High Fidelity Simulation of Low-Energy Ion Beam Chopping for the Spallation Neutron Source

The DOE Office of Basic Energy Sciences (BES) plans to construct and operate a two-solenoid, low-energy beam transport (LEBT) system for 60 mA H- beams. The system is to include RF chopping. The motivation is to increase the total beam power of the Spallation Neutron Source (SNS) to 2¿3 MW by increasing the beam current, as well as the final ion energy. However, in previous attempts to combine robust solenoid-based LEBT designs with beam chopping, significant problems arose, due to the drift of neutralizing background ions into the chopping region. In this project, a parallel simulation framework, VORPAL, will be used to simulate the H- ion beam transport experiments that are being planned as part of the long-term SNS power upgrade at Oak Ridge National Laboratory (ORNL). Phase I will use data from the planned experiments to validate the utility of the simulations, including complicated electrode geometries and impact ionization physics. By the end of Phase II, state-of-the-art software, capable of designing future low-emittance LEBT configurations, will be developed. Commercial Applications and other Benefits as described by the awardee The proposed work will significantly enhance the VORPAL software, which is already a successful commercial product. In addition to the DOE application, the added features and new expertise will be directly relevant to important commercial applications, such as compact deuterium on tritium neutron sources for homeland security and oil exploration, and ion implantation for the semiconductor industry.