AEROTHERMIC CHARACTERIZATION OF A HIGH-POWER FAST AXIAL-FLOW CO2-LASER

Because the structure of the flow in glow discharge tubes for high-pow er CO2 lasers is one of the main physical processes to control in orde r to avoid arcing, an experimental procedure for studying the velocity and temperature fields in such tubes was performed. Two kinds of inje ction system have been studied. For the first one, the gas mixture is injected by a single sonic nozzle located on the axis of the tube. Bec ause the power of the laser may be increased by associating several tu bes in line, the other injection system consists of a series of 12 hol es radially arranged in order to move injectors away from the axis. Fo r both cases, the axial mean time velocity profile was measured (witho ut electric discharge) using a laser Doppler anemometry technique in s everal sections of the discharge tube. The temperature held was invest igated during the discharge by using a special thermofluorescent probe . It is found that turbulence facilitates the homogenization of the di scharge.