High-pressure gas turbine for a turbomachine extending around a longitudinal axis, the turbine comprising: - a nozzle guide vane assembly comprising an internal annular platform and an annular array of fixed vanes, each fixed vane being connected, radially inwards, to the internal annular platform, - an annular array of movable blades mounted downstream of the nozzle guide vane assembly, comprising a disc from which blades extend radially outwards, - an upstream sealing element applied against a downstream face of the nozzle guide vane assembly, and a downstream sealing element applied against an upstream face of the disc of the annular array of movable blades, - the upstream sealing element comprising an annular portion from which a downstream annular deflector extends longitudinally downstream, said annular portion having a radially outer portion comprising a upstream annular cavity, said upstream cavity being open at a radially outer annular clearance delimited between the downstream face of the nozzle guide vane assembly and the upstream sealing element, - the downstream sealing element comprising a first upstream deflector arranged, at least in part, radially internally to the internal annular platform of the nozzle guide vane assembly and radially externally to the downstream deflector of the upstream sealing element, said downstream sealing element further comprising a second upstream deflector arranged, at least in part, radially internally to the downstream deflector, the downstream deflector extending, at least in part, radially facing the first and second upstream deflectors (47, 48), the first and second upstream deflectors (47, 48) and the downstream deflector defining a double baffle. - a nozzle guide vane assembly comprising an internal annular platform and an annular array of fixed vanes, each fixed vane being connected, radially inwards, to the internal annular platform, - an annular array of movable blades mounted downstream of the nozzle guide vane assembly, comprising a disc from which blades extend radially outwards, - an upstream sealing element applied against a downstream face of the nozzle guide vane assembly, and a downstream sealing element applied against an upstream face of the disc of the annular array of movable blades, - the upstream sealing element comprising an annular portion from which a downstream annular deflector extends longitudinally downstream, said annular portion having a radially outer portion comprising a upstream annular cavity, said upstream cavity being open at a radially outer annular clearance delimited between the downstream face of the nozzle guide vane assembly and the upstream sealing element, - the downstream sealing element comprising a first upstream deflector arranged, at least in part, radially internally to the internal annular platform of the nozzle guide vane assembly and radially externally to the downstream deflector of the upstream sealing element, said downstream sealing element further comprising a second upstream deflector arranged, at least in part, radially internally to the downstream deflector, the downstream deflector extending, at least in part, radially facing the first and second upstream deflectors (47, 48), the first and second upstream deflectors (47, 48) and the downstream deflector defining a double baffle.