• J. Yamazaki, A. Enomoto, Y. Kamiya
  KEK, Ibaraki

One of the most im­por­tant is­sues for ERL in­jec­tors is to gen­er­ate elec­tron beams with ul­tra-low emit­tance and to ac­cel­er­ate the beams through the in­jec­tor with­out emit­tance growth. For this pur­pose, we have de­vel­oped an ef­fi­cient sim­u­la­tion code to in­ves­ti­gate the mech­a­nism of emit­tance growth due to space charge ef­fect and to ex­ploit its sup­pres­sion method. In this code, the lon­gi­tu­di­nal mo­tion is treat­ed by the one-di­men­sion­al dif­fer­ence equa­tions for macro-par­ti­cles, while the ra­di­al mo­tion is solved by the en­ve­lope equa­tions for the pieces of sliced bunch. We find that the total emit­tance takes a min­i­mum when all el­lipses of sliced en­ve­lope have the same di­rec­tion on the a-a' plane, where a is the am­pli­tude of sliced en­ve­lope and a' its deriva­tive along the lon­gi­tu­di­nal di­rec­tion. The pa­ram­e­ters of a 5 MeV in­jec­tor were op­ti­mized by this code, as­sum­ing that the volt­age of the DC elec­tron gun is 330 kV and the ini­tial par­ti­cle dis­tri­bu­tion at the exit of the gun has a uni­form el­lipse. Even for such a low volt­age gun, we ob­tained a min­i­mum value of the rms nor­mal­ized emit­tance, 0.10 mm, and the rms bunch length, 0.83 mm, the val­ues of which were cal­cu­lat­ed by using PARMELA.

• T. Tanikawa
  Sokendai - Okazaki, Okazaki, Aichi
• M. Adachi, M. Katoh, J. Yamazaki, H. Zen
  UVSOR, Okazaki
• M. Hosaka, Y. Taira, N. Yamamoto
  Nagoya University, Nagoya

Light source tech­nolo­gies based on laser seed­ing are under de­vel­op­ment at the UVSOR-II elec­tron stor­age ring. In the past ex­per­i­ments, we have suc­ceed­ed in gen­er­at­ing co­her­ent DUV (Deep Ul­tra-Vi­o­let) har­mon­ics with var­i­ous po­lar­iza­tions. A spec­trum mea­sure­ment ex­per­i­ment of CHG (Co­her­ent Har­mon­ic Gen­er­a­tion) was car­ried out by using a spec­trom­e­ter of from vis­i­ble to DUV range. In order to di­ag­nose spec­tra of short­er-wave­length CHG, a spec­trom­e­ter for VUV (Vac­u­um Ul­tra-Vi­o­let) has been con­struct­ed and the VUV CHG was mea­sured. In ad­di­tion, we try to use a seed­ing light source based on not only fun­da­men­tal of Ti: Sap­phire laser and the har­mon­ics gen­er­at­ed from non-lin­ear crys­tals but also HHG (High Har­mon­ic Gen­er­a­tion) in a gas for the CHG ex­per­i­ment. Now the HHG sys­tem is under de­vel­op­ment. In this pre­sen­ta­tion, we in­tro­duce the VUV spec­tral mea­sure­ment sys­tem and the HHG sys­tem and also re­port about com­par­i­son be­tween the re­sults of the cur­rent CHG ex­per­i­ments and de­sign stud­ies of nu­mer­i­cal cal­cu­la­tion for them.

• H. Zen, K. Hayashi, J. Yamazaki
  UVSOR, Okazaki
• M. Adachi, M. Katoh, T. Tanikawa, H. Zen
  Sokendai - Okazaki, Okazaki, Aichi
• M. Hosaka, Y. Taira, N. Yamamoto
  Nagoya University, Nagoya

UVSOR-II is a low emit­tance, 750 MeV syn­chrotron light source. Low emit­tance and low en­er­gy syn­chrotron light sources nat­u­ral­ly suf­fered from short elec­tron life­time due to Tou­schek ef­fect. Top-up op­er­a­tion is a so­lu­tion for over­com­ing the ef­fect. In the UVSOR-II, tri­als of mul­ti-bunch top-up op­er­a­tion at the full en­er­gy were start­ed from 2008. In the tri­als, we have suc­ceed­ed in keep­ing the stored beam cur­rent around 300 mA for 12 hours. From this fis­cal year, sin­gle bunch in­jec­tion was start­ed for sin­gle bunch user op­er­a­tions and for ex­per­i­ments on ad­vanced light source de­vel­op­ment such as Free Elec­tron Laser (FEL), Co­her­ent Syn­chrotron Ra­di­a­tion (CSR), Co­her­ent Har­mon­ic Gen­er­a­tion (CHG), which re­quire sin­gle bunch or 2-bunch fill­ing op­er­a­tion. We have al­ready per­formed sin­gle bunch top-up op­er­a­tion in user time with the stored beam cur­rent of 50 mA. And FEL las­ing with top-up op­er­a­tion was also achieved at the laser wave­length of 215 nm with the stored beam cur­rent of 130 mA / 2-bunch. In the FEL las­ing ex­per­i­ment, we suc­ceed­ed in keep­ing the av­er­age power of FEL around 130 mW for three hours.

• M. Adachi, K. Hayashi, M. Katoh, S.I. Kimura, J. Yamazaki, H. Zen
  UVSOR, Okazaki
• M. Hosaka, Y. Taira, Y. Takashima, N. Yamamoto
  Nagoya University, Nagoya
• T. Takahashi
  KURRI, Osaka
• T. Tanikawa
  Sokendai - Okazaki, Okazaki, Aichi

UVSOR, a 750 MeV syn­chrotron light source of 53m cir­cum­fer­ence had been op­er­at­ed for more than 20 years. After a major up­grade in 2003, this ma­chine was re­named to UVSOR-II. The ring is now rou­tine­ly op­er­at­ed with low emit­tance of 27 nm-rad and with four un­du­la­tors. By uti­liz­ing a part of the ex­ist­ing FEL sys­tem and an ul­tra-short laser sys­tem, co­her­ent syn­chrotron ra­di­a­tion in THz range and co­her­ent har­mon­ic gen­er­a­tion in VUV range have been ex­ten­sive­ly stud­ied under in­ter­na­tion­al col­lab­o­ra­tions. Based on re­sults ob­tained from pre­vi­ous co­her­ent light source de­vel­op­ments, a new five-year re­search pro­gram on the co­her­ent light source de­vel­op­ments has been start­ed from FY2008, which in­cludes cre­ation of a new 4-m long straight sec­tion by mov­ing the in­jec­tion point, up­grades of the un­du­la­tor and the laser sys­tem and con­struc­tion of ded­i­cat­ed beam-lines for these co­her­ent light sources. Pre­sent sta­tus and up­grade plan on these co­her­ent light sources at UVSOR-II will be pre­sent­ed at the con­fer­ence.