Stochastic electron gas theory of coherence in laser-driven synchrotron radiation

The transition from coherent to incoherent. laser-driven synchrotron radiat ion is. studied within. the framework of a stochastic electron gas model. T he fundamental difference between this approach and a relativistic fluid mo del resides in the fact that, for any number of incoherently phased point e lectrons, the 4-current contains Fourier components at arbitrarily short wa velengths, whereas the fluid model introduces an unphysical cutoff scale.