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Description
Ever since the first non-classical isochronous cyclotron was invented in 1956, the stability of the isochronism of this kind of accelerator has been pursued for decades. For the CYCIAE-230 superconducting cyclotron, the matching between the RF frequency and the magnet field is even more challenging. A dedicated 2nd harmonic resonator has been designed, manufactured, and installed on the beamline to track the phase drift of the cyclotron-extracted beam. Front-end electronics and embedded software have been implemented to detect and broadcast the beam phase via a local Ethernet connection. A dedicated software has been developed to trace the phase error and constantly regulate the frequency of the master oscillator of the cyclotron in a predefined frequency range. The same software also takes supervisory control of the excitation current of the superconducting coil and the temperature of the magnet. Online tests have been conducted using the cyclotron beam and the phase probe system. Preliminary results indicate that the resonator has a good signal-to-noise ratio and can detect magnetic field drift in the order of 10^-7. In the meantime, the system can also be used as a non-invasive beam current detector, providing valuable information to the beam current regulation system. This paper reviews the design of the phase probe, electronics, and software, along with preliminary test results.
