AbstractIn this study, we present the results of an inversion of ionospheric phase scintillation data to characterize the plasma density irregularity parameters for the structures associated with a series of Polar Cap Patches. The parameter estimates obtained during the inversion suggests that the irregularities associated with Polar Cap Patches are predominantly composed of moderately elongated electron density rods aligned with the earth's magnetic field which in some instances are interbedded within sheet and wing like density structures. Analysis of the spatial and temporal distribution of the axial ratio (AXRs), which are the ratios of irregularity elongation parallel and perpendicular to the field, indicates that the measured phase scintillation indices increase roughly proportionally with AXR values for the rods but remain roughly constant for wings and sheets. These findings indicate that while wings and sheets can produce phase fluctuations, it is the apparent existence of rods that mark the occurrence of plasma processes that lead to the formation of field‐aligned irregularities that produce phase scintillations which are most significant.