Polar cap relief and integrated pulse structure

An explanation is offered for the complexity and stability of integrated pulse profiles. The authors propose that the pulse structure arises from surface irregularities at the polar caps, and indicate how the surface relief affects the number of charges which are released into the magnetosphere and create the observed radio radiation. The electrons produced in the vacuum break-down in the polar gap carry enough energy to continually modify the surface relief of the polar caps, and one way in which the surface could be modified in a timescale of a million years is suggested. (Auth.)