LNS, Sendai
JASRI/SPring-8, Hyogo-ken
A project of coherent synchrotron radiation source at Terahertz (THz) wavelength region has been developed at Tohoku University, Sendai [1]. The project may involve novel high brightness electron guns employing cathodes of single crystal LaB6 for production of a very short bunch length less than 100 fs [2]. The source has been designed based on isochronous ring optics to preserve the short bunch length, but the ring is not a storage ring. The optics of the racetrack type isochronous ring has resulted from consideration of path length differences due to both the betatron motion and the energy deviation. The coherent THz photons are emitted from circulating electron bunches injected from the linac. Even the beam turns by dipole magnets, the bunch shape does not collapse because of nearly complete isochronous optics of the ring. Since production of the coherent THz radiation requires the bunch length less than 100 fs (stdv, if Gaussian), the maximum path length difference created by passing through the dipoles is controlled to not exceed a couple of tens fs. Predicted spectrum of the Coherent Thz radiation and its characteristics will be also presented.
[1] H. Hama, Proc. the 27th Int. FEL Conf., Stanford, CA, (2005) pp1-6.
[2]T. Tanaka, F. Hinode, M. Kawai, H. Hama, Proc. the 27th Int. FEL Conf., Stanford, CA, (2005) pp142–145
