Author: Yan, L.X.
Paper Title Page
MOPPP008 Hard X-ray Generation Experiment at Tsinghua Thomson Scattering X-Ray Source 583
  • Y.-C. Du, H. Chen, Q. Du, Hua, J.F. Hua, W.-H. Huang, H.J. Qian, C.-X. Tang, H.S. Xu, L.X. Yan, Z. Zhang
    TUB, Beijing, People's Republic of China
  Recently, there is increasing industrial and scientific interesting in ultra-fast, high peak brightness, tunable energy and polarization, monochromatic hard X-ray source. The X-ray source based on the Thomson scattering between the relativistic electron beam and TW laser pulse is the suitable candidate for its compact and affordable alternatives for high brightness hard monochromatic X-ray generation. Accelerator laboratory in Tsinghua University al so proposed and built Tsinghua Thomson scattering X-ray source. The hard x-ray pulse has been generated in experiment with 47 MeV electron and 20 TW laser in this year, and the parameters of the X-ray have been measured preliminarily. The experimental results are presented and discussed in this paper.  
MOPPP009 X-Ray Spectra Reconstruction of Thomson Scattering Source From Analysis of Attenuation Data 586
  • Y.-C. Du, Hua, J.F. Hua, W.-H. Huang, C.-X. Tang, H.S. Xu, L.X. Yan, H. Zha, Z. Zhang
    TUB, Beijing, People's Republic of China
  Thomson scattering X-ray source, in which the TW laser pulse is scattered by the relativistic electron beam, can provide ultra short, monochromatic, high flux, tunable polarized hard X-ray pulse which is can widely used in physical, chemical and biological process research, ultra-fast phase contrast imaging, and so on. Since the pulse duration of X-ray is as short as picosecond and the flux in one pulse is high, it is difficult to measure the x-ray spectrum. In this paper, we present the X-ray spectrum measurement experiment on Tsinghua Thomson scattering. The preliminary experimental results shows the maximum X-ray energy is about 47 keV, which is agree well with the simulations.  
TUPPD069 Schottky-Enabled Photoemission and Dark Current Measurements - Toward an Alternate Approach to Fowler-Nordheim Plot Analysis 1563
  • E.E. Wisniewski, W. Gai, J.G. Power
    ANL, Argonne, USA
  • H. Chen, Y.-C. Du, Hua, J.F. Hua, W.-H. Huang, C.-X. Tang, L.X. Yan, Y. You
    TUB, Beijing, People's Republic of China
  • A. Grudiev, W. Wuensch
    CERN, Geneva, Switzerland
  • E.E. Wisniewski
    Illinois Institute of Technology, Chicago, Illinois, USA
  Field-emitted dark current, a major gradient-limiting factor in RF cavities, is usually analyzed via Fowler-Nordheim (FN) plots. Traditionally, field emission is attributed to geometrical perturbations on the bulk surface whose field enhancement factor (beta) and the emitting area (A) can be extracted from the FN plot. Field enhancement factors extracted in this way are typically much too high (1 to 2 orders of magnitude) to be explainable by either the geometric projection model applied to the measured surface roughness or by field enhancement factors extracted from Schottky-enabled photoemission measurements. We compare traditional analysis of FN plots to an alternate approach employing local work function variation. This is illustrated by comparative analysis of recent dark current and Schottky-enabled photoemission data taken at Tsinghua S-band RF gun. We conclude by describing a possible experimental plan for discrimination of variation of local work function vs. local field enhancement.