Author: Hama, H.
Paper Title Page
WEPC036 Coherent Synchrotron Radiation Source Based on an Isochronous Accumulator Ring with Femtosecond Electron Bunches 2085
 
  • N.Y. Huang
    NTHU, Hsinchu, Taiwan
  • H. Hama, F. Hinode, S. Kashiwagi, M. Kawai, X. Li, F. Miyahara, T. Muto, K. Nanbu, Y. Tanaka
    Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
  • W.K. Lau
    NSRRC, Hsinchu, Taiwan
 
  A compact isochronous accumulator ring has been studied as a source of coherent synchrotron radiation (CSR) at a wavelength region from THz to GHz. Since the thermionic rf gun is substantially stable in general, we anticipate a bunch train of very short electron pulses can be provided satisfactorily by means of velocity bunching. Careful numerical simulations show possibility of the bunch length of much less than 100 fs with a bunch charge of 20 pC, which will contain sufficiently large form factor for production of CSR at the wavelengths longer than ~ 0.1 mm. The coherent THz radiation of high average power will be achieved if the short bunches can be circulated in the accumulator ring without bunch lengthening. This paper will describe the optimization of thermionic injector to produce femtosecond bunches in addition to study of the lattice designing of complete isochronous optics for the accumulator ring.  
 
THPC040 Expected Performance Characteristic of Accelerator-based THz Source at Tohoku University 2990
 
  • H. Hama, F. Hinode, S. Kashiwagi, M. Kawai, X. Li, T. Muto, K. Nanbu, Y. Tanaka
    Tohoku University, School of Science, Sendai, Japan
  • N.Y. Huang
    NTHU, Hsinchu, Taiwan
 
  Funding: This work is supported by the Ministry of Education, Science, Sports and Culture, Grant-in-Aid for Scientific Research (S), Contract #20226003.
Sources of coherent synchrotron radiation at THz wavelength region have been constructed at Tohoku University. Bunch train of extremely shorter electron pulse less than 100 fs will be provided by an injector linac employing thermionic rf gun, where the bunch compression will be performed by means of velocity bunching in an accelerator structure. Radiation source under development are a Halbach type planar undulator and an accumulator isochronous ring. The undulator employs large gap and long period length configuration, so that the resonant frequency of 1 THz is achieved when a lower beam energy of ~ 20 MeV. Since spectrum of coherent synchrotron radiation (CSR) is strongly depending on longitudinal bunch form factor, we have calculated CSR spectra for various conditions of the beam to evaluate the performance of the THz source. Numerical simulation with multi-particle system has been carried out to understand the radiation power and angular distribution as well. The beam transport in the undulator is crucial for quality of the radiation because the beam energy is very much low relative to strong focusing power. Characteristics of THz CSR from the undulator will be discussed.
 
 
THPC041 Injector System of Test Accelerator as Coherent Terahertz Source 2993
 
  • S. Kashiwagi, H. Hama, F. Hinode, M. Kawai, X. Li, T. Muto, K. Nanbu, Y. Tanaka
    Tohoku University, School of Science, Sendai, Japan
  • N.Y. Huang
    NTHU, Hsinchu, Taiwan
  • F. Miyahara
    KEK, Ibaraki, Japan
 
  Funding: This work is supported by the Ministry of Education, Science, Sports and Culture, Grant-in-Aid for Scientific Research (S), Contract #20226003.
A test accelerator as a coherent terahertz source (t-ACTS) project has been under development at Tohoku University, in which a generation of intense coherent terahertz (THz) radiation from sub-picosecond electron bunch will be demonstrated. We will supply a wide-band coherent radiation from bending magnets in an isochronous ring and a narrow-band coherent THz radiation using an undulator in a linac. Stable generation of very short electron bunch is one of the key issues in the t-ACTS project. The injector system is consists of a thermionic RF gun with two independent cavity cells, an alpha magnet and an accelerating structure. A velocity bunching scheme is employed to produce the very short electron bunch. Components of the t-ACTS injector except the accelerating structure have already been installed and we have started a high power RF processing of the gun cavities. The characteristics of electron bunch extracted from the RF gun are measured by varying phase and amplitude of input RF fields for the gun cavities. The status of t-ACTS project will be presented in the conference.