Refined Calculation of Beam Dynamics During UMER Injection

The University of Maryland Electron Ring (UMER) is built as a low-cost testbed for intense beam physics for benefit of larger ion accelerators [1]. The beam intensity is designed to be variable, spanning the entire range from low current operation to highly space-charge-dominated transport. The ring has recently been closed and multi-turn commissioning has begun. Although we have conducted many experiments at high space charge during UMER construction, lower-current beams have become quite useful in this commissioning stage for assisting us with beam steering, measurement of phase advance, etc. One of the biggest challenges of multi-turn operation of UMER is correctly operating the Y-shaped injection section, hence called the Y-section, which is specially designed for UMER multi-turn operation. It is a challenge because the system requires several quadrupoles and dipoles in a very stringent space, resulting in mechanical, electrical, and beam control complexities. This paper presents a simulation study of the beam centroid motion in the injection region.