Steering optimizations for the university of maryland electron ring∗

The University of Maryland Electron Ring is a dedicated research accelerator facility. UMER has the flexibility to set up alternative lattices for different research experiments. Existing beam-based alignment tools can take a significant amount of time to run and become difficult to process with a low ratio of BPMs to integer tune. The Robust Conjugate Directional Search (RCDS) optimizer is used to quickly obtain acceptable steering solutions for different lattice configurations and has been one of the techniques adopted for beam steering at UMER [1]. The algorithm optimizes steering magnets online to reduce scraping, correct equilibrium orbits, and increase beam lifetimes. We present some early steering results using this technique. INTRODUCTION UMER is a low energy (10 keV), high current (0.6-80 mA) electron storage ring. The machine is used to conduct scaled experiments applicable to larger accelerators. Most recently, studies on nonlinear beam dynamics [2]. Precision beam control is critical to the success of many experiments on UMER. Optimizing beam quality requires us to minimize closed orbits, maximize beam lifetime, and optimize injection. Traditional large accelerator facilities typically rely on orbit response matrix (LOCO) techniques to correct the machine’s linear optics [3]. These techniques have been attempted at UMER, but did not offer satisfactory results due to limitations of the machine. Figure 1: Left: Standard section with 4 quads (blue), 2 dipoles (green), and 1 vertical corrector (red). Right: Extra corrector section with 2 extra vertical correctors put in. UMER has a low ratio of BPMs (14) to integer tune (6) making it difficult to apply steering corrections based off BPM measurements. The machine is also understeered due to a small number of corrector magnets. Each period of the lattice contains 4 quadrupoles, 2 horizontal correctors, 1 vertical corrector, and 1 BPM (Table 1). A few sectors have since been upgraded with more vertical correctors as seen in Figure 1. All magnets are printed circuit and have their own power supplies; this allows the dipoles to be used as ∗ Funding for this project provided by DOE-HEP † levondov@umd.edu horizontal correctors around the ring [4]. Imperfections in some printed circuit magnets cause higher order field terms to appear, further complicating steering in the machine. Table 1: UMER Storage Ring Magnets