• X.H. Yang, C.L. Tian, Y. Yin, T.P. Yu
  National University of Defense Technology, Changsha, Hunan
• Y.Q. Gu
  Laser Fusion Research Center, China Academy of Engineering Physics, Mianyang
• S. Kawata, Y.Y. Ma
  Center for Optical Research and Education, Utsunomiya University, Utsunomiya
• F.Q. Shao
  National University of Defense Technology, Graduate School, Changsha
• H. Xu
  National University of Defense Technology, Parallel and Distributed Processing, Changsha
• M.Y. Yu
  Ruhr-Universität Bochum, Bochum

We have pro­posed a scheme for the gen­er­a­tion of col­li­mat­ed pro­ton beams from the in­ter­ac­tion of an ul­tra-in­tense laser pulse with a rear hole tar­get, which is stud­ied by a 2.5D par­ti­cle-in-cell (PIC) code PLASIM. When an ul­train­tense short laser pulse ir­ra­di­ates on such a tar­get, the hot elec­trons will ex­pand fast into the hole from the inner sur­faces of the hole, and strong lon­gi­tu­di­nal sheath elec­tric field and trans­verse elec­tric field are pro­duced. How­ev­er, the plas­ma in the cor­ners ex­pand slow­er and be com­pressed strong­ly, and then a strong plas­ma jet is sprayed out from the cor­ner with very high speed, which is just like what hap­pened in armor pierc­ing bul­let due to the cu­mu­la­tive en­er­gy ef­fect. The two jets ex­tend into the hole and focus along the axis of the hole. At last, a high qual­i­ty col­li­mat­ed pro­ton beam can be ob­tained near the end of the hole along the prop­a­ga­tion axis. It's found that the beam can prop­a­gate over a much longer dis­tance with­out di­ver­gence. The ef­fect of the hole di­am­e­ter on the col­li­mat­ed pro­ton beam is also in­ves­ti­gat­ed. Such tar­get may serve as an im­por­tant source for col­li­mat­ed pro­ton beam in prac­ti­cal ap­pli­ca­tions.

• C. Sun, J.Y. Li, S.F. Mikhailov, V. Popov, W. Wu, Y.K. Wu
  FEL/Duke University, Durham, North Carolina
• A. Chao
  SLAC, Menlo Park, California
• H. Xu, J. Zhang
  USTC/NSRL, Hefei, Anhui

Tou­schek life­time of an elec­tron beam in a stor­age ring de­pends on the beam po­lar­iza­tion through the in­tra­beam scat­ter­ing ef­fect. Con­se­quent­ly, the elec­tron beam po­lar­iza­tion can be de­ter­mined by com­par­ing the mea­sured Tou­schek life­time of a po­lar­ized beam and an un­po­lar­ized beam. In this paper, we re­port a sys­tem­at­ic ex­per­i­men­tal pro­ce­dure to study the ra­dia­tive po­lar­iza­tion of a stored elec­tron beam. Based upon this tech­nique, we have suc­cess­ful­ly ob­served the po­lar­iza­tion build-up of a 1.15 GeV elec­tron beam in the Duke stor­age ring. Using the Touchek life­time data, we are able to de­ter­mine the equi­lib­ri­um de­gree of the elec­tron beam po­lar­iza­tion and the time con­stant for the po­lar­iza­tion build-up pro­cess.

• G. Feng, W. Fan, W.W. Gao, W. Li, L. Wang, H. Xu, S.C. Zhang
  USTC/NSRL, Hefei, Anhui

HLS (Hefei Light Source) is a ded­i­cat­ed syn­chrotron ra­di­a­tion re­search fa­cil­i­ty, whose emit­tance is rel­a­tive­ly large. In order to im­prove per­for­mance of the ma­chine, es­pe­cial­ly get­ting high­er bril­liance syn­chrotron ra­di­a­tion and in­creas­ing the num­ber of straight sec­tions for in­ser­tion de­vices, an up­grade pro­ject is on going. A new low emit­tance lat­tice, which keeps the cir­cum­fer­ence of the ring no chang­ing, has been stud­ied and pre­sent­ed in this paper. For the up­grade pro­ject, a new ring will be in­stalled on cur­rent ground set­tle­ment of HLS and all of the mag­nets will be re­con­struct­ed. After op­ti­miza­tion, two op­er­a­tion modes have been cho­sen for dif­fer­ent users. Non­lin­ear dy­nam­ics shows that dy­nam­ic aper­ture for on-mo­men­tum and off-mo­men­tum par­ti­cle is large enough. Beam life­time has also been stud­ied. Cal­cu­la­tion re­sults proves that ex­pect­ed beam life­time about 8.5 hours can be ob­tained with a fourth har­mon­ic cav­i­ty op­er­a­tion.

