Author: Li, Z.
Paper Title Page
TUPWA013 Study of the C-ADS Longitudinal Beam Instabilities Caused by HOMS 1751
 
  • P. Cheng, Z. Li, J.Y. Tang, J.Q. Wang
    IHEP, Beijing, People's Republic of China
  
  The C-ADS ac­cel­er­a­tor is a CW pro­ton linac which ac­cel­er­ates the beam to 1.5GeV. It has the char­ac­ter­is­tics of being very high beam power and very high re­li­a­bil­ity that are not posed by any of the ex­ist­ing pro­ton linacs. The ac­cel­er­a­tor uses two fam­i­lies (β=0.63 and β=0.82 ) of el­lip­ti­cal five cell su­per­con­duct­ing cav­i­ties. High Order Modes can se­verely limit the op­er­a­tion of these cav­i­ties. Mono­pole modes are found by Mi­crowave Stu­dio CST. Then the lon­gi­tu­di­nal in­sta­bil­ity caused by these mono­pole modes are pri­mar­ily in­ves­ti­gated with code bbusim, tak­ing into ac­count of ef­fects like High Order Modes fre­quency spread, beam input jit­ters and other beam and RF pa­ra­me­ters of the beams and cav­i­ties. Pre­lim­i­nary sim­u­la­tion re­sults show that mono­pole modes in­duced in­sta­bil­ity is not a prob­lem if High Order Modes fre­quency spread is not less than 1MHz. How­ever, fur­ther in­ves­ti­ga­tions are nec­es­sary in order to make a crit­i­cal de­ci­sion such as whether HOM damper will be adopted. Study on the trans­verse case is under way.  
 
TUPWA018 Local Compensation-Rematch for Element Failures in the Low Energy Section of C-Ads Accelerator 1760
 
  • B. Sun, Z. Li, J.Y. Tang, F. Yan
    IHEP, Beijing, People's Republic of China
  
  Due to the re­quire­ment of high re­li­a­bil­ity and avail­abil­ity for the C-ADS ac­cel­er­a­tors, a fault tol­er­ance de­sign is pur­sued. The ef­fects of trans­verse fo­cus­ing el­e­ment fail­ures in dif­fer­ent lo­ca­tions have been stud­ied and the schemes of com­pen­sa­tion by means of local com­pen­sa­tion have been in­ves­ti­gated. After one trans­verse el­e­ment fail­ure es­pe­cially in the low en­ergy sec­tion hap­pens, some new meth­ods have been pur­posed by which the new set­tings of the neigh­bour­ing so­le­noids and the cav­i­ties can be set, and the Twiss pa­ra­me­ters and en­ergy can be ap­prox­i­mately re­cov­ered to that of the nom­i­nal ones at the match­ing point. We find that the nor­mal­ized RMS emit­tance in trans­verse and lon­gi­tu­di­nal planes have no ob­vi­ous growth after ap­ply­ing the com­pen­sa­tion in each sec­tion of the main linac. When we make study on the com­pen­sa­tion-re­match for the RF cav­ity fail­ures, the TraceWin code has been used that doesn’t con­sider the phase change dur­ing the cav­ity re­set­ting, so a code named LOC­COM, which is based on MAT­LAB, is de­vel­oped and used to com­pen­sate the error on ar­rival-time at the match­ing point.  
 
TUPWA020 The Implementation of Equipartitioning in the Proton Linac Code PADSC 1766
 
  • Y.L. Zhao, S. Fu, Z. Li
    IHEP, Beijing, People's Republic of China
  
  The high in­ten­sity ac­cel­er­a­tor pro­jects place ex­tremely strin­gent re­quire­ments on par­ti­cle loss, since even very small losses can lead to un­ac­cept­ably high lev­els of ra­dioac­tiv­ity that can hin­der or pre­vent hands-on main­te­nance. Such losses are known to be as­so­ci­ated with emit­tance growth and beam halo. Non-equipar­ti­tion­ing con­tributes a lot for emit­tance growth and beam halo. The pre­sent equipar­ti­tion­ing re­al­iza­tion has as­sumed that the emit­tance and space charge force are keep­ing con­stant, which will in­duce er­rors. The im­ple­men­ta­tion in the pro­ton linac code PADSC does equipar­ti­tion­ing op­ti­miza­tion ac­cord­ing to the real space charge force and emit­tance in the quasi pe­riod lat­tice.  
 
TUPWO019 A Local Achromatic Design of C-ADS MEBT2 1922
 
  • H. Geng, Z. Guo, Z. Li, C. Meng, S. Pei, J.Y. Tang
    IHEP, Beijing, People's Republic of China
  
  The ac­cel­er­a­tor of China Ac­cel­er­a­tor Dri­ven Sub-crit­i­cal sys­tem con­sists of two in­jec­tors to en­sure its high re­li­a­bil­ity. The Medium En­ergy Beam Trans­port line-2 is an es­sen­tial part of the ac­cel­er­a­tor to trans­port and match the beam from ei­ther in­jec­tor to the main linac. This paper pre­sents a local achro­matic de­sign, which uses four bend­ing mag­nets, for CADS MEBT2. It is found that both trans­verse and lon­gi­tu­di­nal emit­tance growths can be well con­trolled below 15% from MEBT2 en­trance to the exit of the fol­low­ing su­per­con­duct­ing spoke-021 sec­tion. The beam dy­nam­ics of MEBT2 will be dis­cussed and the multi-par­ti­cle track­ing re­sults will also be shown.  
 
