Author: Liu, K.X.
Paper Title Page
MOPEA038 Coherent Wiggler Radiation of Picosecond CW Electron Beam Produced by DC-SRF Photoinjector 160
  • S. Huang, J.E. Chen, S. Chen, K.X. Liu, S.W. Quan, Zh.W. Wang, X.D. Wen, F. Zhu
    PKU, Beijing, People's Republic of China
  The DC-SRF photoinjector at Peking University is capable of providing CW electron beam with the energy of 3-5 MeV. The beam has high repetition rate, picosecond bunch length and high quality, which can be used to produce high repetition rate THz wave by wiggler radiation. Through off-crest acceleration, electron beam from the injector may be bunched, which will lead to coherent enhancement of the radiation power. With current setup of the DC-SRF injector and a 10-period wiggler, THz radiation power of 10s mW to a few watts can be achieved within the wavelength range of 200 μm to 500 μm. In this work, we will present the calculation results about THz radiation produced by the electron beam from DC-SRF photoinjector. The preparation for the experiments will be also described.  
TUPWA021 Multi-Pass, Multi-Bunch Beam Breakup of ERLs with 9-cell Tesla Cavities 1769
  • S. Chen, J.E. Chen, L.W. Feng, S. Huang, Y.M. Li, K.X. Liu, S.W. Quan, F. Zhu
    PKU, Beijing, People's Republic of China
  Funding: Supported by the Major State Basic Research Development Program of China under Grant No. 2011CB808303 and No. 2011CB808304
In this paper, multi-pass, multi-bunch beam break-up of some small-scale Energy Recovery Linac(ERL) configuration using 9-cell Tesla cavity is discussed. The threshold currents of different cases are investigated and some factors that influence the threshold currents are discussed.
WEPWO028 10×10mm2 MgB2 Film Fabricated by HPCVD as a Candidate Material for SRF Cavit 2375
  • F. He, K.X. Liu, Z. Ni, D. Xie
    PKU, Beijing, People's Republic of China
  • Q. Feng
    Peking University, Beijing, People's Republic of China
  Magnesium diboride (MgB2) is one of candidate material for superconducting radio frequency cavities because of its good features: high transition temperature of ~39K and absence of weak links between grains which prevents other high-Tc superconducting materials, such as YBCO. Previous study of MgB2 are mainly focused on the films’ superconducting properties which are fabricated on Al2O3, SiC or some metal substrates with small scale less than 10×10 mm2. In this work we explore a technique to deposit clean and large-scale MgB2 films on Mo substrate, which is expected to provide a probable way to fabricate MgB2 thin-film cavities.. The measurement results show that its superconducting properties and mechanical behaviors are as good as those fabricated on small-scale metal substrates.  
WEPWO029 Design of a SRF Quarter Wave Electron Gun at Peking University 2378
  • P.L. Fan, K.X. Liu, S.W. Quan, F. Zhu
    PKU, Beijing, People's Republic of China
  Funding: Work supported by National Basic Research Project (No. 2011CB808302) and National Natural Science Funds (No. 11075007)
Superconducting RF electron guns hold out the promise of very bright beams for use in electron injectors, particularly in future high average power free-electron lasers (FELs) and energy recovery linacs (ERLs). Peking University is designing a new SRF gun which is composed of a quarter wave resonator (QWR) and an elliptical cavity. Comparing to the elliptical cavity, the QWR is sufficiently compact at the same frequency and its electric field is quasi-DC. We have finished the preliminary design of the QWR cavity. The simulation shows that multipacting is not a critical issue for our cavity structure. Beam dynamic simulation of the QWR cavity is also presented.
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WEPWO076 Development of Ultra High Gradient and High Q0 Superconducting Radio Frequency Cavities 2474
  • R.L. Geng, W.A. Clemens, J. Follkie, T. Harris, D. Machie, R. Martin, A.D. Palczewski, E. Perry, G. Slack, R.S. Williams
    JLAB, Newport News, Virginia, USA
  • C. Adolphsen, Z. Li
    SLAC, Menlo Park, California, USA
  • J.K. Hao, Y.M. Li, K.X. Liu
    PKU, Beijing, People's Republic of China
  • P. Kushnick
    JLab, Newport News, Virginia, USA
  Funding: Work supported by DOE. Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
We report on the recent progress at Jefferson Lab in developing ultra high gradient and high Q0 superconducting radio frequency (SRF) cavities for future SRF based machines. A new 1300 MHz 9-cell prototype cavity is being fabricated. This cavity has an optimized shape in terms of the ratio of the peak surface field (both magnetic and electric) to the acceleration gradient, hence the name low surface field (LSF) shape. The goal of the effort is to demonstrate an acceleration gradient of 50 MV/m with Q0 of 1010 at 2 K in a 9-cell SRF cavity. Fine-grain niobium material is used. Conventional forming, machining and electron beam welding method are used for cavity fabrication. New techniques are adopted to ensure repeatable, accurate and inexpensive fabrication of components and the full assembly. The completed cavity is to be first mechanically polished to a mirror-finish, a newly acquired in-house capability at JLab, followed by the proven ILC-style processing recipe established already at JLab. In parallel, new single-cell cavities made from large-grain niobium material are made to further advance the cavity treatment and processing procedures, aiming for the demonstration of an acceleration gradient of 50 MV/m with Q0 of 2·1010 at 2K.
The U.S. Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce this manuscript for U.S. Government purposes.