Author: Huang, S.
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MOP076 Free-Electron Laser Driven by a 500 MeV Laser Plasma Accelerator Beam 217
 
  • W. Qin, J.E. Chen, S. Huang, K.X. Liu, X.Q. Yan, L. Zeng
    PKU, Beijing, People's Republic of China
  • Y. Ding, Z. Huang
    SLAC, Menlo Park, California, USA
 
  A laser plasma accelerator is under construction at Peking University and several hundred MeV electron beams are expected. In this paper we discuss applying a 500 MeV beam with 1% relative energy spread to FEL. Bunch decompression method is considered to deal with the large energy spread of the beam. Emittance growth induced by large divergence and energy spread in electron beam transport has been treated with the chromatic matching manipulation. Simulation shows that 100 MW level, 6.3 fs , 0.008 bandwidth output can be obtained for 30 nm FEL. TGU method with assumed matched beam is also discussed as a comparison.  
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TUB03
Generating Femtosecond to Sub-Femtosecond X-Rays with a Modulated Chirped Beam in a Self-Seeded FEL  
 
  • S. Huang
    PKU, Beijing, People's Republic of China
  • Y. Ding, Z. Huang, G. Marcus
    SLAC, Menlo Park, California, USA
 
  We propose a scheme to generate ultrashort soft X-ray pulses in a self-seeded FEL. In this scheme, a time-energy chirped electron beam is first modulated by an infrared laser with the wavelength of a few microns. It is then used to drive the self-seeded FEL. During the selfseeding section, besides the regular functions of the self-seeding chicane and the grating monochromator, the chicane is also used to shear the previously modulated electron beam, leading to current spikes in the temporal profile. Since the seeded pulse length from the chirped beam is much shorter than the electron bunch, we can choose to align the seed with one of the current spikes for generating a single short pulse. Simulations indicate that soft X-ray pulses with a fwhm of less than 1 fs and peak power at 10 GW level can be obtained.  
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TUB05 Tunable High-power Terahertz Free-Electron Laser Amplifier 305
 
  • G. Zhao, S. Huang, K.X. Liu, W. Qin, L. Zeng
    PKU, Beijing, People's Republic of China
  • C.H. Chen, Y.C. Chiu, Y.-C. Huang
    NTHU, Hsinchu, Taiwan
 
  In the THz spectrum, radiation sources are relatively scarce. Although recent advancement on optical technologies has enabled THz radiation generation covering a broad spectral range, free-electron laser (FEL) continues to be the most importance source for generating high-power THz radiation. Here we present an ongoing collaboration between Peking University (PKU) and National Tsinghua University (NTHU) to demonstrate high peak and average powers from a THz free-electron laser amplifier driven by a superconducting accelerator system at PKU. The superconducting accelerator comprises the DC-SRF photoinjector and a linac utilizing two 1.3 GHz Tesla-type cavities. It is expected to deliver high repetition rate electron beam with the energy of 10-25 MeV and rms bunch length of about 3 ps. The driver laser of the photoinjector is a mode-locked frequency-quadrupled Nd:YVO4 laser at 266 nm. We use the remaining gun driver laser power at 1064 nm to pump a THz parametric amplifier (TPA) which designed at NTHU and generate the THz seed radiation for the FEL amplifier. The signal laser of the TPA is tunable over 2 THz, permitting generation of radiation between 0.5 and 2.5 THz to seed the FEL amplifier. With our design parameters and computer simulation in GENESIS, we expect to generate narrow-band, wavelength-tunable THz radiation with sub-MW peak power and Watt-level average power.  
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TUP023 A Modified Self-Seeded X-ray FEL Scheme Towards Shorter Wavelengths 409
 
  • L. Zeng, J.E. Chen, S. Huang, K.X. Liu, W. Qin
    PKU, Beijing, People's Republic of China
  • Y. Ding, Z. Huang, G. Marcus
    SLAC, Menlo Park, California, USA
 
  We present a modified self-seeded FEL scheme for harmonic generation. Different from classical HGHG scheme whose seed laser is a conventional laser with longer wavelength, this scheme first uses a regular self-seeding monochromator to generate a seed laser, followed by a HGHG configuration to produce shorter-wavelength radiations. As an example, we perform start-to-end simulations to demonstrate the second and third harmonic FELs from a soft x-ray self-seeding case at the fundumental wavelength of 1.72 nm. The harmonic performance results will be discussed.  
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WEB01 A Two-Color Storage Ring FEL 571
 
  • J. Yan, H. Hao, S.F. Mikhailov, V. Popov, Y.K. Wu
    FEL/Duke University, Durham, North Carolina, USA
  • S. Huang
    PKU, Beijing, People's Republic of China
  • J.Y. Li
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  • N. Vinokurov
    BINP SB RAS, Novosibirsk, Russia
  • J. Wu
    SLAC, Menlo Park, California, USA
 
  Funding: This work is supported in part by the US DOE grant no. DE-FG02-97ER41033.
Using different undulator configurations on the Duke storage ring, we have successfully achieved lasing with a novel two-color storage ring FEL. Using a pair of dual-band FEL mirrors, simultaneous lasing was realized in IR (around 720 nm) and in UV (around 360 nm). With this two-color FEL, we have demonstrated independent wavelength tuning of either IR or UV lasing. With careful tuning, we have also realized harmonic lasing with the UV lasing tuned to the second harmonic of the IR lasing. The tuning of harmonic two-color lasing has also been demonstrated with the locked wavelengths. Furthermore, we have demonstrated good control of the FEL power sharing between the two colors. The two-color FEL has created new opportunities to drive a two-color Compton gamma-ray beam at the High Intensity gamma-ray Source at Duke.
 
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