Page "Synchrotron light source" Paragraph 13

Synchrotron radiation may occur in accelerators either as a nuisance, causing undesired energy loss in particle physics contexts, or as a deliberately produced radiation source for numerous laboratory applications.

Electrons are accelerated to high speeds in several stages to achieve a final energy that is typically in the gigaelectronvolt range.

The electrons are forced to travel in a closed path by strong magnetic fields.

This is similar to a radio antenna, but with the difference that the relativistic speed changes the observed frequency due to the Doppler effect by a factor.

Relativistic Lorentz contraction bumps the frequency by another factor of, thus multiplying the gigahertz frequency of the resonant cavity that accelerates the electrons into the X-ray range.

Another dramatic effect of relativity is that the radiation pattern is distorted from the isotropic dipole pattern expected from non-relativistic theory into an extremely forward-pointing cone of radiation.

This makes synchrotron radiation sources the brightest known sources of X-rays.

The planar acceleration geometry makes the radiation linearly polarized when observed in the orbital plane, and circularly polarized when observed at a small angle to that plane.