## 6 Numerical Calculation Results
In the first half-period of the discharge current (when the main part of the energy is supplied to the discharge plasma, and the plasma parameters reach their extreme values), a time interval can be distinguished (starting from a certain moment of time \(t_{in}\) and practicallyuntil the end of the first half-period \(t_{1}\)) during which the spatial distributions of the main RPD parameters of the plasma acquire the property of quasi-stationarity, i.e., remain qualitatively similar in time. At the initial stage, a nonstationary transition occurs from the initial one (which simulates the \"breakdown\" phase of the interelectrode gap) to a quasi-stationary state. From the moment \(t=0\), the power capacitor starts to discharge through the gas plasma layer adjacent to the surface of the electrode system, providing the release of Joule energy in it and its heating. After reaching temperatures of 25 kK, the gas plasma begins to emit light streams with a density of 0.1-1 MW/ cm\({}^{2}\), causing the IDI material to heat up and vaporize. Here, we note that the initial phase of a quasi-stationary plasma formation is characterized by the absence of plasma of the erosion products of the central electrode. This is due to the time delay in the evaporation of the central electrode. The duration of the delay time can vary in the range 0.1-0.4 \(t_{m}\) and depends on the thermal physical properties of the electrode material, the density of the environment, and the power-power mode of the MPC-discharge. It can be seen in Figures 2 and 3 that the light erosion vapor entering the discharge zone is ionized and heated as a result of the combined action of radiation fluxes, plasma dynamic, and Joule heating. Under the action of gas dynamic and pondermotor forces, collapse on the MPC axis occurs, the light-erosion plasma of the dielectric is accelerated, and the gas is forced out of the regions adjacent to the surface of the electrode system. Figure 2: Lines of the density \(\rho\) (kg/m\({}^{3}\)) (**a**), temperature \(T\) (kK) (**b**) at the time \(t=15.3\) us at a discharge current \(J=281\) kA for an MPC with parameters \(C=750\) u\(E\), \(U_{0}=5\) kV in argon with pressure \(p=10^{-2}\) MPa (\(A_{m}=0.6\)). The electrode assembly: 1: contact boundary (CB), 2: shock-compressed gas (SCG), 3: shock-compressed plasma (SCP), 4: a shock wave in a gas (GSW), 5: a shock wave in plasma (PSW), 6: contact boundary separating the regions of the surrounding gas SCG and light erosion plasma SCP. \[p=10^{-2}\ \text{MPa}\ (A_{m}=0.6).\]  
The discharge current begins to flow mainly through the higher-temperature regions filled with light-erosion plasma, providing its further heating, acceleration, and the formation of characteristic quasi-stationary RPD structures. The initial stage ends at the moment of the formation of the characteristic structure of the outer region of the discharge plasma (Figure 1): a shock wave propagates through the undisturbed gas in the gas (GSW, pos. 1), a shock wave appears in the plasma of light-erosion vapors (PSW, pos. 11) and a contact boundary (pos. 3) separating the regions of shock-compressed gas (pos. 2) and plasma of light-erosion vapors (pos. 12). The duration of the initial stage \(t_{in}\) does not exceed 2 \(\upmu\)s (depending on the rate of energy input into the plasma load). At large values of the amplitude of the discharge current \(J_{m}\) and (or) with a decrease in the density of the surrounding gas \(\rho_{0}\), the operating mode of the MPC discharge changes from Ohmic to transient. This regime is characterized by an increase in plasma dynamic effects associated with an increase in the role of ponderomotive forces. In this case, in the first half-period of the discharge current, the structure and parameters of the MPC-discharge plasma have a number of characteristic distinctive features. The main elements of the structure of the plasma formation typical for this mode are shown in Figure 2a.