Author: Gao, J.
Paper Title Page
TUPEA017 Monoenergetic Electron Beams with Ultralow Normalized Emittance Generated from Laser-Gas Interaction 1196
 
  • D.Z. Li, J. Gao, K. Huang, J. Jiarui, Y. Ma
    IHEP, Beijing, People's Republic of China
  • L.M. Chen, W.C. Yan
    Institute of Physics, Chinese Academy of Sciences, Beijing, People's Republic of China
 
  High quality electron bunches are generated by using 2 TW, 80 fs, high contrast laser pulses interacting with helium gas targets. In optimized condition, we get tens MeV monoenergetic electron beams with small energy spread and the normalized emittance 0.07π mm·mrad. Due to its ultra small emittance and high initial energy, such bunch is very suitable for high current linear accelerators.  
 
TUPME021 Optimization Parameter Design of a Circular e+e Higgs Factory 1616
 
  • D. Wang, Y.W. An, J. Gao, H. Geng, Y.Y. Guo, Q. Qin, N. Wang, S. Wang, M. Xiao, G. Xu, S.Y. Xu
    IHEP, Beijing, People's Republic of China
 
  Funding: NSFC:11175192
In this paper we will show a genral method of how to make an optimized parameter design of a circular e+e Higgs Factory by using analytical expression of maximum beam-beam parameter and beamstrahlung beam lifetime started from given design goal and technical limitations. A parameter space has been explored.
 
 
TUPME022 Study on the Single Bunch Transverse Emittance Growth in BAPS 1619
 
  • J. Gao, D. Wang
    IHEP, Beijing, People's Republic of China
 
  Funding: Supported by the National Foundation of Natural Sciences Contract 11175192.
Beijing Advanced photon Source (BAPS) is a proposed next synchrotron radiation facility which has much smaller transverse emittance after SSRF in China, with 5 GeV energy and 1.5 km circumference. In order to explore how small the transverse emittance we can get on BAPS, this paper studies the single bunch transverse emittance growth due to short range wakefield according to J. Gao’ theory. The mechanism of wakefield induced single bunch emittance is explained first and then the transverse emittance at the design beam current is estimated. Also, the tolerances for the transverse loss factor and the vacuum chamber misalignment (or the closed orbit distortion) are presented.
 
 
TUPME024 Re-optimization of the Final Focus System Optics with Vertical Chromatic Correction 1622
 
  • Y. Wang, J. Gao
    IHEP, Beijing, People's Republic of China
  • P. Bambade
    LAL, Orsay, France
 
  Funding: The France China Particle Physics Laboratory (FCPPL) and The National Natural Science Foundation of China (NSFC, Project 11175192)
The purpose of the final focus (FF) system of the future linear collider (ILC and CLIC) is to demagnify the beam to the required size at the IP. This can be done in a compact way based on a local chromaticity correction. Two important issues are beam-beam induced radiation effects and the optical correction strategy to mitigate static and dynamic imperfections. For a small enough beam energy spread, we investigate the possibility to get a smaller vertical beam size, at the expense of a larger horizontal beam size, by re-optimising the final focus optics with chromatic correction mainly in the vertical plane. Firstly, we track the beam with MAD-X, with and without chromaticity correction, to estimate the optimum betax and betay values by rematching the linear optics, and cross-check and improve the rematching procedure with MAPCLASS. Then, we study the original design and an alternative simplified optical system, using a set of enlarged betax values, and optimize the sextupoles as a function of betay to minimize the vertical beam size for different assumptions on the energy spread.
 
