Speakers
Description
The ESS-Bilbao injector is a multipurpose machine that will accelerate protons up to 3 MeV. It will be used to produce neutrons by means of a Beryllium target. The first part of the injector has been running smoothly for more than a decade. This is formed by a proton source of the Electron Cyclotron Resonance (ECR) type that posseses unique characteristics. The subsequent Low Energy Transport section (LEBT) makes use of two solenoid magnets to transport and optimize the beam parameters for the Radio Frequency Quadrupole (RFQ). To enhance LEBT transmission and address the continuous plasma impedance variations during operation, we employ numerical optimization techniques, specifically Bayesian optimization.
On the other hand, we have used genetic algorithms to tune the RFQ cavity. In the RFQ resonant cavity (which is a 3 meters long linear accelerator) there are deviations from the desgiend uniform voltage profile, caused by local frequency variations that are a consequence of the modulation, the assembly and other assimetries. This deviations are corrected by adjusting the penetration of 62 plunger tuners. The combined action of the tuners modifies the field profile in order to achieve an uniform voltage (field profile). The adequate combination of tuners penetration is usually selected by a combination of an experimental technique (bead-pull measurements of field profiles, and their change for all the tuner actions) together with an algebraic approach for inverting the transfer matrix of the tuning system. This is usually done by a SVD psudo-inerse or equivalent algorithm. We propose an alternative method that instead of using the SVD approach selects the optimum tuner configuration by employing a genetic algorithm. The results of the complete assembly yield promising results, and are compared to the actualt measurements of the ESS-Bilbao RFQ.
