Zhao K.

Paper	Title	Page
MO101	The growth of SRF in China	1
	J. E. Chen, K. Zhao IHIP, Peking University
	The RF Superconductivity was first explored in China by Dr. Ding Yu of IHEP in early 1970's. Unfortunately the research was stopped for about 10 years after Dr. Ding passed away, until the first SRF laboratory was founded at Peking University by the end of 1980's. The early efforts of PKU SRF group on the design and fabrication of L-band high beta cavities using China-made niobium sheets as well as on developing Nb-Cu sputtering technology to construct SRF QWR as a post Tandem accelerator are described. The "SRF accelerator based FEL light source" project, which was proposed by PKU SRF group and joined by IHEP & SIAP, was formally approved by MOST in 2003 as a national key project of basic research. A series of work around the project carried out at PKU, including the construction and feasibility test of the DC-SC photo-injector, the R&D of multi-cell Nb cavities and cavities of large grain Nb are presented. Progresses of IHEP SRF group in developing SRF infrastructures and two 500Hz single-cell cavities for BEPCII as well as studies on 1.3 GHz & 700 MHz single cell cavities for proton acceleration are reported. Efforts made at CIAE on fabricating low beta Nb-Cu SRF QWR for heavy ion post acceleration and R&D activities in developing SRF technology for SSRF at SIAP are also presented. A growing phase of SRF in China is emerging.
	Slides(PDF)
TUP84	Introduction of 9-cell Accelerator at Peking University	350
	Z. C. Liu, S. W. Quan, F. Zhu, X. Y. Lu, B. C. Zhang, F. S. He, J. Dai, S. Jin, W. C. Xu, J. K. Hao, K. Zhao, J. E. Chen IHIP, Peking University
	The 9-cell superconducting accelerator module of Peking University (PKU) is in the end of factory check and will be constructed very soon. It will be the first home-made 9-cell superconducting accelerator module at Peking University and in China. As the main part of the PKU ERL and FEL project, it is composed of one 9-cell superconducting cavity, liquid helium tank, liquid nitrogen tank, tuning system, power coupler, suspending device, magnetic shielding, measurement and control device. This paper will give a brief description of the 9- cell accelerator module.
WE103	Study on the 3.5-cell DC-SC Photo-injector	367
	W. C. Xu, F. Zhu, S. W. Quan, K. Zhao IHIP, Peking University
	In order to get high quality electron beam for PKUERL- FEL project. A 3.5-cell DC-SC photo-injector was designed and optimized. The pierce gun and 3.5-cell superconducting Nb cavity are DC acceleration section and RF acceleration section, respectively. A tuner for the whole 3.5-cell superconducting cavity has been designed. The beam parameters of 3.5-cell DC-SC photo-injector are also presented in this paper. The disadvantage and problem of 1.5-cell DC-SC photo cathode injector which was for principle demonstration have been overcame in the design of 3.5-cell DC-SC photo cathode injector.
	Slides(PDF)
WEP12	Design of the compact high average current DC-SC photoinjector at Peking University	461
	F. Zhu, S. W. Quan, W. C. Xu, J. K. Hao, Z. C. Liu, K. Zhao, B. C. Zhang IHIP, Peking University
	A new compact high average current DC-SC photoinjector has been designed at Peking University. The main Part of the injector consists of a DC pierce gun and a 3+1/2cell superconducting cavity. The optimization of the DC gun and superconducting cavity are presented in this paper. The simulation results show that the new injector can provide high average current electron beams with bunch charge of 100pc, cw (or high repetition rate mode) operation, transversal emittance lower than 2 mm-mrad and bunch length of 4 ps.
WEP65	Study on the buffered electropolishing Jacquet layers on niobium cavity	660
	E. D. Wang, T. M. Xin, X. Y. Lu, L. M. Yang, L. Lin, S. Jin, K. Zhao IHIP, Peking University
	Buffered electropolishing on niobium cavities has been developed at Peking University. Some small niobium samples have been polished very smoothly. An experiment has demonstrated that both of the liquid and solid Jacquet layers exist on the surface of anode simultaneously. The results of experiment, that more than 70% voltage is taken by the Jacquet layers, show us that the cathode shape is not a necessary condition for polishing the dumbbell. Flat cathode is available to polish the dumbbell. We have observed though the experiment that the different fluid liquid Jacquet layer movements could cause the different results on the dumbbell surface. These studies show that BEP can offer a smooth surface on niobium cavities.
WEP86	Niobium sample surface treatment by buffered electropolishing	724
	S. Jin, L. Lin, L. M. Yang, E. D. Wang, T. M. Xin, X. Y. Lu, K. Zhao IHIP, Peking University
	The electrolyte of buffered electropolishing (BEP) is consisted of hydrofluoric, sulfuric and lactic acids. In the present work, the process of BEP has been familiarized and the main parameters were investigated. It was demonstrated that the polishing rate of BEP had a linear relationship with current density; therefore the polishing rate can be controlled via current density, which make the control of BEP easier. Through inspection using a metallographic optical microscope (MOM) and an Atomic Force Microscope (AFM), it is proved that Nb surfaces treated by BEP were much smoother than those treated by the electropolishing (EP) process widely used in the superconducting radio frequency community.