Insertion device

In physics, an insertion device is a group of magnets that can be placed on a straight segment of a particle accelerator to be a synchrotron light source. They are called an "insertion devices" because they replace pipe that otherwise would hold the vacuum needed to maintain the particle beam path. Many times, insertion devices are used on the circular path of a synchrotron or a storage ring.
There are two types of insertion devices. Undulators make electromagnetic radiation that is tuned to a narrow frequency range. Wigglers make a wide range of electromagnetic radiation frequencies.