Radiation emitted by a charged particle under acceleration.
Radiation emitted by a charged particle moving in a magnetic field is called synchrotron radiation .
The energy spectrum of rays due to bremsstrahlung of electrons decelerated in the field of atomic nuclei depends on the energy levels of the atomic electrons, due to the screening effect they have on the moving particle, and on the particle velocity. The spectrum extends up to quanta of the energy of the moving particle. To a reasonable approximation, the amount of energy radiated per energy interval is constant. In the relativistic limit, the radiated energy is contained in a narrow cone of average half-angle independent of radiated energy. The term internal bremsstrahlung is used to describe the radiation of non-virtual quanta, i.e. photons or gluons, by particles participating in an interaction.