Damping Test of the Higher-Order Modes of the Re-Entrant Accelerating Cavity
- 1 June 1981
- journal article
- Published by Institute of Electrical and Electronics Engineers (IEEE) in IEEE Transactions on Nuclear Science
- Vol. 28 (3) , 2915-2917
- https://doi.org/10.1109/tns.1981.4331958
Abstract
Higher-order modes were studied in a model cavity (500 MHz re-entrant single cell cavity) which was designed for the KEK-PF 2.5 GeV electron storage ring. The longitudinal electric field and the transverse electric and magnetic fields were measured near the beam axis for the higher-order modes. The observed parameters of the TMO-mode resonances were in reasonable agreement with the SUPERFISH calculation. The TM011-like resonance at 758 MHz has the highest shunt impedance of 3.0 MΩ. The observed transverse coupling impedances of the HEMl modes at 829 MHz (TM110-like) and 1071 MHz (TM111-like) were 12 NΩ/m and 27 MΩ/m, respectively. Damping couplers are being developed to prevent the cavities from driving the coupled-bunch instabilities. The impedances were reduced to less than 0.01 MΩ and 0.2 MΩ/m for almost all of the TM0- and HEMl-mode resonances, respectively, in a low power test.Keywords
This publication has 2 references indexed in Scilit:
- Current limitations due to RF parameters in the photon factory storage ringNuclear Instruments and Methods, 1980
- Field Strength Measurements in Resonant CavitiesJournal of Applied Physics, 1952