  Atmospheric mass-loss from Hot-jupiters can be large due to the close
proximity of these planets to their host star and the strong radiation the
planetary atmosphere receives. On Earth, a major contribution to the
acceleration of atmospheric ions comes from the vertical separation of ions and
electrons, and the generation of the ambipolar electric field. This process,
known as the "polar wind", is responsible for the transport of ionospheric
constituents to the Earth's magnetosphere, where they are well observed. The
polar wind can also be enhanced by a relatively small fraction of super-thermal
electrons (photoelectrons) generated by photoionization. We formulate a
simplified calculation of the effect of the ambipolar electric field and the
photoelectrons on the ion scale-height in a generalized manner. We find that
the ion scale-height can be increased by a factor of 2-15 due to the polar wind
effects. We also estimate a lower limit of an order of magnitude increase of
the ion density and the atmospheric mass-loss rate when polar wind effects are
included.