 
TUPWO017 Simulation on the Breaking of αx Multiknob Orthogonality in the Presence of Gradient and Coupling Errors and Experimental Investigation 1919
 
  • S. Bai, J. Gao
    IHEP, Beijing, People's Republic of China
  • P. Bambade
    LAL, Orsay, France
  • G.R. White
    SLAC, Menlo Park, California, USA
 
  The ATF2 project is the final focus system prototype for ILC and CLIC linear collider projects, with a purpose to reach a 37nm vertical beam size at the interaction point. In beam tuning towards the goal beam size, the presence of a tilt of the IP Shintake monitor fringe pattern with respect to the x-y coordinate system of the beam can break the orthogonality in the main σ34 and σ32 waist corrections required to reduce the vertical beam size at IP. Concerning the method of doing αx scan and measuring the vertical beam size to diagnose the IPBSM fringe tilt or residual σ13, one thing should be studied is to check what could break the orthogonality of the αx knob other than σ13 and the IPBSM fringe tilt. In this paper, we report on the simulation study that check for the breaking of orthogonality of the αx knob in the presence of gradient and coupling errors; to what extent this breaking of orthogonality can go; and also calculate the IPBSM fringe tilt angle from experiment results.  
 
WEPWO018 Status of the IHEP 1.3 GHz Superconducting RF Program for the ILC 2355
 
  • J. Gao, Y.L. Chi, J.P. Dai, R. Ge, T.M. Huang, S. Jin, C. H. Li, S.P. Li, Z.Q. Li, H.Y. Lin, Y. Liu, Z.C. Liu, Q. Ma, Z.H. Mi, W.M. Pan, Y. Sun, J.Y. Zhai, T.X. Zhao, H.J. Zheng
    IHEP, Beijing, People's Republic of China
 
  The 1.3 GHz superconducting radio-frequency (SRF) technology is one of the key technologies for the ILC. IHEP is building an SRF Accelerating Unit, named the IHEP ILC Test Cryomodule (IHEP ILC-TC1), for the ILC SRF system integration study, high power horizontal test and possible beam test in the future. In this paper, we report the components test results and the assembly preparation of this cryomodule. Processing and vertical test of the large grain low-loss shape 9-cell cavity is done. Performance of the in-house made high power input coupler and tuner at room temperature reaches the ILC specification.  
 
WEPWO019 Development of Frequency Measurement Setup for ADS 650MHz and 1.3GHz Superconducting RF Cavities at IHEP 2358
 
  • S. Jin, J. Gao, Y. Liu, Z.C. Liu, J.Y. Zhai, T.X. Zhao, H.J. Zheng
    IHEP, Beijing, People's Republic of China
 
  The Accelerator Driven Sub-critical System (ADS) is under development in China, and the 650MHz β=0.82 superconducting RF cavity (SRF) has been chosen as a possible candidate to accelerate the proton bunches in the medium energy section from 360MeV to 1.5GeV [1]. In order to obtain quality management and quality assurance during fabrication, radio frequency measurements on parts and subassemblies of SRF cavities become a proper method [2]. In this paper, study on developing a new frequency measurement setup mainly for half cells, dumb-bells and end groups of ADS650MHz cavities at IHEP was reported. A digital pressure sense was assembled in the setup. Together with the simulation on the structural and frequency by ANSYS Workbench, a quantitative standard for the frequency measurement was built for the cavity fabrication. Since a 9-cell TESLA-Like cavity is also under study in the meantime, via a slight modification, the setup can be also used for it.  
 
WEPWO021 ADS 650MHz β=0.82 Supercongducting Cavity Research Status 2361
 
  • Z.C. Liu, J. Gao, S. Jin, Y. Liu, J.Y. Zhai, T.X. Zhao, H.J. Zheng
    IHEP, Beijing, People's Republic of China
  • J.X. Wang, H. Yu, H. Yuan
    BIAM, Beijing, People's Republic of China
 
  IHEP is developing a 650MHz β=0.82 supercongducting cavity for the China ADS project. The cavity is for the energy range of from 367MeV to 1500Mev. We have chosen a five cell cavity and optimized the cavity with Epk/Eacc and Bpk/Eacc to reach high gradient. Two cavity parts were fabricated and the EB welding is in process. This paper will show the fabrication status and measurement results.  
 
