Mach disc

Schematic diagrams of (a) the ICP-MS interface and (b) the supersonic expansion formed in the expansion chamber, showing the barrel shock and position of the Mach disc.

Mach disc. See Ion sampling Magnetic sector. See Mass analyser Mass analyser ... 

The supersonic flow is terminated by a barrel shock, a cylindrical shock and a curved Mach disc with triple points at their intersections (Mach reflexion). The cylindrical shock results from the evaporation flow of the liquid being almost perpendicular to the jet axis. 

Figure 1.5 A stylised cross section through the expansion region illustrating the location of the barrel shockwave and the Mach disc.

The multi-element kneading blocks are assembled of discs of different thickness (to adjust the ratio of dispersive to distributive mixing) and displacement angle (see Table 9.10). Blocks constmcted from the same number of elements, but of different thickness also behave differently. Wide discs provide mach greater sharing action than the narrow ones, i.e., the former provides dispersive mixing while the latter the distributive one. As the disc thickness in the block decreases its conveying capability increases. 

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