  The Langmuir-Landau-Centrifugal Drive (LLCD), that can effectively "convert"
gravitational energy into particles, is explored as a driving mechanism
responsible for the extreme thermal luminosity acquired by some active galactic
nuclei (AGN). For this purpose we consider equations governing the process of
heating of AGN magnetospheres. In particular, we examine the Fourier components
of the momentum equation, the continuity equation and the Poisson equation in
the linear approximation and estimate the growth rate of the centrifugally
excited electrostatic waves and the increment of the Langmuir collapse. It is
shown that the process of energy pumping is composed of three stages: in the
first stage the energy is efficiently transferred from rotation to the
electrostatic modes. In due course of time, the second regime - the Langmuir
collapse - occurs, when energy pumping is even more efficient. This process is
terminated by the Landau damping, when enormous energy is released in the form
of heat. We show that the magnetospheres of the supermassive black holes with
luminosities of the order of $10^{45-46}$erg/s can be heated up to
$10^{6-10}$K.
