Guiding of relativistically intense laser pulses with peak power of 0.85 PW over 15 diffraction lengths was demonstrated by increasing the focusing strength of a capillary discharge waveguide using ...laser inverse bremsstrahlung heating. This allowed for the production of electron beams with quasimonoenergetic peaks up to 7.8 GeV, double the energy that was previously demonstrated. Charge was 5 pC at 7.8 GeV and up to 62 pC in 6 GeV peaks, and typical beam divergence was 0.2 mrad.
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We consider the results of computational experiments concerning the expansion of a plasma generated by laser radiation at the stage of a nanosecond prepulse ahead of the main femtosecond-range pulse. ...A series of plasmodynamic calculations are performed for various laser target materials. It is shown that in the considered problem statement, which corresponds to the typical conditions of full-scale experiments, the distribution of the laser plasma density as a whole is satisfactorily approximated by a simple three-parameter formula.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
A method for calculating the radiative energy transfer in the Schuster–Schwarzschild approximation, which is used for the numerical simulation of the implosion of a composite shell-like Z-pinch under ...the action of the magnetic field of a high-current generator, is discussed. A significant part of the kinetic energy of the accelerated plasma shell, upon impact with the central insert, is converted into the energy of soft thermal X-ray radiation. The scheme for calculating radiant heat transfer in a medium with opacity that varies greatly in space and time is the key element of the technique required to optimize the conditions of the experiment on the conversion of the kinetic energy of the plasma shell into thermal radiation. The numerical technique proposed for multiparameter computational experiments makes it possible to obtain the dependence of the radiation energy density in the form of a quadrature on the opacity coefficient and plasma emissivity. In the two-temperature model of magnetic plasma implosion, this determines the contribution of radiant heat transfer to the energy balance of the electronic component.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Abstract
The results of experiments on the study of plasma compression of nested wire arrays of mixed composition and the generation of powerful pulses of soft x-ray radiation (SXR), carried out on a ...pulse power facility Angara-5-1 at a current level of up to 3 MA, are presented. Based on the latest experimental data on the intensity of plasma formation of various substances
m
˙
(in
μ
g(cm
2
ns)
−1
) (Mitrofanov
et al
2020
Plasma Phys. Rep.
46
1150–80) and on the features of the dynamics of plasma compression in nested arrays (Mitrofanov
et al
2018
Plasma Phys. Rep.
44
203–35), a nested wire array design has been developed which makes it possible to obtain a high peak SXR power in comparison with the known designs of single and nested tungsten wire arrays. During the implosion of nested arrays of mixed composition, consisting of plastic fibers and tungsten wires, shorter and more powerful SXR pulses were obtained with a maximum peak power
P
SXR
max
∼ 10 TW with a full width at half maximum (FWHM) duration of ∼5 ns compared to the parameters of SXR pulses upon compression of single tungsten arrays:
P
SXR
max
∼ 5 TW and FWHM ∼ 10 ns. Thus, under the conditions of our experiments, we have shown the possibility of a twofold increase in the peak SXR power during compression of nested arrays by optimizing their design.
We develop an algorithm for the numerical treatment of nonlinear heat conduction problems, which is adapted to the architecture of high-performance computing systems. The technique is based on a ...hyperbolic heat conduction model and explicit difference scheme. The new scheme provides the second-order temporal resolution of nonlinearity with an acceptable time step. Its application to plasma dynamic simulations is discussed.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
An approach for accelerating ions, with the use of a cluster-gas target and an ultrashort pulse laser of 150-mJ energy and 40-fs duration, is presented. Ions with energy 10-20 MeV per nucleon having ...a small divergence (full angle) of 3.4 degrees are generated in the forward direction, corresponding to approximately tenfold increase in the ion energies compared to previous experiments using solid targets. It is inferred from a particle-in-cell simulation that the high energy ions are generated at the rear side of the target due to the formation of a strong dipole vortex structure in subcritical density plasmas.
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A method for the numerical solution of a nonlinear equation describing the diffusion transfer of radiation energy has been developed. According to the method, the second time derivative with a small ...parameter is introduced into the parabolic equation and an explicit difference scheme is applied. The explicit approximation of the initial equation makes it possible to implement on its basis an algorithm that is effectively adapted to the architecture of high-performance computing systems. In comparison with the original scheme, the new one allows for a larger time integration step and a sufficiently high resolution of the solution structure, providing the second order of accuracy. A heuristic algorithm for choosing the parameters of the three-level difference scheme is proposed. A promising field of application of the method can be problems in plasma physics and astrophysics.
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