• L. Wang, W. Fan, G. Feng, W.W. Gao, W. Li, H. Xu, S.C. Zhang
  USTC/NSRL, Hefei, Anhui

The Hefei Light Source is com­posed of an 800 MeV stor­age ring, a 200 MeV elec­tron linac and trans­fer line, which was de­signed and con­struct­ed twen­ty years ago. Sev­er­al fac­tors limit the per­for­mance of HLS, for ex­am­ple, less num­ber of in­ser­tion de­vices and large beam emit­tance. To meet the re­quire­ments of syn­chrotron ra­di­a­tion users, an up­grade pro­ject of HLS will be car­ried out in the next two years. Sev­er­al sub-sys­tems will be re­newed, such as mag­net sys­tem, power sup­ply, beam di­ag­nos­tics, vac­u­um sys­tem, etc. The up­grade scheme is de­scribed in this paper, in­clud­ing mag­net lat­tice de­sign, non­lin­ear per­for­mance, col­lec­tive ef­fects,beam in­jec­tion, orbit de­tec­tion and cor­rec­tion, in­jec­tor, etc.

• J.Q. Lan, B. Sun, Y.C. Sun, H. Xu
  USTC/NSRL, Hefei, Anhui

A brief, but clear, re­view of beam po­lar­iza­tion the­o­ry is given in the paper. Par­tic­u­lar­ly, the al­go­rithm of spin lin­ear trans­fer ma­trix (SLIM) is ap­plied to re­mark the sit­u­a­tion of beam in stor­age ring, spe­cif­ic to HLS (Hefei Light Source). The­o­ret­i­cal anal­y­sis in­di­cates that the beam in HLS, work­ing at 800MeV and 2.58/3.58 trans­verse tunes, could keep away from a va­ri­ety of spin res­o­nances, and should be able to build up high po­lar­iza­tion.

• S.C. Zhang, W. Fan, G. Feng, W.W. Gao, H. Geng, Z.G. He, W. Li, L. Wang, H. Xu
  USTC/NSRL, Hefei, Anhui

In order to meet the in­creas­ing re­quire­ments of syn­chrotron ra­di­a­tion users, an up­grad­ing plan of hefei light source is un­der­go­ing by Na­tion­al Syn­chrotron Ra­di­a­tion Lab­o­ra­to­ry (NSRL). The emit­tance of stor­age ring is re­duced from 166nm.​rad to 36nm.​rad. In this paper, we study the beam close orbit dis­tor­tions' (COD) sen­si­tiv­i­ty to the field and align­ment er­rors in mag­nets. Es­ti­ma­tion of the COD from var­i­ous error sources is in­ves­ti­gat­ed. The dis­tri­bu­tion of beam po­si­tion mon­i­tors and the lo­ca­tion of cor­rec­tors are re­port­ed in the paper. Sim­u­la­tion proves that COD can be cor­rect­ed down to 50 mi­crons level. In the same time the cor­rec­tor strengths are weak­er enough in the cor­rec­tion scheme.

• S.C. Zhang, W. Fan, G. Feng, W.W. Gao, W. Li, L. Wang, H. Xu
  USTC/NSRL, Hefei, Anhui

To en­hance the per­for­mance of Hefei Light Source, an up­grade pro­ject is un­der­go­ing. The mag­net lat­tice of stor­age ring will be re­con­struct­ed with 4 DBA cells, whose ad­van­tages are lower beam emit­tance and more straight sec­tion avail­able for in­ser­tion de­vices. In order to as­sure smooth beam ac­cu­mu­la­tion pro­cess under new low emit­tance lat­tice, the in­jec­tor, which is com­posed of elec­tron linac and beam trans­fer line, would be up­dat­ed. The de­tail of up­grad­ing Hefei Light Source trans­port line will be de­scribed in this paper. It in­clude the up­grad­ing of lat­tice, the orbit con­trol of beam trans­fer line and oth­ers. It is hope­ful to re­al­ize a high trans­fer ef­fi­cien­cy and high in­jec­tion ef­fi­cien­cy for new lower beam emit­tance stor­age ring.