The circuit breaker using the two-phase state of a gas to improve the breaking properties

The invention relates to an arc extinguishing chamber (1) current for medium or high voltage circuit breaker extending along a longitudinal axis (XX ') and comprising: - a pair of arcing contacts (4, 5) whose at least one (5) is movable along the longitudinal axis (XX '); - a nozzle (6) arc blow, - a blast chamber (7), the volume V2 is fixed and which opens to the inside of the blast nozzle, - a compression chamber (8) arranged substantially behind the arcing chamber, and means (73, 81) for communicating the interior volume of this compression chamber (8) and that of the arcing chamber (7), - means (14, 15, 50), arranged substantially behind the compression chamber (8) for supplying liquid or in the compression chamber (8), either directly into the blast chamber (7).