Kawakatsu Yamada and, Norihiro Sei and Hiroshi Ogawa of the Quantum Radiation
Research Group, the Research Institute of Instrumentation Frontier of the National
Institute of Advanced Industrial
Science and Technology (AIST) have developed a compact free electron laser
(FEL) that can simultaneously emit high-intensity short pulse beams of monochromatic
infrared light and X-ray.
 | | Picture of the electron storage ring NIJI-IV for an FEL |
In this study, we used an electron storage ring NIJI-IV for the FEL that was
jointly developed by AIST and Kawasaki Heavy Industries, Ltd. We additionally
developed an optical klystron ETLOK-III, a light source of length 3.6 m with
a long undulator period and strong magnetic field, and a highly stable optical
resonator system with a vibration displacement of less than 0.5 µm. By
combining them, an infrared FEL is developed with a maximum output of 1.6 mW
and wavelength of 0.84–1.50 µm (infrared light region).
Quasi-monochromatic X-rays are successfully generated in the optical resonator
in which an infrared FEL beam collides with a bunch of electrons moving at a
speed close to the speed of light. The number of generated X-ray photons is
roughly 106 photons/s with the energy (equivalent to wavelength) of 1.2–2.1
MeV. It is to be noted that the realized energy range overlaps the range of
0.3–1.5 MeV where a monochromatic X-ray source has so far been believed
very difficult to realize.
A prospective application of the present system would be a high-flux two-color
light source of infrared light and an X-ray with variable energy (equivalent
to wavelength). If applied to the accelerator such as an energy-recovery linac,
one would be able to realize a quasi-monochromatic X-ray source with the energy
of over 0.3 MeV and the yield of 1012 photons/s, of the level not easily attainable
even in a large synchrotron radiation facility. This type of X-ray beam would
offer new measuring methods for magnetic material research, and would also contribute
to the development of an ultra-high density magnetic recording system.
Posted November 16th, 2009
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