[en] Production of a hot dense plasma by plasma flows escaping from a cylindrical surface in vacuum (inverted cylindrical corona) and colliding on the symmetry axis is studied analytically. It is shown that a plasma filament with a temperature substantially exceeding the temperature of the ambient medium is formed on the axis. This effect can manifest itself in axial discharges used to generate hard X radiation. Attention is drawn to the possibility of using this effect to heat the plasma to thermonuclear temperatures in inertial confinement fusion systems