The invention relates to a gas generator comprising: a primary chamber (3) for storing and burning a primary pyrotechnic compound, having a nozzle (17) for expelling the products of combustion of the primary compound in the form of a primary jet in an axial direction of the generator; an ignition system (11); a secondary chamber (5) for storing and breaking down a secondary compound, the primary jet driving the breakdown of the secondary compound, the secondary chamber having an inlet opening (14) for the primary jet; at least one stabilization zone communicating with the secondary chamber and with the outside of the generator. In a first version, the stabilization chamber (12) extends at least partially around the primary chamber. In a second version, the stabilization zone extends downstream of the secondary chamber and a shield is formed facing the primary jet at the wall dividing the secondary chamber from the stabilization zone.