An injection system for a turbine engine combustion chamber is provided. The injection system includes a first annular deflector surrounded by the bowl of the injection system and extending in the downstream direction from the downstream transverse surface that delimits the downstream side of the swirler. The first deflector has a free downstream end offset in the upstream direction from a downstream end of the bowl, so as to guide an air film output from the first orifices formed through the bowl. The internal radius of the cross section of the first annular deflector increases from the downstream transverse surface as far as the downstream end of the first annular deflector.