The Shape of Wings of Hydrogenic Spectral Lines Under Linearly Polarized Monochromatic Waves in Plasmas

There is a garden variety of waves in plasmas. Some of these waves can be monochromatic (or quasimonochromatic) and linearly polarized. Examples are Langmuir waves, lower hybrid waves (in magnetized plasmas), and the electromagnetic radiation penetrating into plasma from the outside (such as the laser radiation). In the present article, we focus at the practically important situation of the strong modulation of the atomic oscillator by such waves. For hydrogenic spectral lines, this leads to numerous satellites, such that in practice only the envelope of the satellites is observed. We study the shape of the wings of hydrogenic spectral lines in this situation. We show that in this situation, the logarithm of the observed intensity versus the detuning ∆λ from the unperturbed wavelength of the spectral line should exhibit a quasilinear dependence. In the case where there is no laser radiation in a plasma, finding such a quasilinear dependence for the observed low-excited (i.e., the most intense) hydrogenic spectral lines would be the indication of the development of the lower hybrid oscillations in the plasma. This is the first spectroscopic method for detecting the lower hybrid oscillations in plasmas, to the best of our knowledge. Furthermore, we show that the experimental value of the frequency of the lower hybrid oscillations can be estimated from the tangent of such quasilinear dependence. Then, one can estimate either the electron density, if the magnetic field is known, or the magnetic field, if the electron density is known.