Polar-cap accelerator and radio emission from pulsars

Electric currents j flow along the open magnetic field lines from the polar caps of neutron stars. Activity of a polar cap depends on the ratio alpha = j/c rho(GJ,) where rho(GJ) is the corotation charge density. The customary assumption arbitrary alpha. We argue that no significant activity is generated on field lines with 0 < alpha < 1 Charges are extracted is generated, leading to unsteady discharge on a scale height smaller than the size of the polar cap. The e(+/-) discharge can power observed pulsars. Voltage fluctuations in the discharge imply unsteady twisting of the open flux tube and generation of Alfven waves. These waves are ducted along the tube and converted to electromagnetic waves, providing a new mechanism for pulsar radiation.