Using plasma experiments to illustrate a complex index of refraction

The index of refraction for the propagation of a wave in a plasma depends on the plasma density, background magnetic field, and frequency of the wave. The study of plasma wave propagation is an excellent tool for teaching students the subtleties involved in a complex media rather than in glass or water where the index of refraction is close to a constant. Whistler waves were launched and detected in a plasma physics laboratory at UCLA devoted to involving high school students and teachers. The magnetic field of the wave was measured in space and time and the wavenumbers at a variety of frequencies were determined. The index of refraction predicted by Appleton’s equation was used to reconstruct the two-dimensional phase fronts and compared to the laboratory data with excellent agreement. The experimental techniques are discussed in conjunction with their use as an educational tool. VC 2011 American Association of Physics Teachers. [DOI: 10.1119/1.3591341]