Study of interaction between plasma flows and the magnetic field at the implosion of nested wire arrays

Abstract

At the Angara-5-1 facility investigation was carried out which studied the interaction of plasma flows and the magnetic field. They are created by the current implosion of cylindrical nested wire arrays, the inner and outer array of which are composed from thin wires or dielectric fibers. It has been shown experimentally that at the plasma formation stage it is possible to realize various modes of interaction between plasma flows and the magnetic field of the discharge current inside the nested array. A mechanism is proposed for the interaction of plasma flows of the outer array with the magnetic field and the current-carrying plasma of the inner array. The stability of the plasma compression of the inner array at the final stage of its compression depends on the nature of this interaction. Obtained experimental data on the dynamics of interaction of plasma flows with the magnetic field in the gap between arrays are compared with the results of 2D-simulation of the implosion of nested arrays according to the RMHD MARPLE code. It is experimentally and theoretically confirmed that when a nested array is imploded with certain parameters around the inner array, a plasma quasi-closed shell is formed in the azimuthal direction.

Progress in researching the implosion of nested arrays of mixed composition and the generation of soft x-ray power pulse

“…In the experiments carried out at the previous stage of studies of the implosion of nested arrays of mixed composition [44][45][46]56], it was found that the stability of the plasma compression of the inner array (in our case, the W assembly) at the final stage of implosion depends on the nature of the interaction of the plasma flows of the outer array with the magnetic field of the discharge current of the inner array. A decrease in the growth rate of plasma MRT instability of the W-array with an increase in the number of fibers in the outer array N out , which was observed in a wide range of ratios of the radii of the arrays r in /r out = 0.3-0.9, was recorded.…”

“…Good agreement was observed between the simulation results and experimental data. For example, it was shown in the works [44,56] that with an increase in the number of fibers N out in the outer array and the formation of an SW region in the space between the arrays near the outer surface of the inner array (W-array), conditions are created for suppressing the MRT instability inherent in plasma compression single wire arrays. A possible scenario for the interaction of the plasma of the outer and inner arrays (shockwave mechanism) is proposed.…”

“…For this, it is necessary to select the substance of the wires or plastic fibers in the arrays so that the intensity of the plasma production of the fibers of the outer array is less than the intensity of the plasma production of the W-wires of the inner array − ṁout < ṁin [52]. It has been shown experimentally and theoretically [44][45][46]56] that when the ratio of the radii of the arrays r in /r out ≈ 0.5-0.7 and the plasma production rates ṁin / ṁout ≈ 1.8-4, conditions are created under which the kinetic pressure of the plasma flow from the outer array at a certain radius r SW is balanced by the magnetic pressure of the discharge current of the inner array, i.e. 1 /2ρV r 2 ≈ (B in ) 2 /8π.…”

Plasma channel formation in the knife-like focus of laser beam

“…It was successfully used to model several experiments. These include experiments on laser wake field accelerators of electrons in capillary discharges (Bagdasarov et al 2017a,b,c;Gonsalves et al 2019), experiments with dense Z-pinches formed by multi-wire arrays in pulsed power facilities (Grabovski et al 2008;Aleksandrov et al 2014Aleksandrov et al , 2019Olkhovskaya et al 2015) and experiments on the solid matter response to high intensity electron beams (Ananyev et al 2017;Gasilov et al 2019), etc.…”