We examined a model of partially screened gap region above the polar cap, in
which the electron-positron plasma generated by sparking discharges coexists
with thermionic flow ejected by the bombardment of the surface beneath these
sparks. Our special interest was the polar cap heating rate and the subpulse
drifting rate, both phenomena presumably associated with sparks operating at
the polar cap. We investigated correlation between the intrinsic drift rate and
polar cap heating rate and found that they are coupled to each other in such a
way that the thermal X-ray luminosity Lx from heated polar cap depends only
on the observational tertiary subpulse drift periodicity P^3 (polar cap
carousel time). Within our model of partially screened gap we derived the
simple formula relating Lx and P^3, and showed that it holds for
PSRs B0943+10 and B1133+16, which are the only two pulsars in which both
Lx and P^3 are presently known.Comment: 4 page