Moment Method Formulation for Beam Excitation of Waveguide Slots
- Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States)
This paper describes a moment method formulation for calculating the pickup and kicker impedances of a stochastic cooling waveguide structure. Slots carved in a waveguide wall will slow down the phase velocity of a wave in the waveguide. The reduction in phase velocity is a function of the slot length, width, and the spacing between slots. The coupling of the slots to the beam is proportional to the slot length. When the reduced phase velocity of the waveguide matches the beam velocity, the coupling of the slots will add constructively. In this slow-wave mode, the gain of the array is proportional to the number of slots and the bandwidth of the array is inversely proportional to the number of slots. Finite element methods for are poorly suited for solving electromagnetic problems with thin wall apertures. The thin wall causes the electromagnetic field pattern to vary rapidly in the vicinity of the aperture. For finite elements, this would require a fine mesh around the apertures resulting in very large matrices to invert. Also, finite elements yield the solution for the electromagnetic field everywhere in the problem. To calculate pickup and kicker impedances, the electromagnetic field has to be known only at the slots or along the beam path. For these reasons, a moment method approach will be used for calculating the pickup and kicker impedances.
- Research Organization:
- Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), High Energy Physics (HEP)
- DOE Contract Number:
- AC02-07CH11359
- OSTI ID:
- 1974004
- Report Number(s):
- FERMILAB-PBAR-NOTE-575; oai:inspirehep.net:862783; TRN: US2403428
- Country of Publication:
- United States
- Language:
- English
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