First digital self-excited loop (SEL)

The first digital self-excited loop (SEL) for radiofrequency (rf) controls has been developed as part of the 12 GeV R&D. The SEL is of interest to the 12 GeV Project, because it can energize a cavity even if it is not on resonance. Use of an SEL would thus eliminate the cavity turn-on challenge created by the large Lorentz-force detuning seen with cavities operating at the gradients planned for 12 GeV. The demonstrator has been able to achieve phase control in closed loop over a limited detuning range during this portion of the R&D work. Further development is planned to demonstrate the final phase and amplitude control specifications for 12 GeV.

Source - JLab