WEPWO022 IHEP03 Fabrication and Testing Status 2364
 
  • Z.C. Liu, J. Gao, S. Jin, Y. Liu, J.Y. Zhai, T.X. Zhao, H.J. Zheng
    IHEP, Beijing, People's Republic of China
  • J.X. Wang, H. Yu, H. Yuan
    BIAM, Beijing, People's Republic of China
 
  IHEP is developing RF superconducting technology with different type of superconducting cavities. Tesla-like cavity which is designed by KEK is one of them. We have fabricated all the parts of the cavity using Nb material from Ningxia and cavity welding will be started soon. This paper will show the cavity fabrication procedures and measurement results.  
 
WEPWO023 High Current Superconducting Cavity Study and Design 2366
 
  • Z.C. Liu, J. Gao, S. Jin, Y. Liu, J.Y. Zhai, T.X. Zhao, H.J. Zheng
    IHEP, Beijing, People's Republic of China
  • F. Wang
    PKU, Beijing, People's Republic of China
 
  Funding: Project 11275226 supported by NSFC
IHEP is developing a new type of high current superconducting cavity called slotted cavity proposed in 2010. The cavity is suitable for accelerating high beam current in Energy Recovery Linac (ERL). The cavity can extremely dump high order modes (HOMs) in the cavity to keep a high beam current threshold in the linac. We have studied and designed a three cell cavity and the fabrication is under going.
 
 
WEPWO026 HOM Parameters Simulation and Measurement Result of the IHEP02 Low-loss Cavity 2372
 
  • H.J. Zheng, J. Gao, S. Jin, Y. Liu, Z.C. Liu, Z.H. Mi, J.Y. Zhai, T.X. Zhao
    IHEP, Beijing, People's Republic of China
  • H. Yuan
    BIAM, Beijing, People's Republic of China
 
  In cavities , there exists not only the fundamental mode which is used to accelerate the beam but also higher order modes(HOMs). The higher order modes excited by beam can seriously affect beam quality, especially for the higher R/Q mode. This paper reports on recent measurements of higher order modes in the IHEP-2 low-loss SRF cavity. Using different methods, the Qext of the dangerous modes passband are got. This result is compared with TESLA result. R/Q of the first three passbands are also got by CST and compared with the results of TESLA cavity and STFBaseline cavity.  
 
WEPEA022 Analytical Estimations of the Dynamic Apertures of Beams with Momentum Deviation and Application in FFAG 2546
 
  • M. Xiao, J. Gao
    IHEP, Beijing, People's Republic of China
 
  Analytical formulae for estimating the dynamic apertures of synchrotron particles has been well established. Based on the standard mapping, we extend the analytical formulae of dynamic aperture for off-momentum particles in circular accelerator. And we compare the analytical results with the simulation ones in the BEPC-II positron ring lattice under some conditions. What's more, we give the analytical formulae of dynamic aperture for FFAG in the similar way.  
 
THPME010 Magnetic Shielding for the 1.3 GHz Cryomodule at IHEP 3528
 
  • S. Jin, Y. Chen, J. Gao, R. Ge, Y. Liu, Z.C. Liu, J.Y. Zhai, T.X. Zhao, H.J. Zheng
    IHEP, Beijing, People's Republic of China
  • F. Yang
    China Iron and Steel Research Institute Group, Beijing, People's Republic of China
 
  An ILC-type Superconducting RF (SRF) accelerating unit is being studied at IHEP. In order to achieve the design performance including both accelerating gradient and quality factor, the SRF cavity must be cooled with ambient magnetic field well shielded to the level of several mG[1,2]. In this paper, permeability of several kinds of materials for magnetic shielding made in China is systematically studied in cooperation with China Iron & Steel Research Institute Group (CISRI) and reported for the first time. By using proper material, numerical calculation for the magnetic shielding design was done via the program of Opera-3D, and then magnetic shield was fabricated by CISRI. This paper will show those studies above and the final magnetic shielding effect at room temperature. Comparisons between simulation result and real effect will also be discussed in the paper, as well as the preliminary analysis for the magnetic field leaking of this design.