Fig. 2.
From: Ballooning modes and their stability in a near-Earth plasma
The dispersion curves 
(solid lines) and 
(dashed lines) in the plane of squared parameters Ω2 = [ω/(κ
c
Va sinα)]2, (kǁ/κ
c
sinα)2 depending on parameter Λ = κ
P
/κ
c
(shown near curves) for Λ < 2γ. Other parameters are γ = 5/3, β = 1. The area 
corresponds to the non-propagation (opaque) region for the fast (Alfven-type) branch.