Gas laser resonator

The present invention aims to prevent, in a gas laser resonator, the deterioration of the quality of discharges produced by reduction of the pressure in the discharge chamber (2) as well as the inflow of impurity gases, such as air, into the discharge chamber (2). This is produced by providing a buffer chamber (12), different from the discharge chamber (2). A bracket (6) is attached to one end of a tube (1) comprising the discharge chamber interposing a sealing part, e.g. a gasket, (13) only for sealing the opening of the discharge chamber (2) and a gasket (14) for sealing both openings of the discharge chamber (2) and the buffer chamber (12). A glass plate (8) and a further bracket (9) are attached to the other end of the tube (1) interposing a gasket (15) only for sealing the opening of the discharge chamber (2) and a gasket (16) for sealing both openings of the discharge chamber (2) and the buffer chamber (12). The pressure in the buffer chamber (12) is set lower than the one of the discharge chamber (2) and than the atmospheric pressure so that to decrease the inflow of the impurity gases toward the discharge chamber (2).