A Feedback Controller for the RFKO Method for Slow Extraction

The NIMMS (Next Ion Medical Machine Study) Group is designing an accelerator for medical applications that needs to extract a uniform spill of particles to the tumor. This is performed by slow extraction via the RF-KO (radio-frequency knock-out) method. The target of this project was to create a feedback system that can control this beam extraction. It is one of the first approaches to create a feedback system in simulation in the simulation code XSuite and it is also a promising method both for Slow Extraction at the NIMMS Group and for other users of the Xsuite community. A class in Xsuite was created, which tracks a beam through the Helium Synchrotron, which is simplified to a .json sequence line. A Beam Interact function was used to calculate the number of particles extracted per window (defined by the electrostatic septum), and fed this into the controller's class. The controller's class gets the beam data from Helium Synchrotron and passes them to the controller that calculates the necessary voltage kick and then applies this kick to the current beam. The tool's primary purpose is to facilitate control over the extraction process at the Helium Synchrotron, accommodating various factors such as the number of particles, emittance, sextupole strength, and tune distance. Previously, each RF-KO necessitated manual optimization based on an eight-variable function.