ABSTRACT
This chapter discusses the physics of the radiation mechanisms that produce continuous spectra. The emission of a continuous spectrum usually involves a large number of emitting particles with a range of energies. Thermal emission occurs as a consequence of the random electromagnetic interactions, or “collisions,” between charged particles with thermal motions. In the 19th century, the spectrum of a blackbody was measured; however the physics of the day was unable to describe why the emission had the distribution with wavelength that was observed. The total radiation emitted by a cooling body is not correctly described merely as the sum of all the individual emission processes since the particles within the body can also absorb radiation. The emission coefficient of bremsstrahlung radiation from a thermal distribution of electrons and ions is found to have a complicated dependence on temperature and density. The emission from non-relativistic free electrons in a magnetic field is called cyclotron radiation.
