ICAP 2002 Abstracts and Posters

Status of the MICHELLE Electron Gun and Collector Modeling Tool

Abstract

The status of the development of a new three-dimensional electron gun and collector design tool is reported. This new simulation code has been designed to address the shortcomings of current beam optics simulation and modeling tools used for vacuum electron devices, ion sources, and charged-particle transport. The design tool specifically targets problem classes including gridded-guns, sheet-beam guns, multi-beam devices, and anisotropic collectors, with a focus on improved physics models. The code includes both structured and unstructured grid systems for meshing flexibility, along with a new method for accurate particle tracking through the mesh. In the area of particle emission, new models for thermionic beam representation are included that support primary emission and secondary emission. Also discussed are new methods for temperature-limited and space-charge-limited (Child's law) emission, including the Longo-Vaughn formulation. A new secondary emission model is presented that captures true secondaries and the full range of rediffused electrons.

The basic physics model in the code is based on the equilibrium steady state application of the electrostatic PIC approximation employing both structured and unstructured meshes. The fields are represented using the finite element method on conformal meshes, with suitable particle tracking algorithms.

The code employs a multiblock architecture, allowing flexibility in gridding and memory use, as well as hardware architecture adaptability. The current version of MICHELLE supports a multiblock, conformal structured hexahedral mesh in 3D, and unstructured meshes in 2D (triangles, quadrilaterals) and 3D (tetrahedrals, prisms, hexahedrals, pyramids). A description of the MICHELLE code is presented along with examples of Adaptive Mesh Refinement (AMR).and several examples illustrating the capabilities of the code.

J. Petillo, D. Panagos, P. Blanchard, A. Mondelli, K. Eppley, T. McClure - SAIC, E. Nelson - LANL, J. DeFord, B. Held, L. Chernyakova - STAR, N. Dionne - Raytheon, J. Burdette, X. Zhai - Boeing, M. Cattelino - CPI, R. True - Northrop Grumman, K. Nguyen - KN Research, B. Levush - NRL

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