Stark shift by inhomogeneous strong E field

Stark broadening theory associates high values of E field to each point from the wings of an X-ray Lyman profile. For high densities (10²¹ – 10²⁵ cm^-3) plasmas the hypothesis that the ionic field is uniform — at least at atomic range — is no longer valid. Taylor's expansion of the quasi static perturbation shows that the real splitting is no longer symmetrical but the line profile can be interpreted as the addition of a macroscopic shift to the usual broadening.