Effect of the plasma self-radiation on the growth of thermal filamentation instabilities in imploding Z pinches

Abstract

The development of thermal filamentation (TF) instabilities in a current-carrying plasma shell under the action of the plasma self-radiation was analyzed in terms of a small perturbation theory. A stationary collisional radiative model was used to calculate the parameters of the bremsstrahlung, recombination radiation, and spectral line radiation. It has been shown that radiative losses can either enhance or weaken the growth of TF instabilities. The pattern of the effect is governed by the dependence of the energy lost by the plasma due to radiation, Q Rad, on the plasma temperature T. If Q Rad increases slower than ∼T, the radiative losses enhance TF instabilities. In the opposite case, that is when Q Rad increases faster than ∼T, the radiative losses lead to suppression of TF instabilities. When the energy lost due to radiation is greater than the Joule energy input, TF instabilities can be completely stabilized due to radiation. The plasma parameter ranges for which stabilization of TF instabilities may occur due to radiation have been found for aluminum and argon.

Filamentation of the surface plasma layer during the electrical explosion of conductors in strong magnetic fields

“…Using expressions ( 27) and (30), for the conditions of the experiments performed of the ZEBRA generator [15], we obtain that the growth time of thermal instabilities, , is 50-100 μm for a plasma temperature of 3-5 eV. For the conditions implemented with the MIG generator [22], both the growth time of thermal instabilities and their wavelength are about twice longer.…”

“…This is observed in experiments on the electrical explosion of conductors. If the resistivity of a material decreases with increasing temperature, as is the case for high-temperature plasmas, thermal instabilities give rise to the formation of current channels (filaments) [27][28][29][30].…”

“…Expression (30) indicates that the value of the wave vector is determined only by the electric field strength and the temperature of the material. Note that this is true not only for the filaments developing in a plasma, but also for the strata formed during the electrical explosion of a conductor [25,26].…”

“…If the resistivity of a material increases with temperature, as is the case, for example, of a liquid metal, the thermal instabilities lead to the formation of strata [19,25,26], that is, layers normal to the current flow direction. In the opposite case, when the resistivity decreases with increasing temperature, as is the case of a high-temperature plasma, the development of thermal instabilities should lead to the formation of individual current channels [27][28][29][30]. In this paper, the development of filament instabilities of the surface plasma layer formed during the explosion of metal conductors in strong magnetic fields is analyzed based on a theory of small perturbations.…”

Study of the electrothermal and MHD instabilities in exploding cylindrical foil liner

“…Campbell et al studied the stabilization effect of MHD instabilities via helical return-current structure of ultrathin (0.65 μm) liner Z-pinch implosion on the Michigan Accelerator for Inductive Z-pinch Experiments (MAIZE) [17,18]. Oreshkin et al studied the stratification and filaments of exploding foils and investigated the effect of radiation on perturbation development [19]. Atoyan et al studied the suppression of plasma instabilities by insulated coatings in an exploding liner on COBRA [20].…”