2022MNRAS.510L..34J

Recent multifrequency measurements of pulse widths W₅₀ for the long-period pulsar J0250+5854 by Agar et al. provide a unique insight into the emission process owing to its small polar-cap radius. The frequency dependence of W₅₀ can be simply understood as a consequence of the emitting plasma remaining under acceleration during the interval of radio emission. This is possible in a plasma of ions and protons but not in one of high-multiplicity electron-positron pairs. Extension of the model to the pulse profiles of the general pulsar population is considered briefly.