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Xiang, D.

Paper Title Page
TUPMN053 Status of the Photocathode RF Gun at Tsinghua University 1043
 
  • Y.-C. Du, W.-H. Huang, Y. Lin, C.-X. Tang, D. Xiang, L. X. Yan
    TUB, Beijing
 
  The photocathode RF gun at Tsinghua University was built to develop electron source for the Thomson Scattering X-ray source. The main goal is to produce minimum transverse emittance beams with short bunch length at medium charge (~1nC). It includes a 1.6 cell S-band BNL/KEK/SHI type cavity, a solenoid for space charge compensation, a laser system to generate UV light, and different diagnostics tools. In this paper, it will include measurements of the dark current, the charge and quantum efficiency, momentum, transverse electron beam profiles at different locations and the transverse emittance.

This work was supported by the Chinese National Foundation of Natural Sciences under Contract no. 10645002.

 
TUPMN054 Design of a Source to Supply Ultra-fast Electron and X-Ray Pulses 1046
 
  • W.-H. Huang, H. Chen, Y.-C. Du, Hua, J. F. Hua, R. K. Li, Y. Lin, J. Shi, C.-X. Tang, D. Xiang, L. X. Yan, P.-CH. Yu
    TUB, Beijing
 
  In this paper we report the preliminary design and considerations on a multi-discipline ultra-fast source, which is capable of providing the user community with femtosecond electron bunch and light pulses with the wavelength ranging from IR to X-ray. The facility is based on photocathode RF gun driven by a Ti:Sapphire laser system. The low emittance subpicosecond electron bunch at the gun exit can be used in femtosecond electron diffraction setup to visualize the ultrafast structural dynamics. After acceleration and compression, the electron beam with the energy of 50 MeV is further used to provide high peak brightness X-ray by inverse Compton scattering with TW laser. We also consider the possibility and reliability of storing the electron beam in a compact storage ring and the laser pulse in a super-cavity. Operating in this scheme may increase the average flux of the X-ray photons by orders of magnitude.  
TUPMN055 First Principle Measurements of Thermal Emittance for Copper and Magnesium 1049
 
  • D. Xiang, Y.-C. Du, W.-H. Huang, R. K. Li, Y. Lin, C.-X. Tang, L. X. Yan
    TUB, Beijing
  • J. H. Park, S. J. Park
    PAL, Pohang, Kyungbuk
 
  Funding: This work was supported by the Chinese National Foundation of Natural Sciences under Contract no. 10645002.

There are growing interests in generation, preservation and applications of high brightness electron beam. With the rapid development in the techniques for emittance compensation and laser shaping, we are approaching the limit-the uncorrelated thermal emittance. In this paper, we report the measurements of thermal emittance for Cu and Mg. The measurement is conducted in a field-free region. The energy spectrum and angular distribution of the electrons are measured immediately after its emission and further used to reconstruct the initial phase space and the corresponding thermal emittance. We also show how cathode surface roughness* and laser incidence angle as well as its polarization state** affect the quantum efficiency and thermal emittance.

*X. Z. He, High energy physics and nuclear physics,28(2004)1007.**Dao Xiang,et al, NIM A,562(2006)48.

 
TUPMN064 Experimental Approaches for the Beam Dynamics Study in the PC RF Gun at the PAL 1070
 
  • J. H. Park, J. Y. Huang, C. Kim, I. S. Ko, Y. W. Parc, S. J. Park
    PAL, Pohang, Kyungbuk
  • D. Xiang
    TUB, Beijing
 
  Funding: This work is supported in parts by the Center for High Energy Physics at the KNU and the Grant No. R01-2006-000-11309-0 from the Basic Research Program of the Korea Science and Engineering Foundation.

A high-brightness electron beam is emitted from a photo-cathode (PC) RF gun for use in the FIR (Far Infrared) facility being built at the Pohang Accelerator Laboratory (PAL). The beam dynamics study for the PAL XFEL injector is essencial to generate low emittance electron beam from the PC RF gun. The XFEL injector requires 1 nC beam with short bunch length and low emittance. This conditions are simulated with PARMELA code and then are realized on experimental conditions. The experimental conditions for the XFEL injector are measured with beam diagnostic devices such as ICT and Faraday cup for charge measurement, a spectrometer for beam energy measurement. In this article, we present the experimental approaches of the beam dynamics study for the XFEL injector.

wpjho@postech.ac.kr (Jangho Park)

 
FRPMN050 Multiple parameter characterizations for electron beam with diffraction radiation 4096
 
  • D. Xiang, W.-H. Huang
    TUB, Beijing
 
  There are growing interests in developing non-intercepting method for real-time monitoring electron beam parameters for International linear collider and X-ray free electron lasers. In this paper we present both theorectical considerations and experimental demonstration of the ability of diffraction radiation for measuring electron beam profile, divergence, emittance and bunch length*. The possibility of using optical diffraction radiation to direct image electron beam profile is studied**.A new method for bunch length measurement with diffraction radiation deflector is also proposed and analysed***.

* Dao Xiang and Wen-Hui Huang, Nucl. Instr. and Meth. in Phys. Res. B, 254 (2007) 165.** Dao Xiang and Wen-Hui Huang, Nucl. Instr. and Meth. in Phys. Res. A, 570 (2007) 357.*** Dao Xiang and Wen-Hui Huang, Phys. Rev. ST-AB, 10 (2007) 012801.