On the Propagation of a Circularly Polarized Electromagnetic Wave Through a Temporal Interface Between Air and a Magneto Plasma

It is shown that a right-hand/left-hand circularly polarized wave propagating along the magnetic field is converted to three waves by a suddenly created plasma. The right-hand circularly polarized wave is converted to two forward (R-mode and slow R-mode of the magnetoplasma) and one backward (L-mode) propagating waves; and in the left-hand circular polarization case, the wave is converted to one forward (L-mode) and two backward (R-mode and slow R-mode) propagating waves. As the background magnetic field approaches zero, the slow R-mode converts to a wiggler magnetic field, which is found in the unmagnetized case. Conservation of wave energy and power flux in the mode conversion is verified. Using the Abraham expression as the relationship between the momentum and energy of a photon in a dielectric medium, conservation of momentum in the mode conversion is also demonstrated. When a strong magnetic field is embedded in the background, a suddenly created low-density plasma can achieve a large frequency upshift on a right-hand circularly polarized wave.