The invention relates to a device (100) for injecting a pulsed supersonic gas flux, including a first chamber (2) inside which the gas to be injected is found under pressure on either side of a free piston (4), the device comprising means (12) for setting this free piston into motion, connected to the first chamber and able to cause propulsion of the free piston (4), the device further including a supersonic nozzle (6) able to communicate with the first chamber via an aperture (8), and also including a valve (10) closing up the aperture (8) and able to be actuated by percussion of the free piston (4).