We present the results of the theoretical studies
of the plasma heating in the flows which converge toward
the axis of cylindrical cavity. We show that as a result
of the shock wave reflection from the axis, the narrow
hot filament is formed. This phenomenon is important for
the interpretation of the dynamic processes in the electric
discharges used for X-ray generation. We notice that the
plasma parameters which can be of interest for inertial
confinement fusion (ICF) can be reached in such the processes.