Inner vacuum gap formation and drifting subpulses in pulsars

The problem of formation of the inner vacuum gap in neutron stars with Ω · B < 0 is considered. It is argued by means of the condition Ti/Ts > 1, where Ti is the melting temperature of surface 56 26Fe ions and Ts is the actual temperature of the polar cap surface, that the inner vacuum gap can form, provided that the actual surface magnetic field is extremaly strong (Bs> ∼ 10 13 G) and curved (R < 10 cm), irrespective of the value of dipolar component measured from the pulsar spin down rate. The calculations are carried out for pulsars with drifting subpulses and/or periodic intensity modulations, in which the existence of the quasi steady vacuum gap discharging via E×B drifting sparks is almost unavoidable.