Determination of the electric field in a two-dimensional model of an electrothermal plasma source

Summary form only given. Electrothermal (ET) plasma discharges are arc-driven, capillary discharges that draw currents up to several tens of kA. These discharges have radii on the order of millimeters and lengths on the order of centimeters. They have a breadth of applicability ranging from materials processing to pellet injection for deep fusion fueling. A new simulation model and code have been developed to study these discharges in greater detail than has previously been possible. This model is two-dimensional and tracks the evolution of the electron, ion, and neutral species in the plasma discharge. A time-varying electrical current is used as a simulation input. The electric field inside the source is determined from the time-varying current and the distribution of the electrical conductivity in the source. The input electric current is considered to be only a function of time. Since the distribution of the electrical conductivity in the source is allowed to be non-uniform, the electric field is a function of position and must be determined to simulate the flow of charged particles in the plasma. Two separate approaches have been used in order to determine the electric field in the source. The first assumes that the electric field has only an axial component. Using this approach, the electric field is constant over the geometric cross section of the source and is computed at each axial location using Ohm´s law. The second approach allows for radial components of the electric field and variation of the electric field over the geometric cross section. This requires an iterative, two dimensional solution of a form of Poisson´s equation. The results of using these different approaches in the simulation of an ET plasma discharge are presented, and the differences are assessed and compared with previous models.