  The influence of surface small scale magnetic field on the heating of PSR
J0250+5854 polar cap is considered. It is assumed that polar cap is heated only
by reverse positrons, accelerated in pulsar diode. It is supposed that pulsar
diode is in stationary state with lower plate nearby the star surface (polar
cap model), occupies all pulsar tube crosssection and operates in regime of
steady space charge limited electron flow. The influence of small scale
magnetic field on electric field inside pulsar diode is taken into account. To
calculate the electron-positron pairs production rate we take into account only
the curvature radiation of primary electrons and its absorption in magnetic
field. It is assumed that part of electro-positron pairs may be created in
bound state (positronium). And later such positroniums are photoionized by
thermal photons from star surface.
