Author: D.E. Ruiz

Abstract:  Even diffraction aside, the well-known equations  of geometrical optics (GO) are not entirely ac­curate.   Traditional  GO treats  wave rays as classical particles,  which are completely described  by their coordinates and momenta,  but rays have another degree of freedom, namely, polarization.  The polarization degree of freedom manifests itself as an effective (classical) spin that  can be assigned to rays and can affect the wave dynamics accordingly.  A well-known example of associated  effects is wave-mode conversion, which can be interpreted as spin precession. However, there are also other, less-known manifestations  of the wave spin, such as polarization-driven  bending of ray trajectories. This  work presents  an extension  and  reformulation  of GO as a first-principle  Lagrangian  theory, whose effective-gauge Hamiltonian  governs all the aforementioned  polarization  phenomena simul­taneously.  As an example,  the theory  is applied  to describe the  polarization-driven  divergence of right-hand  and left-hand circularly polarized electromagnetic  waves in weakly magnetized plasma.

Submitted to: Physics of Plasmas
_________________________________________________________________________________________________

Download PPPL-5330 836 KB (pdf  10 pp)
_________________________________________________________________________________________________