Title :
HOM damping performance of JLab SL21 cryomodule
Author :
Wang, Huifang ; Campisi, I. ; Beard, K. ; Rimmer, Robert ; Thomas, C. ; Mammosser, J. ; Preble, J.
Author_Institution :
TJNAF, Newport News, VA, USA
Abstract :
The SL21 cryomodule is a first 1.5 GHz, 12.5 MV/m, 7-cell cavity, 8-cavity string superconducting accelerator module produced at JLab. The first two passbands of TE111 and TM110 high order modes (HOM) have to be damped to avoid beam breakup problems at 460 μA current. External Q´s of the HOM couplers and waveguide were measured on a copper model, on cold niobium cavities in vertical tests and finally in the cryomodule without beam. This paper presents all HOM data and general measurement techniques. A threshold current predicted by MATBBU code based on these data and the 6 GeV machine beam optics is 10 mA.
Keywords :
accelerator cavities; superconducting cavity resonators; 1.5 GHz; 10 mA; 460 muA; 6 GeV; 8-cavity string superconducting accelerator module; HOM couplers; HOM damping; HOM waveguide; JLab SL21 cryomodule; MATBBU code; TE111 high order mode; TM110 high order mode; beam breakup problems; cold niobium cavities; copper model; machine beam optics; Copper; Couplers; Damping; Measurement techniques; Niobium; Optical beams; Optical waveguides; Passband; Testing; Threshold current;
Conference_Titel :
Particle Accelerator Conference, 2003. PAC 2003. Proceedings of the
Print_ISBN :
0-7803-7738-9
DOI :
10.1109/PAC.2003.1289619
