RF Heating Modeling Tools for Electron Cyclotron Resonance Ion Sources

The production of high-quality, high-charge-state ion beams is an area of intensive research and development worldwide for particle accelerators, atomic physics experiments, and industrial applications. In nuclear physics research, using rare isotope ion beams with extreme proton-to- neutron ratios provides insight into the synthesis of new elements and the discovery of rare nuclei. Electron cyclotron resonance ion sources (ECRIS) are used to supply high-charge state ions for all of these applications, by generating multiply charged ions through electron impact ionization in confined plasma. The key to producing high charge state ions in an ECRIS is efficient heating of the plasma electrons with electromagnetic waves. ECRIS operators have developed a number of techniques for boosting output. However, there exists only a rudimentary understanding of how these waves are absorbed by the plasma and energize the electrons. FAR-TECH, Inc. proposes to develop a suite of three sophisticated modeling tools to simulate rf heating of ECRIS plasmas by electromagnetic waves. The tools will address each aspect of the problem: wave propagation, absorption of wave energy by the electrons, and the production of ions in the confined plasma. The suite of tools will aid ECRIS users in improving the operation of existing ion sources and designing and building new ones. In order to develop comprehensive rf heating modeling tools for ECRIS plasmas, FAR- TECH proposes to perform the following during Phase I. First, a 3D COMSOL model for cavity modes with plasma will be developed. Then, characterize electron resonance with RF waves in a simple parabolic magnetic well, with a single rf wave, two waves, and with frequency tuning Finally, Monte-Carlo calculations will be made in a simple magnetic well to obtain a proper diffusion coefficient for Fokker-Plank bounce averaged electron equation that is used in FAR- TECHs Generalized ECRIS Modeling code (GEM), from which one can evaluate confinement time and extracted charge states. Commercial Applications and Other Benefits: Improving the efficiency of electron cyclotron resonance ion sources will improve the performance of radioactive ion beam facilities as well as industrial applications of highly charged ions.