Performance of line-divergence subsection supersonic diffuser for COIL

In chemical lasers, the supersonic diffuser plays an important role in pressure system. This paper introduces some experimental results of line-divergence subsection diffuser for COIL. Preliminary study shows supersonic diffuser with right divergent angel can achieve good ability of pressure recovery and isolated optical cavity fluid field. Diffuser efficiency can be greatly improved by means of setting proper thickness vertical vans along the direction of inner width of diffuser. In addition, optimized shape of labium mouth and manpower roughness in the internal cavity of diffuser entrance can improve wall pressure distribution and diffuser efficiency．