Author: Matsumoto, S.
Paper Title Page
TUPME010 High-intensity and Low-emittance Upgrade of 7-GeV Injector Linac towards SuperKEKB 1583
 
  • K. Furukawa, M. Akemoto, D.A. Arakawa, Y. Arakida, A. Enomoto, S. Fukuda, H. Honma, R. Ichimiya, N. Iida, M. Ikeda, E. Kadokura, K. Kakihara, T. Kamitani, H. Katagiri, M. Kurashina, S. Matsumoto, T. Matsumoto, H. Matsushita, S. Michizono, K. Mikawa, T. Miura, F. Miyahara, T. Mori, H. Nakajima, K. Nakao, T. Natsui, Y. Ogawa, S. Ohsawa, F. Qiu, M. Satoh, T. Shidara, A. Shirakawa, H. Sugimoto, T. Suwada, T. Takatomi, T. Takenaka, M. Tanaka, Y. Yano, K. Yokoyama, M. Yoshida, L. Zang, X. Zhou
    KEK, Ibaraki, Japan
  • D. Satoh
    TIT, Tokyo, Japan
  
  After a decade of suc­cess­ful op­er­a­tion at KEKB a new elec­tron/positron col­lider, Su­perKEKB, is being con­structed to com­mis­sion within FY2014. It aims at a lu­mi­nos­ity of 8 x 1035 /s.​cm2, 40-times higher than that of KEKB, in order to study the fla­vor physics of el­e­men­tary par­ti­cles fur­ther, by mainly squeez­ing the beams at the col­li­sion point. The in­jec­tor linac should pro­vide high-in­ten­sity and low-emit­tance beams of 7-GeV elec­tron and 4-GeV positron by newly in­stalling a RF-gun, a flux con­cen­tra­tor, and a damp­ing ring with care­ful emit­tance and en­ergy man­age­ment. It also have to per­form si­mul­ta­ne­ous top-up in­jec­tions into four stor­age rings by pulse-to-pulse beam mod­u­la­tions not to in­ter­fare be­tween three fa­cil­i­ties of Su­perKEKB, Pho­ton Fac­tory and PF-AR. This paper de­scribes the in­jec­tor de­sign de­ci­sions and pre­sent sta­tus of the con­struc­tion.  
 
WEPFI018 Comparison of High Gradient Performance in Varying Cavity Geometries 2741
 
  • T. Higo, T. Abe, Y. Arakida, Y. Higashi, S. Matsumoto, T. Shidara, T. Takatomi, M. Yamanaka
    KEK, Ibaraki, Japan
  • A. Grudiev, G. Riddone, W. Wuensch
    CERN, Geneva, Switzerland
  
  Four types of CLIC pro­to­type TW ac­cel­er­a­tor struc­tures were high-gra­di­ent tested at Nex­tef, KEK, up to 100 MV/m level and the fifth is under test now. The ramp­ing speed of each pro­cess­ing and the re­sul­tant break­down rate were com­pared among them. From this com­par­i­son, it was found that the ramp­ing speed of the struc­tures with open­ing ports for HOM damp­ing with mag­netic cou­pling be­came slow and the re­sul­tant break­down rate be­came high. It was also found that that with lower sur­face mag­netic field showed faster ramp­ing in pro­cess­ing and lower break­down rate. This in­di­cates the role of the mag­netic field on vac­uum break­downs in cop­per struc­ture at the re­gion of sev­eral tens to 100 MV/m. In this paper, we re­view the pro­cess­ing stage and the high gra­di­ent per­for­mance of these struc­tures try­ing to dis­cuss the rel­e­vant pa­ra­me­ters, sur­face elec­tric field, sur­face mag­netic field and other pa­ra­me­ters such as Sc, “com­plex point­ing vec­tor”, to the per­for­mance dif­fer­ence.  
 
WEPFI019 High Power Test of Kanthal-coated L-band Lossy Cavity 2744
 
  • F. Miyahara, Y. Arakida, Y. Higashi, T. Higo, K. Kakihara, S. Matsumoto
    KEK, Ibaraki, Japan
  • K. Saito
    Hitachi, Ltd., Energy and Environmental System Laboratory, Hitachi-shi, Japan
  • H. Sakurabata
    Hitachi, Ltd., Power & Industrial Systems R&D Laboratory, Ibaraki-ken, Japan
  
  We have been de­vel­op­ing a Kan­thal (Al-Cr-Fe)-coated collinear load as a pos­si­ble can­di­date of the L-band acc. struc­ture of Su­perKEKB positron cap­ture sys­tem. In order to achieve the higher cap­ture ef­fi­ciency com­par­ing to that of KEKB, the up­grade of the e+ pro­duc­tion and cap­ture sec­tion is re­quired. The sys­tem con­sists of a W tar­get with a flux con­cen­tra­tor fol­lowed by acc. struc­tures sur­rounded by so­le­noids. The in­crease of the e+ bunch charge and the re­duc­tion of satel­lite bunches are the main is­sues for this sys­tem. The fre­quency choice of L-band is based on the larger trans­verse and lon­gi­tu­di­nal ac­cep­tances than those of the S-band one. The load is prefer­able to com­pose the sys­tem with com­pact mag­nets and to min­i­mize the dip in the so­le­noid field. The de­sign of the load was re­ported in pre­vi­ous work*. We un­der­stand that the Kan­thal-coated cell should be con­firmed in high power to con­firm the fea­si­bil­ity at our de­sign field of 10 MV/m level. We are mak­ing a test cav­ity which con­sists of 3 cells and one of them is com­posed of Kan­thal-coated disks to lower the in­trin­sic Q value from 20000 to the order of 1000. The cav­ity pro­duc­tion and the ex­per­i­men­tal re­sult will be re­ported.
*Development of L-band accelerating structure with Kanthal-coated collinear load for SuperKEKB, IPAC12, THLR04.