The axisymmetric pulsar magnetosphere.

A tentative model is discussed for the steady spin-down of an aligned rapidly rotating magnetic neutron star within the framework of classical physics. The electron currents which exert the braking torque on the star flow from the polar caps out to and beyond the light-cylinder, picking up energy from the electric force and angular momentum from the magnetic torque. At high enough energies the electrons emit incoherent gamma radiation; the associated loss of angular momentum enables the currents to cross magnetic field lines and so ultimately to return to the star at lower latitudes. Several examples are constructed that illustrate the required flow, but no claim is made that an acceptable approximation to a fully self-consistent model has yet been achieved. Reasons are given why such a classical model may spontaneously convert itself through pair production into a quantum model, in which circulation of primary electrons would still play an essential part.