Slide 41 of 59
Notes:
Coherent emission can be provided by particles grouping in bunches or clusters and radiating via an antenna mechanism. The phases of the radiation fields of the particles are not random, so the fields are summed. However, it is difficult, physically, to maintain these bunches for a fraction of a second or more.
Alternatively, coherent synchrotron emission waves radiated by relativistic electrons are amplified within the system.