2018, 3(6) Column
Matter and Radiation at Extremes 第3卷 第6期
A review of X-pinches of various configurations and of different materials as an X-ray source for various applications is presented. The advantages and disadvantages of different designs of X-pinches as a load for generators with a wide range of output parameters and as a source of X-ray radiation for X-ray point-projection imaging were analyzed.
X-pinch X-ray source X-ray point-projection imaging This paper provides a review of the compact intense electron-beam accelerators (IEBAs) based on liquid pulse forming lines (PFLs) that have been developed at the National University of Defense Technology (NUDT) in China. The history and roadmap of the compact IEBAs used to drive high-power microwave (HPM) devices at NUDT are reviewed. The properties of both de-ionized water and glycerin as energy storage media are presented. Research into the breakdown properties of liquid dielectrics and the desire to maximize energy storage have resulted in the invention of several coaxial PFLs with different electromagnetic structures, which are detailed in this paper. These high energy density liquid PFLs have been used to increase the performance of IEBA subsystems, based on which the SPARK (Single Pulse Accelerator with spark gaps) and HEART (High Energy-density Accelerator with Repetitive Transformer) series of IEBAs were constructed. This paper also discusses how these compact IEBAs have been used to drive typical HPM devices and concludes by summarizing the associated achievements and the conclusions that can be drawn from the results.
High-power microwave (HPM) Intense electron-beam accelerator (IEBA) Pulsed power technology (PPT) Pulse forming line (PFL) Fluid of high energy density De-ionized water Glycerin In this work, characteristics of X/γ-ray radiations by intense laser interactions with high-Z solids are investigated by means of a newly developed particle-in-cell (PIC) simulation code. The PIC code takes advantage of the recently developed ionization and collision dynamics models, which make it possible to model different types of materials based on their intrinsic atomic properties. Within the simulations, both bremsstrahlung and nonlinear Compton scatterings have been included. Different target materials and laser intensities are considered for studying the parameter-dependent features of X/γ-ray radiations. The relative strength and angular distributions of X/γ ray productions from bremsstrahlung and nonlinear Compton scatterings are compared to each other. The threshold under which the nonlinear Compton scatterings become dominant over bremsstrahlung is also outlined.
Particle-in-cell simulations Bremsstrahlung Nonlinear Compton scattering Laser-solid interactions The spectral line intensities and line shifts of Lyman and Balmer series for transitions up to n = 5 of hydrogen-like ion are studied in plasmas with densities and temperatures in the ranges ne ~1018-1021 cm-3, Te = 0.3-1.2 eV respectively. The screened potential used to describe the interaction between charged particles includes the electron exchange-correlation and finite-temperature gradient effects and is valid for both weakly and strongly coupled plasmas. The dependencies of alpha, beta and gamma line shifts of Lyman and Balmer series on plasma density (for fixed temperature) and temperature (for fixed density) are investigated. The results for the Ha line shifts are compared with the available highdensity experimental data.
Screened coulomb interaction Hydrogen-like ion Spectral lines High density plasmas Targets for low-adiabat direct-drive-implosion experiments on OMEGA must meet rigorous specifications and tight tolerances on the diameter, wall thickness, wall-thickness uniformity, and presence of surface features. Of these, restrictions on the size and number of defects (bumps and depressions) on the surface are the most challenging. The properties of targets that are made using vapor-deposition and solutionbased microencapsulation techniques are reviewed. Targets were characterized using confocal microscopy, bright- and dark-field microscopy, atomic force microscopy, electron microscopy, and interferometry. Each technique has merits and limitations, and a combination of these techniques is necessary to adequately characterize a target. The main limitation with the glow-discharge polymerization (GDP) method for making targets is that it produces hundreds of domes with a lateral dimension of 0.7-2 mm. Polishing these targets reduces the size of some but not all domes, but it adds scratches and grooves to the surface. Solution-made polystyrene shells lack the dome features of GDP targets but have hundreds of submicrometer-size voids throughout the wall of the target; a few of these voids can be as large as ~12 mm at the surface.
Vapor-deposition Direct-drive target OMEGA Target characterization Solution-based microencapsulation 公告
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