On the double-plane plasma lensing

Plasma lensing is the refraction of low-frequency electromagnetic rays due to cold free electrons in universe. For sources at a cosmological distance, there observational evidence elongated, complex plasma structures along line sight requiring multi-lens-plane description. To investigate limits single-plane lensing, we set up double-plane lens with projected Gaussian electron density each plane. We compare scenarios corresponding effective configurations. Our results show how lenses can be distinguished from by observables, i.e. resolved multiple image positions, relative magnifications, time delays, and pulse shapes. fast radio bursts, observed shape may dominated effect, allowing us neglect intrinsic source distinguish different The time-domain observables turn out most salient features tell multi- apart.