Cyclotron Phase-Lock Loop Control

Technology

To promote optimal beam acceleration, these phase-lock loop synchronization techniques use feedback in the RF field to increase cyclotron current. This phase-controlling technique requires an optimized system of a source to monitor the beam during the acceleration phase. Such control systems require beam sensors and mechanisms located at the dees gap to accordingly adjust RF phase. The RF source phase (φsource) that optimizes beam acceleration depends on a function of sensor, beam-gap, beam, RF, and optimal phases. Additionally, use of a pulsed ion source made from appropriate materials (i.e. made of stable compounds that do not breakdown, employ an ablator that does not leave deposits or require maintenance operation) promotes matching of ion source to the acceptance window of the RF in cyclotrons.  

Problem Addressed

Synchrocyclotrons require adjustments to the frequency of radio frequency (RF) fields during beam acceleration due to the relativistic effects that change the mass of accelerated particles. Conventional efforts to monitor and control frequency occur after the extraction phase. These efforts lack real-time monitoring and appropriate synchronization of adjustments during the acceleration phase. Addressing the frequency of RF fields in the acceleration phase serves to substantially improve beam quality and promote optimal acceleration. These cyclotron improvements synchronize RF and beam phases to optimize acceleration of particles for efficient beam extraction. Such improvements for high current cyclotron design offer significant advantages for relevant applications, especially when coupled with other improvements such as use of magnetic field coils, magnetic shielding, and superconducting materials.  

Advantages

• Closed loop control enables variation of final beam energy
• Maintains high extraction efficiency