## 2 MPC and Plasma Discharge  
Improving the physical and technical characteristics of compact radiation sources and pulsed plasma jets has been the object of research for scientists around the world over the past decade. The study of such a plasma is of interest for various areas of technical physics: physics of nonequilibrium high-density plasma; expanding recombination plasma physics; atomic and molecular spectroscopy; physics of scattering, large-scale, long-lived radiating plasma formations (taking into account the presence of an external magnetic field) interacting with the background environment; and physics of chemically and laser-active media [6; 7; 8; 9; 10]. One of the promising methods for thermalizing the kinetic energy of the plasma flow (created by a special, pulsed plasma accelerator of the erosion type--a magneto plasma compressor (MPC)) is the use of a gas that acts as a deformable barrier [11; 12; 13]. In this case, the main configuration of the electrode assembly is a coaxial electrode system (Figure 1) with a short channel length \(<1\) cm (end-type MPC discharge) with a central electrode diameter of 0.8-1.5 cm and an outer electrode of \(2r_{2}=3\div 10\) cm. Energy storage is low-inductive (less than 100 nH) capacitor banks with a capacity \(C\) of 30 to 900 \(\upmu\)F with stored energy \(W_{0}=0.3\)-500 kJ. In this case, variations in the duration of the current pulse of the discharge can be 5-100 \(\upmu\)s for the range of the current amplitude \(J_{m}\approx 100\div 2000\) kA. With the model MPC configuration chosen as the base, the diagram of the equivalent electric-discharge circuit with a capacitive energy storage and the qualitative structure of the formed plasma is shown in Figure 1. The end-type MPC electrode assembly is a system of coaxial electrodes separated by an interelectrode dielectric insert (IDI). The origin of the cylindrical coordinate system \(R0Z\) is located in the center of the central electrode, the 0Z axis is the axis of symmetry; the axis \(0r\) runs along the plane of the end face of the electric discharge system. The formation of an MPC-discharge plasma in a gas is three-dimensional in nature, determined by azimuthal fluctuations of the thermal gas dynamic parameters of the plasma and gas in the formed shock wave (SW)-structures and contact boundaries. These fluctuations are caused both by the spatiotemporal inhomogeneity of the plasma parameters at the initial (breakdown) stage and by the subsequent development of magneto gasdynamic instabilities [14]. The initial stage of the discharge development--the stage of breakdown of the interelectrode gap with a duration of \(\leq\)1 \(\upmu\)s--is characterized by a pronounced inhomogeneity of the distribution of plasma parameters in the interelectrode gap in azimuth. This stage ends with the formation of a narrow (\(\sim\)1 mm) layer of weakly ionized, vapor-gas plasma adjacent to the surface of the end face of the \(W\)-\(W_{0}\) electrode system, short-circuiting the interelectrode gap. The energy spent at the breakdown stage and the initial stage of the discharge, from the energetic point of view, does not have a significant effect on the further plasma dynamics of the MPC discharge. Figure 1: MPC diagram and general structure of a plasma discharge IPC diagram: 1—shock wave (SW) in gas; 2—shock-compressed gas; 3—contact boundary; 4—region of the accelerated plasma of interelectrode dielectric insert (IDI); 5—area of shock-compressed plasma of IDI vapors; 6—plasma of vapors of the central electrode; 7—border of the area of radiation exposure; 8, 10—central and outer electrodes; 9—IDI; 11—chamber walls (or the boundary of the computational domain D).