The separation probe

The separation probe utilizes the bow shock wave and/or the pressure gradient (barodiffusion) induced by a probe operating in a supersonic stream. The gas removed from the probe stagnation region and collected from the sampling orifice, is enriched in the heavier species. Although the emphasis is on the physics of the separation effect, other relevant problem areas, including economics, are also mentioned and discussed in this paper. From experimental and even theoretical works on gas and isotope mixtures, carried out in the U.S.A. and in France, the following points are analysed: physical principles; optimization of single probes and probe arrays; influence of expansion ratio, pressure recovery, flow velocity, and rarefaction