Abstract:
The properties of the electromagnetic radiation undergo a fundamental change in the presence of a medium in general and a plasma in particular. Specially the dispersion relation is modified in a way that in a plasma, the square of the four-momentum of a photon is not zero. In an unmagnetized plasma, it is equal to the square of the plasma frequency. Further, the electron-photon coupling vertex along with the energy momentum conservation laws are also modified if the Compton processes occur in a plasma. As a result the cross sections of the three Compton processes, viz., the Compton scattering, the electron-positron pair annihilation and production become functions of the plasma density. The cross sections are found to change significantly in highly dense plasmas.
