Author: Deng, H.X.
Paper Title Page
MOPME049 Status of Non-destructive Bunch Length Measurement based on Coherent Cherenkov Radiation 583
  • H.X. Deng, S.L. Lu, T. Yu, J.B. Zhang
    SINAP, Shanghai, People's Republic of China
  • G.A. Naumenko, A. Potylitsyn, M.V. Shevelev, D.A. Shkitov
    TPU, Tomsk, Russia
  Funding: This work was supported by the joint Russian-Chinese grant (RFBR 110291177 and NSFC 11111120065) and partially by the Program of Russian MES “Nauka” and the Chinese NSFC 11175240.
As a novel non-destructive bunch length diagnostic of the electron beam, an experimental observation of the coherent Cherenkov radiation generated from a dielectric caesium iodide crystal with large spectral dispersion was proposed for the 30MeV femtosecond linear accelerator at Shanghai Institute of Applied Physics (SINAP). In this paper, the theoretical design, the experimental setup, the terahertz optics, the first angular distribution observations of the coherent Cherenkov radiation, and the future plans are presented.
* Shevelev M. et al., Journal of Physics: Conf. Ser. 357 (2012) 012023.
MOPME067 Non-Invasive Bunch Length Diagnostics Based on Interferometry From Double Diffraction Radiation Target 631
  • D.A. Shkitov, G.A. Naumenko, A. Potylitsyn, M.V. Shevelev
    TPU, Tomsk, Russia
  • H.X. Deng, S.L. Lu, T. Yu, J.B. Zhang
    SINAP, Shanghai, People's Republic of China
  Funding: This work was supported by the joint Russian-Chinese grant (RFBR 110291177 and NSFC 11111120065) and partially by the Program of Russian MES “Nauka” and the SINAP Xinrui Program Y15501A061.
Reliable and precise non-invasive beam diagnostics technique to measure length of sub-picosecond electron bunches are required for new accelerator facilities (FEL, et al.). Investigations of coherent radiation generated by such bunches using different interferometers allow to determine a bunch length*. Measuring a dependence of radiation yield intensity from two DR targets on a distance between them (the intrinsic DR interferogram), it is possible to obtain the same information. Such a non-invasive technique can be directly used for ultra-short bunch length measurements. Recently the first experiment with a double DR target was carried out at the SINAP fs linac facility** with parameters described in***. The double DR target was consisted of two plates made from Al foil. The pyro-electric detector SPI-D-62 was used. Here we report the results of the second stage of our investigations. The DR interferograms of different electron bunch length were measured. The bunch length was reconstructed using the heuristic model based on the dimension theory and simulation data. We compare the results from DR interferograms and Michelson interferometer measurements and show their similarity.
*Murokh A. et al., NIMA 410 (1998) 452.
**Zhang J.B., Shkitov D.A. et al., IBIC’12 MOPB65 (2012).
***Lin X., Zhang J. et al., Chin. Phys. Let. V. 27 N. 4 (2010) 044101.
TUPEA030 High Brightness and Fully Coherent X-ray Pulses from XFELO Seeded High-gain FEL Schemes 1214
  • H.X. Deng, C. Feng
    SINAP, Shanghai, People's Republic of China
  The successful operation of the hard x-ray self-seeding experiment at the LCLS opens the era of fully coherent hard x-ray free electron lasers (FELs). However, the shot-to-shot radiation fluctuation is still a serious issue. In this paper, high-gain, single-pass x-ray FEL schemes seeded by the narrow bandwidth radiation signal from an x-ray FEL oscillator were proposed and investigated, which are expected to generate high brightness, fully coherent and stable x-ray pulse. A simple model has been developed to figure out the temporal and the spectral structures of the output pulses in x-ray FEL oscillator. And options using two synchronized accelerators and using one accelerator were considered, respectively.  
TUPEA042 Linac Design for Dalian Coherent Light Source 1226
  • M. Zhang, H.X. Deng, D. Gu, Q. Gu
    SINAP, Shanghai, People's Republic of China
  Dalian Coherent Light (DCL) Source is a FEL user facility in which HGHG scheme is adopted. Beam quality requirements for the linear accelerator (linac) are critical, including not only the beam brightness, but also the stability and the reliability. In this paper, optimization study is performed for the linac. Based on beam stability simulation in the longitudinal direction, the tolerant budget is formed for the short period jitter. For the transverse orbit error, beam based alignment (BBA) technique is implemented by beam dynamics simulations and the transverse jitter is also presented accordingly. Measurement method for the beam quality is also described in the paper.  
WEODB102 Generating Polarization Controllable FELs at Dalian Coherent Light Source 2071
  • T. Zhang, H.X. Deng, D. Wang, Z.T. Zhao
    SINAP, Shanghai, People's Republic of China
  • D.X. Dai, G.R. Wu, X.M. Yang, W.Q. Zhang
    DICP, Dalian, People's Republic of China
  Funding: 973 Program of China (2011CB808300), NSFC 11175240 and 11205234.
The property of the FEL polarization is of great importance to the user community. FEL pulses with ultra-high intensity and flexible polarization control ability will absolutely open up new scientific realms. In this paper, several polarization control approaches are presented to investigate the great potential on Dalian coherent light source, which is a government-approved novel FEL user facility with the capability of wavelength continuously tunable in the EUV regime of 50-150 nm. The numerical simulations show that both circularly polarized FELs with highly modulating frequency and 100 microjoule level pulse energy could be generated at Dalian coherent light source*.
*T. Zhang, et al., FEL Polarization Control Studies on Dalian Coherent Light Source, Chinese Physics C, 2013, to be published.
slides icon Slides WEODB102 [6.131 MB]