Characterization of the Nonlinear Focusing Magnet for Quasi - Integrable Optics Experiments at the University of Maryland Electron Ring

The University of Maryland Electron Ring (UMER) group is in the process of an experiment to test a new accelerator theory that mitigates beam loss from resonances, yet still supports stable beam orbits [1]. A nonlinear magnet element (an octupole channel consisting of several separate flexible printed circuit boards (PCBs)) has been constructed with preliminary measurements [2]. We present work done to characterize the channel. We use a Velmex stage with a Hall probe to generate gridded magnetic field measurements. This method gives a direct way to achieve fine resolution of the longitudinal dependence of the focusing field, which is a fundamental component of the nonlinear focusing theory. We concluded that the needed octupole strength profile is achievable and that given our assumptions of the measurement error, the magnetic center through the length of the channel remains within an acceptable tolerance.