• C. Kondo, K. Shirasawa
  JASRI/SPring-8, Hyogo-ken
• T. Inagaki, T. Sakurai, T. Shintake
  RIKEN/SPring-8, Hyogo

Low elec­tro-mag­net­ic noise in­ter­fer­ence (EMI) is re­quired to the klystron mod­u­la­tor power sup­ply for XFEL/SPring-8 pro­ject in order to re­al­ize the high­ly sta­ble beam op­er­a­tion with aid of var­i­ous feed­back loops using high-per­for­mance beam mon­i­tors. The dom­i­nant noise source is the thyra­tron switch­ing noise, as­so­ci­at­ed with its rapid volt­age swing of 50 kV max­i­mum. To sup­press the noise leak­age, spe­cial care was taken to the en­clo­sure de­sign of klystron mod­u­la­tor, i.e., using thick steel plates a mono­coque en­clo­sure was fab­ri­cat­ed, in which all of the high power cir­cuits was in­stalled. The rapid image cur­rent flows on the inner sur­face, thus EMI was min­i­mized. A spe­cial co-ax­i­al feed-though was de­vel­oped for fil­ter­ing the con­duct­ed noise on power line for thyra­tron and klystron heaters. In this pre­sen­ta­tion, we will re­port the de­tails of the de­vices and the re­sults of the noise sup­pres­sion.

• T. Inagaki, N. Adumi, T. Hasegawa, H. Maesaka, S. Matsui, T. Sakurai, T. Shintake
  RIKEN/SPring-8, Hyogo
• H. Kimura, C. Kondo, K. Shirasawa
  JASRI/SPring-8, Hyogo-ken

C-band (5712 MHz) ac­cel­er­a­tor is used as the main ac­cel­er­a­tor of the XFEL in SPring-8. Since the C-band gen­er­ates a high ac­cel­er­a­tor gra­di­ent, as high as 35 MV/m, the total length of the 8-GeV ac­cel­er­a­tor fits with­in 400 m, in­clud­ing the in­jec­tor and three bunch com­pres­sors. We use 64 C-band rf units, which con­sists of 128 ac­cel­er­at­ing struc­tures, 64 rf pulse com­pres­sors, 64 klystrons, waveg­uide com­po­nents, etc. Mass-pro­duc­tion of these high power rf com­po­nents has been al­most com­plet­ed. Pro­duc­tion qual­i­ty is con­firmed by the high power rf test. In­stal­la­tion of the C-band com­po­nents start­ed in Au­gust 2009. So far, about half of the com­po­nents have been in­stalled on sched­ule. The ac­cel­er­at­ing struc­tures are aligned with about 0.1 mm ac­cu­ra­cy. By the date of the IPAC'10 con­fer­ence, we will al­most com­plete the in­stal­la­tion. In this pre­sen­ta­tion, we will re­port the con­struc­tion sta­tus.

• T. Shintake, T. Inagaki, C. Kondo, T. Sakurai, K. Shirasawa
  RIKEN/SPring-8, Hyogo

XFEL/SPring-8 will use 72 line type mod­u­la­tor pulse-pow­er sup­ply for 66 C-band klystrons, 4 S-band, one L-band and pulsed 500 kV elec­tron gun. In order to make the size small­er to fit the space avail­able in the high gra­di­ent C-band ac­cel­er­a­tor, we have de­vel­oped all in one box de­sign of mod­u­la­tor. Using metal mono­cok de­sign, filled with oil, it be­comes pos­si­ble to fit all cir­cuit­ry: PFN, thyra­tron, pulse trans­former, klyston sock­et, and pro­tec­tion cir­cuit into a metal box of W 1m x L 1.7m x H 1m, which pro­vides strong sup­port for mas­sive klystron and solenoide with lead shield and func­tions as su­pe­ri­or EM shiled. We de­vel­oped high pre­cis­sion HV charg­er for PFN, which has sta­bil­i­ty bet­ter than 100 ppm.​pp. Mod­u­la­tor and PFN charg­ers are under mass pro­du­tion.

• T. Sakurai, T. Inagaki, C. Kondo, T. Shintake, K. Shirasawa
  RIKEN/SPring-8, Hyogo
• S. Suzuki
  JASRI/SPring-8, Hyogo-ken

We re­port the high power rf test re­sults of C-band ac­cel­er­a­tor sys­tem for X-ray free elec­tron laser (XFEL) in SPring-8 site. In XFEL main ac­cel­er­a­tor, 64 C-band sys­tems will be used in total, whose com­po­nents are under mass pro­duc­tion at sev­er­al in­dus­tries in Japan. We per­formed high power RF test with three sets of the mass-pro­duced com­po­nents in XFEL test bunker. We op­er­ate the C-band com­po­nents with the ac­cel­er­at­ing gra­di­ent, as high as 40 MV/m. We mea­sured the high volt­age break­down rate and the dark cur­rent emis­sion.