Standard test case runs for the empulse monopole fieldsolver and conductivity generation model

Abstract

Abstract : At the high current beam propagation workshop it was realized that fieldsolver comparisons between working groups should be made for beams with expanded heads such as develop by blowoff and erosion during propagation. To facilitate comparisons of the fieldsolvers while removing the differences due to evolution of the beam during propagation, standard test cases with imposed beam head profiles were suggested. Hence, unambiguous field and conductivity generation calculation comparisons can be made. The field equations solved for this report are derived elsewhere. The plasma generation model includes a direct deposition term, an avalanche ionization term based on experimental data, and a recombination term. Plasma density is related to a scalar conductivity through the momentum transfer collision frequency. The actual coded fieldsolver used for the results in this report was extracted from the EMPULSE II code. The PHOENIX code was constructed to run this fieldsolver and generate the appropriate diagnostic output. Standard test cases are proposed where the beam current density is prescribed at all points in space. This is accomplished using a simple parameterized profile which can represent a cylindrical beam or one with an eroded nose. Four test cases are proposed; PHOENIX results for these cases are presented.