1、BEPCII LinacPei Guoxifor the BEPCII-Linac GroupInstitute of High Energy PhysicsChinese Academy of Sciences Progress of the BEPCII Linac Commissioning ( 4thIMAC )Date 1BEPCII LinacThe Committee suggests paying particular attention to the following details in 3rdIMAC and our responses In order to obta
2、in the specified 2degrees RF phase stability, a temperature stabilized reference drive line needs to be established with a temperature coefficient of 0.1 degree per C.The reference lines temperature coefficient is 5ppm/C, and will be stabilized with cooling water within 0.2C. Measuring and adjusting
3、 the RF phase with respect to the beam is not planned, but appears to be desirable. Based on some experiences, the beam induced signals are not so clear and so stable, hence the energy maximum method is adopt to set the right RF phase. The Committee encourages the LINAC team to exercise the transpor
4、t of the full energy beam into the injection channel as early as possible to preserve some flexibility within the tight schedule in case of unforeseen problems.Yes, this will be done soon.Date 2BEPCII Linac The Committee would like to encourage the BEPC-II team to try to accommodate the full sub-har
5、monic bunching systems program or at least keep it as a high priority valuable upgrade option. The potential benefit may not only be the slightly increased injection efficiency but these systems may also contribute significantly to providing tolerable condition for the colliding beam detector during
6、 top-up operation. It is planning to apply the budget, and may finish the technical design by full 2005, construction in 2006, be measured and RF conditioned in the 1st half 2007 and will be installed in the tunnel in summer 2007. With regard to operations, the Committee would like to mention that a
7、 single spare klystron might not be sufficient to provide the high machine availability necessary for the anticipated top-up mode. The Committee suggests to re-assess the probability for system failures based on BEPC-I linac and SLAC linac operations.It is planed to make each 45-50 MW klystron be op
8、erated at 35-40 MW output, then two spare klystron may be possible; as a back-up version, one more SLAC-65 MW klystron may be prepared to instead of one 45-50 MW klystron and keep the total 16 klystron constant.Date 3BEPCII LinacContents1. Sub-systems upgrade progress2. Machine commissioning3. Probl
9、emsDate 4BEPCII Linac1.1 Pre-injector 1. New electron gun (done)2. Bunching, RF system 1. Sub-systems upgrade progressDate 5BEPCII Linac200Kv High voltage station LINACElectron gunNew electron gunDate 6BEPCII LinacDate 7BEPCII LinacGun controller & power supply Gun Gun HV ModulatorDate 8BEPCII Linac
10、Design MeasureFrequency 2856MHz 2856MHz Waveguide power divider1） VSWR 1.052） Imbalance 0.2dB3） Directivity 26dB1） VSWR 1.0382） Imbalance 0.05dB3） Directivity 29dB VSWR 1.2 1.2 Attenuation 0 25 dB 0 35 dB Phase shift 0 360 0 360 Mid-power attenuator / phase-shifter used for pre-buncherBunching, RF systemDate 9BEPCII LinacDesign MeasureFrequency 2856MHz Waveguide power divider1） VSWR 1.052） Imbalance 0.2dB3） Directivity 26dBVSWR 1.2 Attenuation 0 25 dB Phase shift 0 360 High-power attenuator / phase-shifterfor buncherDate 10
