1. A machine which accelerates electrons in a circular path by keeping the frequency of the accelerating stream at a constant level while increasing the strength of the magnetic field guiding the stream.
2. A circular electron accelerator in which the frequency of the accelerating system is constant, the strength of the magnetic guide field increases, and the electrons move in orbits of nearly constant radius.
3. A synchrotron (an apparatus used in nuclear physics to produce beams of energetic charged particles and to direct them against various targets) designed to accelerate electrons.

The electron beam is allowed to strike an internal target, producing high-energy gamma rays which are used outside the machine.