• H. Yamada
  SLLS, Shiga

Funding: MEXT 21st Century COE

We report the first lasing of the photon storage ring (PhSR) at Ritsumeikan Univ. This novel laser is a kind of FEL but is free from an undulator, and adopting a barrel shaped optical cavity placed inside the vacuum chamber around the 0.156 m radius exact circular electron orbit of synchrotron [1]. In the recent theoretical calculation [2], nearly 100 times larger gain is predicted in comparison with the earlier calculated [3]. We have observed the lasing with th·10²⁰ MeV synchrotron. We have measured the laser wavelength by FTIR with Si bolometer. Characteristic peaks at 30, 100, and 160 mm appear when fine-tuning of the magnetic field of synchrotron is applied. The wavelength shift appears as the time progress after injection due to the shifted electron orbit. The electron orbit radius is determined by the electron energy and the main magnetic field. All peaks grow in proportional to I² as the beam current I increase. The square growth indicates highly coherent nature of PhSR radiation.

[1] H. Yamada, Advances in Colloid and Interface Sci. 71-72 (1997) p. 371 [2] A.I. Kleev and H. Yamada, IEEE Journal of Quantum Electronics 39(6), 2003, p. 1 [3] K. Mima, K. Shimoda, and H. Yamada, IEEE J. Quantum Ele., vol. 27, p. 2572, 1991.

• H. Yamada
  SLLS, Shiga

Funding: JSP

The photon storage ring (PhSR) is based on an exact circular synchrotron. Yamada and his colleague have successfully produced two synchrotrons [1,2]. Both have 0.156 m small electron orbit radius. One is the 20 MeV version for PhSR, and the other is the 6 MeV version for brilliant hard X-ray production. The brilliance of this machine is comparable to the large conventional SR source. These tabletop synchrotrons are realized by the special beam injection scheme using resonance in betatron motion. This scheme provides nearly 100% beam injection efficiency leading to 3 A accumulated beam current as 100 mA peak current is injected from 6 or 20 MeV microtron. The beam lifetime is an order of 10 ms, and we perform the injection at 400 Hz. Interesting feature is the 10μsecond order fast radiation damping that appears due to the residual gas [3]. We think that the radiation from electrons caused by the residual gas enhances the stochastic radiation damping. This technology is useful for the low energy synchrotron.

[1] Hironari Yamada, Nucl.Instrum.Methods in Phys. Res. B199、2003, p.509 [2] D. Hasegawa et al., AIP Conference Proc. 716 ed. by Hironari Yamada, (2004) p.166 [3] Hironari Yamada, Advances in Colloid and Interface Sci. 71-72 (1997) p. 371