In light sources, we make use of the fact that when charged particles are accelerated, they emit light (radiate). If electrons are accelerated back and forth in an antenna at kilohertz or Megahertz frequencies they radiate in the radio or TV portions of the electromagnetic spectrum. If electrons are constrained to move in a curved path (circles, spirals, and undulations are examples) they will be accelerating toward the inside of the curve and will also radiate what we call synchrotron light (or synchrotron radiation).
Synchrotron light of this type occurs naturally in the distant reaches of outer space. For example, magnetic fields are found throughout the Milky Way, such as the striking galactic center radio arc, comprising filamentary structures whose radio-wave emission spectra suggest the filaments are produced by synchrotron radiation from relativistic electrons spiraling around a magnetic field.
Accelerator-based synchrotron light was seen for the first time at the General Electric Research Laboratory in the USA in 1947 in a type of accelerator known as a synchrotron. First considered a nuisance because it caused the particles to lose energy, it recognized in the 1960s as light with exceptional properties. The light produced at today