Author: Jia, Q.K.
Paper Title Page
TUP008 An Analysis of Optimum Out-coupling Fraction for Maximum Output Power in Oscillator FEL 368
  • Q.K. Jia
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  The effect of the out-coupling fraction on the output power in oscillator FEL is analyzed. The formulas of the optimum out-coupling fraction and the corresponding maximum output power are given. They are dependent on the initial small signal gain and the passive loss rate of the light in the optical cavity. The initial comparison show that the result given by the formula agree well with the results in references.  
TUP009 A Simple Method for Generating a Few Femtosecond Pulses in Seeded FELs 371
  • H.T. Li, Z.G. He, Q.K. Jia
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  Funding: Work supported by Major State Basic Research Development Program of China (2011CB808301) and the Fundamental Research Funds for the Central Universities of China (WK2310000045)
We propose a simple method to generate a few femtosecond pulses in seeded FELs. We use a longitudinal energy-chirped electron beam passing through a dogleg where transverse dispersion will generate a horizontal energy chirp, then in the modulator, a seed laser with narrow beam radius will only modulate the centre part of electron beam and short pulses in high harmonics will be generated in the radiator. Using a representative realistic set of parameters, we show that 30 nm XUV pulse with duration of 8 femtoseconds (FWHM) and peak power of GW level can be generated from a 180 nm UV seed laser with beam waist of 75 m.
TUP057 Development of Compact THz-FEL System at Kyoto University 501
  • S. Suphakul, T. Kii, H. Ohgaki, Y. Tsugamura, H. Zen
    Kyoto University, Kyoto, Japan
  • Q.K. Jia
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  We are developing a compact accelerator based terahertz (THz) radiation source by free-electron laser (FEL) at the Institute of Advanced Energy, Kyoto University. The system consists of a 1.6 cell BNL type photocathode RF-gun, a focusing solenoid magnet, a magnetic bunch compressor, focusing quadrupoles and an undulator. The system generates an ultra-short electron pulse in a few hundred femtoseconds shorter than radiation wavelength, resulting in super-radiant emission from the undulator. The target radiation wavelength is 100 to 300 μm. A tracking simulation and optimization are performed by using PARMELA and General Particle Tracer (GPT) code. The FEL radiations are analyzed by a 1 dimensional FEL theory. The design parameters, simulation results and status are reported and discussed in this paper.