  The special form of an electric discharge - "burn-through" in regard to the
ball lightning problem has been considered. Having been carried out within
closed volume, this mode of erosive discharge has shown the series of clear
differences consisting in the high gas density, formation of the metal-polymer
aerogel, the percolating current and unusual features of plasma's exhaust. The
conditions for its stable origination and the main stages of the discharge
process have been ascertained.
