  The electrostatic instabilities driven by the gradients of the density,
temperature and magnetic field, are discussed in their application to solar
magnetic structures. Strongly growing modes are found for some typical plasma
parameters. These instabilities i) imply the presence of electric fields that
can accelerate the plasma particles in both perpendicular and parallel
directions with respect to the magnetic field vector, and ii) can
stochastically heat ions. The perpendicular acceleration is to the leading
order determined by the $\bmath{E}\times \bmath{B}$-drift acting equally on
both ions and electrons, while the parallel acceleration is most effective on
electrons. The experimentally confirmed stochastic heating is shown to act
mainly in the direction perpendicular to the magnetic field vector and acts
stronger on heavier ions. The energy release rate and heating may exceed for
several orders of magnitude the value accepted as necessary for a
self-sustained heating in the solar corona. The energy source for both the
acceleration and the heating is stored in the mentioned background gradients.
