameters, the four overall parameters of the Z-pinch accelerator could be fast determined, including the connection and parallel combination of LTD cavities, the outer radius of the stack-MITL system, and electrical length of monolithic radial transmission lines. The optimization method has been verified by comparing the results with the Z-300 and Z-800 conceptual designs. By means of this intelligent optimization, some factors that affect the initial energy storage on high-current Z-pinch accelerators have been investigated, such as the operating electrical fields, the diameter of the stack-MITL system, and the inner diameter of the LTD cavity. The suggestions for designing relatively low-cost, efficient LTD-based accelerators have been proposed.