Development of Next Generation Synchrotron Light Source -from Spontaneous to Stimulated Emission-
The latest synchrotron radiation facilities, the third generation light sources such as SPring-8, enter in a matured phase. The brightness of the synchrotron radiation has been increased by undulators and low emittance storage rings. The development of ERL (Energy Recovery LINAC) follows the way of further decreasing the electron beam emittance and generates much shorter radiation pulses. The other direction is moving from spontaneous radiation to stimulated emission, that is an FEL (Free Electron Laser). Different from conventional lasers, there is no constraint of light wavelengths in the FEL due to atomic or molecular energy levels. Therefore the FEL is a prospective candidate for an X-ray coherent light source. Currently two X-ray FELs are under construction in Japan and U.S., and X-ray coherent light will be available within two or three years. In this report, principles of synchrotron radiation and FEL are briefly summarized including the topics of next generation FEL sources.