Spontaneously Emitted Fluctuations in Unmagnetized Plasmas
Every stable plasma spontaneously emits electromagnetic fluctuations due to the random motions of the charged plasma particles. Consequently, the plasma variables such as density, pressure, and electromagnetic fields fluctuate in position and time. We will derive the general expressions for the electromagnetic fluctuation spectra in unmagnetized plasmas using fully relativistic dispersion functions and form factors for the important class of isotropic plasma particle distribution functions. The special case of aperiodic fluctuations will be analyzed for an electron-proton plasma with a Maxwellian and a Lorentzian distribution function.
The fluctuation intensities are dominated by the contribution from a new collective, damped mode. We will determine the magnetic field strengths from this mechanism.