Stark broadening of the Hα and Hβ lines by quasistatic and rapidly oscillating electric fields

Hα and Hβ hydrogen spectral line profiles are calculated for the case when radiating atoms are perturbed by an electric microfield E(t) = ''*''+E0 cos(Ω+φ) at GE0 << Ω. The profiles are generally close to those broadened by the quasistatic field alone. However, if the typical strength of the low-frequency field is ''*''0∼Ω/G, the Doppler width ''< ''approx0.1Ω and GE00.05 Ω, then the profiles show distinct narrow (of width ∼ GE0) spectral features. These features are created by the resonant values of ''*'', at which the separation between Stark sublevels of the upper or lower level, introduced by the field ''*'', is equal to the frequency Ω. Most pronounced features are situated from the line centre by ±pΩ, where p=1/3, 2/3, 1, 4/3 for the Hα line, and p=1/2, 1, 3/2, 2, 5/2 for Hβ. The features have different shapes (peaks, wells and their combinations) and may be used for the diagnostics of Langmuir turbulence or laser radiation in a plasma. (author)