HELICON PLASMA GENERATOR-ASSISTED H- ION SOURCE DEVELOPMENT AT LOS ALAMOS NEUTRON SCIENCE CENTER*

The aim of the helicon plasma generator-assisted negative ion source development at Los Alamos Neutron Science Center (LANSCE) is to use high-density helicon plasmas for producing intense beams of H- ions. Our work consists of two development paths, construction of a hybrid ion source (long-term goal) and replacement of the LANSCE surface converter ion source filaments by a helicon plasma generator (short-term goal). The hybrid ion source is a combination of a long-life plasma cathode, sustained by a helicon plasma generator, with a stationary, pulsed main discharge (multi-cusp H- production chamber) directly coupled to each other. The electrons are transferred from the helicon plasma to the cusp-chamber by thermal flow process to ignite and sustain the main discharge. Replacing the filaments of the ion source based on surface conversion process by a helicon plasma generator is a low-cost solution, building upon the well-proven converter-type ion sources. Both development paths are aimed at meeting the beam production goals of the LANSCE 800 MeV linear accelerator refurbishment project. This article provides a brief comparison of these approaches and describes the design and the status of the helicon-driven surface conversion H- ion source