Autonomous working gas supply system, use of such a system to pressurize a container, laucher stage including such a system

The working gas, stored at a cryogenic temperature in a tank (3), is heated in an exchanger (6) by hot gases (7) resulting from catalytic combustion, through a catalyst bed (8), of a metered mixture of fuel gas and oxidant gas stored in tanks (10, 11). Application in particular to the pressurization of cryogenic engine propellant tanks of launcher stages.