The demand for increased productivity in high vacuum plasma processing chambers calls for greater vacuum system throughput. Pump manufacturers have responded by refining turbomolecular and drag pump designs to raise speed and operating temperature limits. Plasma pumps, in a modular design with no moving parts, offer an alternative to rotating machinery for transport of large quantities of gas, especially light or inert gases. The concept depends on the Lorentz force j x B to generate a pressure gradient, directed from the inlet to the outlet of each of an array of channels. The transverse magnetic field B is provided by permanent magnets incorporated in the channel array. Microwave electric fields, parallel to B, form the plasma within the channel array. A steady electric field E, between stainless steel electrodes in each channel, drives the transverse current density j, such that j x B is always directed from the inlet to the outlet region of each channel. Measurements of compression ratios and of throughput per channel vs. pressure (in the range 0.001 to 1 Torr) in evolving laboratory models employing these concepts are reported, together with an approach to modelling transport of plasma and neutrals in the channels.