The front end of the 800-MeV proton linac at the Los Alamos Neutron Science Center (LANSCE) is still based on Cockcroft-Walton voltage generators that bring proton and H- beams of various flavors to 750 keV. We have developed 3D CST models of the LANSCE front-end elements including low-frequency and main bunchers. The fields in these elements are calculated with MicroWave and ElectroMagnetic Studio. Beam dynamics is modeled with Particle Studio for beams with realistic charge distributions using the CST calculated fields. The modeling results provide insight into linac operations and a guidance for designing a modern, RFQ-based front end for the LANSCE linac.

We present the 100 MeV injector design for the LANSCE Accelerator Facility, which is designed to replace the existing 750-keV Cockcroft-Walton-columns-based injector. This new Front End includes two independent low-energy transports for H+ and H- beams merging at the entrance of a single RFQ, with the subsequent acceleration of particles in the new Drift Tube Linac. The challenge of this design is associated with the necessity of simultaneous acceleration of protons and H- ions with multiple beam flavors in a single RFQ and DTL. The LANSCE operation regime provides simultaneous delivery of beams to five experimental areas, with a forecasted increase in the number of targets in the future. Each beam is characterized by a unique time structure, pulse length, emittance, and charge per bunch. The paper presents the details of this design and injector parameters.