Computational Techniques to Assess the Effects of Ionization on High Power Electrical Systems

There are three general classes of codes that can be used in the analysis of electrical systems and their interactive effects: circuit codes, Maxwell´s-equations- solving codes (also referred to as field codes), and system codes. Circuit codes employ coupled equations to describe the currents and voltages associated with individual electronic components such as individual transistors, resistors, and capacitors. The largest group of codes is the Maxwel´s-equation-solving codes. Conceptually, these codes can be subdivided into frequency- or time-domain codes and statistical codes. There is an additional way of differentiating between the two major categories of Maxwell´s-equations-solving codes available for analyses in this area: those that cannot handle discrete particles or macro-particles, and those that can. These two major categories of codes are referred to as linear and nonlinear (self-consistent), since nonlinear effects such as volume or surface breakdown often require a self-consistent analysis. Finally, system codes are used to understand and study the relationship between various elements in a high-power system: sources, transmission lines, antennas, propagation effects, etc. System codes consider the constraints on an electrical system, such as size, weight, and power, and are used to define what components may be used to deliver the required results. The element that most frequently limits a given code´s capability to adequately model a system lies in understanding and depicting electron-interaction phenomena with other particles, gas breakdown and streamer formation, and the effects of photo ionization. This paper is based on a study carried out by the Air Force Research Laboratory in 2003 to review the available codes and determine their capability to assess the effects of ionization on advanced high power electrical systems [1].