Physical Review Accelerators and Beams
A compact, harmonically resonant cavity with fundamental resonant frequency 1497 MHz was used to evaluate the temporal characteristics of electron bunches produced by a 130 kV dc high voltage spin-polarized photoelectron source at the Continuous Electron Beam Accelerator Facility (CEBAF) photoinjector, delivered at 249.5 and 499 MHz repetition rates and ranging in width from 45 to 150 picoseconds (FWHM). A cavity antenna attached directly to a sampling oscilloscope detected the electron bunches as they passed through the cavity bore with a sensitivity of ∼1 mV/μA . The oscilloscope waveforms are a superposition of the harmonic modes excited by the beam, with each cavity mode representing a term of the Fourier series of the electron bunch train. Relatively straightforward post-processing of the waveforms provided a near-real time representation of the electron bunches revealing bunch-length and the relative phasing of interleaved beams. The noninvasive measurements from the harmonically resonant cavity were compared to measurements obtained using an invasive RF-deflector-cavity technique and to predictions from particle tracking simulations.
Original Publication Citation
Roberts, B., Hannon, F., Ali, M. M., Forman, E., Grames, J., Kazimi, R., . . . Speirs, D. (2016). Harmonically resonant cavity as a bunch-length monitor. Physical Review Accelerators and Beams, 19(5), 052801. doi:10.1103/PhysRevAccelBeams.19.052801
Roberts, B.; Hannon, F.; Ali, M. M.; Forman, E.; Grames, J.; and Kazimi, R., "Harmonically Resonant Cavity as a Bunch-Length Monitor" (2016). Physics Faculty Publications. 134.