  Young planets with masses approaching Jupiter's have tides strong enough to
clear gaps around their orbits in the protostellar disk. Gas flow through the
gaps regulates the planets' further growth and governs the disks' evolution.
Magnetic forces may drive that flow if the gas is sufficiently ionized to
couple to the fields. We compute the ionizing effects of the X-rays from the
central young star, using Monte Carlo radiative transfer calculations to find
the spectrum of Compton-scattered photons reaching the planet's vicinity. The
scattered X-rays ionize the gas at rates similar to or greater than the
interstellar cosmic ray rate near planets the mass of Saturn and of Jupiter,
located at 5 au and at 10 au, in disks with the interstellar mass fraction of
sub-micron dust and with the dust depleted a factor 100. Solving a gas-grain
recombination reaction network yields charged particle populations whose
ability to carry currents is sufficient to partly couple the magnetic fields to
the gas around the planet. Most cases can undergo Hall shear instability, and
some can launch magnetocentrifugal winds. However the material on the planet's
orbit has diffusivities so large in all the cases we examine, that
magneto-rotational turbulence is prevented and the non-ideal terms govern the
magnetic field's evolution. Thus the flow of gas in the gaps opened by the
young giant planets depends crucially on the finite conductivity.
