The mechanism of coherent radio emission in some classes of pulsar
  Radio luminosities have been estimated from published data for a well-defined homogeneous set of 29 normal pulsars. The radio-frequency energies per unit charge in the primary accelerated particle beam are given for each pulsar and form a distribution more than two orders of magnitude in width. The values found show that pulsars are extremely efficient generators of radiation below 1 - 10 GHz given the kinematic constraints which are obtained here in the cases of electron-positron and ion-proton plasmas. Our conclusion is that only the ion-proton plasma source is consistent with the spectra of normal and millisecond pulsars and we list and describe the factors which together support this conclusion. 
P. B. Jones
astro-ph.HE