National Synchrotron Light Source - Design

Design

Electrons are the generators of the synchrotron radiation that is used at the end stations of beamlines. The electrons are first produced by a 100KeV triode electron gun. These electrons then proceed through a linear accelerator (linac), which gets them up to 120MeV. Next, the electrons enter a booster ring, where their energy is increased to 750 MeV,, and are then injected into either the VUV ring or the X-ray ring. In the VUV ring, the electrons are further ramped up to 825MeV and electrons in the X-ray ring are ramped to 2,800 MeV.

Once in the ring, VUV or X-ray, the electrons orbit and lose energy as a result of changes in their angular momentum, which cause the expulsion of photons. These photons are deemed white light, i.e. polychromatic, and are the source of synchrotron radiation. Before being used in a beamline endstation, the light is collimated before reaching a monochromator or series of monochromators to get a single and fixed wavelength.

During normal operations, the electrons in the storage rings lose energy and as such, the rings must be re-injected every 12 (X-ray ring) and 4 (VUV ring) hours. The difference in time arises from the fact that VUV light has a larger wavelength and thus has lower energy which leads to faster decay, while the X-rays have a very small wavelength and are high energy.