NON INVASIVE BEAM MONITORING WITH HARMONIC CAVITIES
Brock Franklin Roberts
B.S PHYSICS, UNIVERSITY OF CALIFORNIA DAVIS, 1992
DOCTOR OF PHILOSOPHY IN ELECTRICAL ENGINEERING
UNIVERSITY OF NEW MEXICO, 2019
A cavity designed to have multiple harmonic TM0N0 modes can be used to accurately measure the longitudinal profile of a bunched charged particle beam passing through its bore, non-invasively, and in real time.
Multi-harmonic TM0N0 cavities were designed, constructed, and beamline tested in a variety of experiments at the Thomas Jefferson National Accelerator Facility (TJNAF or Jlab). Measurements with a sampling oscilloscope provided signals that resemble the profile of electron bunches passing through the cavity’s bore. Straightforward signal processing techniques reduce distortion in the measurement and provide real time profiles of electron bunches with picosecond accuracy. Subharmonic beams having bunch repetition rates of 1/3rd and 1/6th of Jlab’s 1497 MHz bunch frequency, and interleaved sub-harmonic beams were also measured. Comparison between measurements made using a harmonic cavity were corroborated with an established invasive measurement method and with computer models. A harmonic cavity from this effort has been installed within the CEBAF injector, allowing accelerator operators to view, in real time, the shape and duration of electron bunches entering the accelerator. Another harmonic cavity has been installed within Jlab’s Upgraded Injector Test Facility (UITF), and two more are planned for installation there. This effort was awarded the 2016 International Beam Instrumentation Conference’s Faraday Cup Award.
Beam monitor, harmonic cavity, bunch shape monitor, multi harmonic cavity
Level of Degree
Electrical and Computer Engineering
First Committee Member (Chair)
Second Committee Member
Third Committee Member
Roberts, Brock F.. "Non-invasive beam monitoring with harmonic cavities." (2019). https://digitalrepository.unm.edu/ece_etds/459