Improving Ion Source Antenna Lifetime for the Spallation Neutron Source

Robust H ion sources are a key component for the Spallation Neutron Source at ORNL. Antennas used to produce H ions often fail when plasma heats the protective insulating coating on the antennas, exposing the bare metal and causing structural failure. Reducing antenna failures, which are expensive and reduce the operating capability of the source, is the top priority of the SNS H Source Program at ORNL. Our numerical modeling of the plasma interaction with insulating surfaces in the H source will provide an optimization of antenna design that will reduce antenna failure for the SNS. We propose to use the high-performance computing software package USim to perform innovative simulations of plasma interactions with rf antennas in ion sources such as the one in use at SNS. We plan to develop specialized software modules that will allow researchers to easily model rf ion sources and other ion sources and take advantage of high-performance computing to optimize plasma device designs. In Phase I we determined that our fluids models will be able to simulate plasma-induced damage to the SNS H ion source antenna. We also demonstrated the ability to integrate spectral analysis and optimization techniques into our software technology in order to improve simulation capabilities. Successful completion of the Phase I tasks shows that our Phase II workplan is feasible and has a high probability of success. In Phase II we will provide complete simulation capability of the SNS H ion source plasma and antenna damage using different fluid-based models. We will integrate spectral analysis into our simulation code in order to simulate possible precursors to antenna coating melting. Finally, we will develop easy-to-use, modularized software specific to modeling ion sources. Commercial Applications and Other Benefits: As detailed in the commercialization plan, the ability to optimize plasma device design using computer models will help researchers and industrial companies in a number of fields, including ion source fabrication, ion implantation for the semiconductor industry, plasma processing, and thin film deposition. Researchers doing neutron scattering science at the SNS will also benefit from increased reliability as a result of reducing ion source downtime due to antenna failures at the facility.