  Azimuthal structures in cylindrical Penning discharge are studied with 2D3V
radial-azimuthal PIC/MCC model with the axial magnetic field. The discharge is
self-consistently supported by ionization due to the axial injection of
electrons. It is shown that the steady-state discharge can be supported in two
different regimes with different type of observed azimuthal structures. The
transition between the regimes is controlled by the mechanism of the energy
input to the discharge. In the first regime (low energy of the injected
electrons), with the pronounced $m=1$ spoke activity, the power input is
dominated by the energy absorption due to the radial current and
self-consistent electric field. In the other regime (higher energy of the
injected electrons), with prevalent small scale $m>1$ spiral structures, and
the lower values of the anomalous transport, the total energy deposited to the
discharge is lower and is mostly due to the direct input of the kinetic energy
from the axial electron beam. We show that the large (m=1) spoke and small
scale structures occur as a result of Simon-Hoh and lower hybrid instabilities
driven by the electric field, density gradient, and collisions. We show that
the spoke frequency follows the equilibrium ion rotation frequency.
