# An Investigation into the Behavior of Cathode and Anode Spots in a Welding Discharge
## 4 Discussion
[PERSON] [59] proposed measuring the pressure distribution of the arc plasma over the surface of the receptor plate with a gating hole in it. His findings indicate the normal law of pressure distribution over the anode spot. In [53; 54], the authors proposed a model that simulates the hydrodynamic situation in a bath during plasma-arc remelting, along with a method to study the nature of the bath metal's movement by measuring the hydrodynamic pressure. The study revealed that electromagnetic forces are the primary forces driving the melt's movement. The speed of movement of the melt increases with an increase in the current passing through it. The movement is directed from the arc down along the axis of the bath, at the surface, from the periphery to the center of the bath. We performed an experiment on a model to study the flows in the bath during plasma-arc remelting. It has been proven that the main driving force in the bath during plasma arc remelting is electromagnetic force. The high-speed pressure of the plasma arc gas flow acting on the melt's surface does not cause significant volume movement. The arc's base directs the main melt flow deep into the bath along its axis. The movement of the melt at the surface is from the periphery to the center. In the middle part of the bath's radius, vortices form. With an increase in the arc current, the nature of the flows does not change; their intensity increases. The structure of the anode layer of the vacuum arc bulk charge has been studied, taking into account the dependence of the negative anode drop on the ratio of the directional velocity of electrons to their thermal velocity for different values of the flux density of atoms evaporated from the anode [39; 40; 55]. The Poisson equation was solved in the layer, taking into account the volume charge of electrons, fast cathode ions, and slow ions formed during the ionization of atoms evaporated from the anode. We solved a kinetic equation for atoms and slow anode ions, considering the collision integral that accounts for ionization. We analytically obtained solutions for both the distribution function of atoms and slow ions by velocities, as well as for the concentration of the latter. The description of the nonequilibrium plasma in front of the metal surface emitting the electrodes is of great importance for theoretical studies of the thermal plasma of arcs because the correct boundary conditions on the electrodes are crucial for modeling arc discharge in general [48; 49; 50]. Experimental work shows that the arc voltage varies depending on the chemical composition of the anode [1; 2; 3; 40; 54; 60]. In [61], a mathematical model of the interaction of electric arc plasma fluxes and molten metal fluxes in the processed product was proposed, which allows us to consider interrelated processes in an electric arc on the surface and inside the product as a single picture. The developed model made it possible to obtain more complete information about the dynamics and interaction of processes in an electric arc and a welding bath and allowed us to determine such important characteristics as the melting depth of the base metal, the intensity of mixing of the metal, the transportation of impurities into the melt, etc. This model's unique solution describes the processes in each region using the same set of magnetic hydrodynamics (MHD) equations. It was found that the formation of liquid metal flows occurs under the influence of the viscous interaction of radially spreading plasma flows with the anode surface; under the influence of surface tension forces, the welding bath forms a \"mushroom\" shape. The shape of the surface of the welding bath and the depth of penetration of the base metal are determined by the balance of pressures from the arc and the welding bath. With increasing pressure in the energy balance of the arc column, heat losses increase due to increased radiation.