Author: Ge, L.
Paper Title Page
TUPEA087 Experiment on Multipactor Suppression in Dielectric-loaded Accelerating Structures with a Solenoid Field 1319
 
  • C.-J. Jing, S.P. Antipov, A. Kanareykin, P. Schoessow
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • C. Chang, L. Ge, L. Xiao
    SLAC, Menlo Park, California, USA
  • M.E. Conde, W. Gai, R. Konecny, J.G. Power
    ANL, Argonne, USA
  • S.H. Gold
    NRL, Washington, DC, USA
  
  Funding: US DoE SBIR Phase I project under contract #DE-SC0007629
Ef­forts by nu­mer­ous in­sti­tu­tions have been on­go­ing over the past decade to de­velop a Di­elec­tric-Loaded Ac­cel­er­at­ing (DLA) struc­ture ca­pa­ble of sup­port­ing high gra­di­ent ac­cel­er­a­tion when dri­ven by an ex­ter­nal rf source. Mul­ti­pactor is the major issue lim­it­ing the gra­di­ent that was re­vealed in ear­lier ex­per­i­ments. A the­o­ret­i­cal model pre­dicts that the strength of so­le­noid field within an op­ti­mal range ap­plied to DLA struc­tures may com­pletely block the mul­ti­pactor. To demon­strate this ap­proach, two DLA test struc­tures have been built and the first high power test will be con­ducted in De­cem­ber 2012. The re­sults will be re­ported. 		 
 
WEPWO072 HOM Damping Coupler Design for the 400-MHz RF Dipole Compact Crab Cavity for the LHC HiLumi Upgrade 2468
 
  • Z. Li, L. Ge
    SLAC, Menlo Park, California, USA
  • S.U. De Silva, J.R. Delayen
    ODU, Norfolk, Virginia, USA
  
  Funding: Work partially supported by the US DOE through the US LHC Accelerator Research Program (LARP), and by US DOE under contract number DE-AC02-76SF00515.
Crab cav­i­ties are adapted as the base­line de­sign for the LHC Hi­Lumi up­grade to achieve head-on beam-beam col­li­sions for fur­ther im­prove­ment in lu­mi­nos­ity. A 400-MHz com­pact RF di­pole crab cav­ity de­sign was de­vel­oped by a joint ef­fort be­tween Old Do­min­ion Uni­ver­sity and SLAC under the sup­port of US LARP pro­gram. This de­sign has shown very fa­vor­able RF pa­ra­me­ters and can fit into the avail­able beam­line spac­ing for ei­ther ver­ti­cal and hor­i­zon­tal crab­bing schemes. A nio­bium pro­to­type cav­ity based on such a de­sign has been man­u­fac­tured for ver­ti­cal test. In ad­di­tion, there are strin­gent wake­field re­quire­ments that needed to be met for such a cav­ity in order to pre­serve the qual­ity of the cir­cu­lat­ing beams. In this paper, we will dis­cuss dif­fer­ent damp­ing schemes for such a com­pact de­sign and pre­sent the HOM cou­pler de­signs to meet the damp­ing re­quire­ments. 		 
 
WEPFI073 A Modular Cavity for Muon Ionization Cooling R&D 2860
 
  • D.L. Bowring, A.J. DeMello, A.R. Lambert, D. Li, S.P. Virostek, M.S. Zisman
    LBNL, Berkeley, California, USA
  • C. Adolphsen, L. Ge, A.A. Haase, K.H. Lee, Z. Li, D.W. Martin
    SLAC, Menlo Park, California, USA
  • D.M. Kaplan
    Illinois Institute of Technology, Chicago, Illinois, USA
  • T.H. Luo, D.J. Summers
    UMiss, University, Mississippi, USA
  • A. Moretti, M.A. Palmer, R.J. Pasquinelli, Y. Torun
    Fermilab, Batavia, USA
  • R.B. Palmer
    BNL, Upton, Long Island, New York, USA
  
  The Muon Ac­cel­er­a­tor Pro­gram (MAP) col­lab­o­ra­tion is de­vel­op­ing an ion­iza­tion cool­ing chan­nel for muon beams. Ion­iza­tion cool­ing chan­nel de­signs call for the op­er­a­tion of high-gra­di­ent, nor­mal-con­duct­ing RF cav­i­ties in multi-Tesla so­le­noidal mag­netic fields. How­ever, strong mag­netic fields have been shown to limit the max­i­mum achiev­able gra­di­ent in RF cav­i­ties. This gra­di­ent limit is char­ac­ter­ized by RF break­down and dam­age to the cav­ity sur­face. To study this issue, we have de­vel­oped an ex­per­i­men­tal pro­gram based on a mod­u­lar pill­box cav­ity op­er­at­ing at 805 MHz. The mod­u­lar cav­ity de­sign al­lows for the eval­u­a­tion of dif­fer­ent cav­ity ma­te­ri­als - such as beryl­lium - which may ame­lio­rate or cir­cum­vent RF break­down trig­gers. Mod­u­lar cav­ity com­po­nents may fur­ther­more be pre­pared with dif­fer­ent sur­face treat­ments, such as high-tem­per­a­ture bak­ing or chem­i­cal pol­ish­ing. This poster pre­sents the de­sign and ex­per­i­men­tal sta­tus of the mod­u­lar cav­ity, as well as fu­ture plans for the ex­per­i­men­tal pro­gram.  
 
WEPFI092 Multipacting Simulation of the MICE 201 MHz RF Cavity 2914
 
  • T.H. Luo, D.J. Summers
    UMiss, University, Mississippi, USA
  • D.L. Bowring, A.J. DeMello, D. Li, P. Pan, S.P. Virostek
    LBNL, Berkeley, California, USA
  • L. Ge
    SLAC, Menlo Park, California, USA
  
  The in­ter­na­tional Muon Ion­iza­tion Cool­ing Ex­per­i­ment (MICE) aims to demon­strate trans­verse cool­ing of muon beams by ion­iza­tion. The MICE ion­iza­tion cool­ing chan­nel re­quires eight 201-MHz nor­mal con­duct­ing RF cav­i­ties to com­pen­sate for the lon­gi­tu­di­nal beam en­ergy loss in the cool­ing chan­nel. Mul­ti­pact­ing is a res­o­nant elec­tron dis­charge pro­duced by the syn­chro­niza­tion of emit­ted elec­trons with the RF fields, which can cause break­down at high power RF op­er­a­tion. In this paper, we pre­sent the study of the mul­ti­pact­ing ef­fect in the MICE 201 MHz cav­i­ties with the SLAC ACE3P code. The sim­u­la­tion is car­ried out in the cav­ity body, the RF cou­pler re­gion, and the coax­ial wave­guide, with the ex­ter­nal mag­netic field from the Cou­pling Coil. We will iden­tify po­ten­tial RF break­downs due to mul­ti­pact­ing and pro­pose a so­lu­tion to sup­press them.