  Despite the substantial progress made recently in understanding the role of
AGN feedback and associated non-thermal effects, the precise mechanism that
prevents the core of some clusters of galaxies from collapsing catastrophically
by radiative cooling remains unidentified. In this paper we demonstrate that
the evolution of a cluster's cooling core, in terms of its density,
temperature, and magnetic field strength, inevitably enables the plasma
electrons there to quickly become Cerenkov loss dominated, with emission at the
radio frequency of $\lesssim$ 350 Hz, and with a rate considerably exceeding
free-free continuum and line emission. However, the same does not apply to the
plasmas at the cluster's outskirts, which lacks such radiation. Owing to its
low frequency, the radiation cannot escape, but because over the relevant scale
size of a Cerenkov wavelength the energy of an electron in the gas cannot
follow the Boltzmann distribution to the requisite precision to ensure
reabsorption always occurs slower than stimulated emission, the emitting gas
cools before it reheats. This leaves behind the radiation itself, trapped by
the overlying reflective plasma, yet providing enough pressure to maintain
quasi-hydrostatic equilibrium. The mass condensation then happens by
Rayleigh-Taylor instability, at a rate determined by the outermost radius where
Cerenkov radiation can occur. In this way, it is possible to estimate the rate
at $\ap 2 M_\odot$~year$^{-1}$, consistent with observational inference. Thus
the process appears to provide a natural solution to the long standing problem
of `cooling flow' in clusters; at least it offers another line of defense
against cooling and collapse, should gas heating by AGN feedback be inadequate
in some clusters
