I. THE GENERAL APPROACH Some important applications of High Power Gas Flow and Chemical Lasers (HPGCL) are aimed to ground level operations. HPGCL are understood here as open cycle machines. It means that after the laser cavity their exhaust gases run out to the ambient atmosphere. Exhaust gas products after resonator cavity cannot be evacuated directly to atmosphere. The atmosphere pressure on the sea level exceeds the cavity pressure by 1 0 -20 times for CO2 gasdynamic lasers (GDL) and by 150 -200 times for chemical oxygen-iodine lasers (COIL). Combustion Driven CO2 GDL only can operate with-. . . . . . Pressure Recovery Systemout energy additions, using ordinary passive diffusers. However, and in these cases, the whole HPGCL system scale is determined, by the diffusers' dimensions. Meanwhile, the ground operation of High Power HF/DF-CL and COIL requires already "active" Pressure Recovery Systems (PRS): large-scale complexes, including diffusers and high-energy ejectors. Fig. 1 demonstrates a correlation between scales of the HF/DF-chemical laser and it pressure recovery system. Even without component supply subsystems (balloons, tanks, pipes, accessories, etc.) the scales are non-compared. For COIL the difference becomes more significant. Approximate estimates confirm also, that the ejecting gas flow rate of ejector stations may exceed the laser components' summary gas flow rate by many tens times [1].It changes seriously the general estimations the HPGCL effectiveness. There are some results of such calculations on Fig. 2. No doubt, that specific energetic effectiveness of the HF/DF-CL and COIL with and without the PRS components is to be very different.The HPGCL and PRS have to be considered as indivisible, strictly integrated systems. Their combined analysis, aimed to a search of optimal technical solutions, has to take into account many links and interactions, except ofthe additional expenditures ofenergy and components.The present papers contains a review of various technical concepts DF and schematic solutions aimed to practical uses for some real applications, Fig. 2 meanwhile, physical processes in the diffusers and supersonic ejectors of the HPGCL PRS are considered more precisely in the [2, 3].
II. DIFFUSERSIndependently on a pressure level into cavities, gas flows of all considered HPGCL are supersonic, therefore, the streams' kinetic energy may be applied for the PRS operation. However, this energy, is not enough for direct exhaust of the laser gases to ambient atmosphere. Hence, it is necessary providing of an energy addition to the stream with agency of ejector and compressor technologies. In spite of some known interest to supersonic mixing ejectors [4], all presented bellow data are related to traditional schemes.Characteristics ofthe supersonic laser gas mixture flows after DF and COIL cavities are given in [2]. Parameters of the laser flows are close enough, so, at least, from constructive point of view, diffusers for both types of the lasers have to be similar. A supersonic flow slowdown pr...