TUPWO020 Error Analysis for C-ADS MEBT2 1925
 
  • H. Geng, Z. Guo, Z. Li, C. Meng, S. Pei, J.Y. Tang
    IHEP, Beijing, People's Republic of China
  
  A local achro­matic scheme has been de­vel­oped for C-ADS MEBT2. This paper pre­sents the error analy­sis re­sults for this MEBT2 scheme. The ef­fects of mag­net and cav­ity mis­align­ment, sta­tic and dy­namic er­rors of elec­tric and mag­netic field, the dis­place­ment of the input beam as well as the ini­tial mis­matches of the in­com­ing beam will be stud­ied. Beam tra­jec­tory cor­rec­tion scheme will also be dis­cussed.  
 
THPWO040 Progress of Injector-1 and Main Linac of Chinese ADS Proton Accelerator 3854
 
  • Y.L. Chi, J. Cao, J.P. Dai, H. Dong, L. Dong, T.M. Huang, X. Jing, S.P. Li, Z. Li, Z.Q. Li, Z.C. Liu, F. Long, Z. Ma, H.F. Ouyang, W.M. Pan, Q.L. Peng, P. Su, Y.F. Sui, J.Y. Tang, J.L. Wang, Q.B. Wang, Q. Ye, Z.S. Zhou
    IHEP, Beijing, People's Republic of China
  
  China ADS study pro­gram was Sup­ported by the "Strate­gic Pri­or­ity Re­search Pro­gram " of the Chi­nese Acad­emy of Sci­ences at 2011, which aims to de­sign and build an ADS demon­stra­tion fa­cil­ity with the ca­pa­bil­ity of more than 1000 MW ther­mal power in about twenty years. The dri­ver Linac is de­fined to be1.5 GeV in en­ergy, 10mA in cur­rent and in CW op­er­a­tion mode. To meet the ex­tremely high re­li­a­bil­ity and avail­abil­ity of ADS, the Linac is de­signed with much in­stalled mar­gin and fault tol­er­ance. ADS ac­cel­er­a­tor is com­posed of two par­al­lel 10MeV in­jec­tors and a main Linac. The su­per­con­duct­ing ac­cel­er­a­tion struc­tures are em­ployed ex­cept the RFQs. This paper will pre­sent de­sign of the China ADS ac­cel­er­a­tor and re­lated key tech­nol­ogy de­vel­op­ments.  
 
THPWO043 Progress on the Physics Design of the C-ADS Injector Scheme I 3863
 
  • Z. Li, P. Cheng, H. Geng, C. Meng, H.F. Ouyang, B. Sun, J.Y. Tang, F. Yan, Z. Yang
    IHEP, Beijing, People's Republic of China
  
  Funding: Surported by China ADS Project
The China ADS (C-ADS) dri­ver linac is com­posed of two par­al­lel 10 MeV in­jec­tors and a main linac which boosts the beam fur­ther to 1.5 MeV. There are two de­sign schemes for the in­jec­tors based on dif­fer­ent work­ing fre­quency and su­per­con­duct­ing cav­ity struc­tures and are under de­vel­op­ing at the same time on IHEP and IMP. The In­jec­tor Scheme I, which is pro­posed by IHEP, works at 325 MHz, the same fre­quency of the main linac, and su­per­con­duct­ing Spoke cav­i­ties with geom­e­try beta of 0.12, the same type of cav­ity as the main linac too, are ap­plied after the RFQ. In this paper, the lat­est progress on physics de­sign will be pre­sented. 		 
 
THPWO044 Error Analysis and Beam Loss Control in C-ADS Main Linac 3866
 
  • C. Meng, Z. Li, J.Y. Tang, F. Yan
    IHEP, Beijing, People's Republic of China
  
  The China ADS (C-ADS) dri­ver linac is de­fined to de­liver a CW pro­ton beam of 1.5 GeV in en­ergy and 10 mA in cur­rent. To meet the ex­tremely high re­li­a­bil­ity and avail­abil­ity, it is very im­por­tant and im­per­a­tive to per­form de­tailed error analy­sis to sim­u­late the real ma­chine, where the er­rors al­ways exist. The error stud­ies are by very in­tense macro-par­ti­cle sim­u­la­tions by both Trace-Win and TRACK codes with space charge ef­fects in­cluded. Through error analy­sis the proper closed-or­bit cor­rec­tion scheme and the max­i­mum tol­er­a­ble hard­ware and align­ment er­rors can be found. This paper pre­sents the method to op­ti­mize the aper­tures of el­e­ments in the C-ADS main linac. Ac­cord­ing to the de­tailed sen­si­tiv­ity analy­sis of dif­fer­ent er­rors, the sta­tic and dy­namic er­rors for the main linac are pro­posed. The basic lat­tice scheme has also been re-op­ti­mized based on the error stud­ies. The cor­rec­tion scheme is also de­scribed, and with the cor­rec­tion scheme the resid­ual orbit can be con­trolled very well. The in­flu­ence of the cor­rec­tors and BPM fail­ures on the cor­rec­tion scheme is also stud­ied.