The development of in-vacuum undulators, in which a short period is achieved by placing periodic magnet inside the accelerator’s vacuum pipe, began at KEK around 1988, and light was successfully generated for the first time in December 1990.
This technology can transform synchrotron radiation facilities into compact and energy-saving ones, because short-period undulators can generate high energy and intense X-rays even in 3-GeV class storage ring. The development has led to a trend towards the construction of synchrotron radiation facilities installed in-vacuum undulators around the world.
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Image: The first in-vacuum undulator (period length : 4cm)
Credit: Photon Factory, KEK