How hot must plasma be to conduct electricity effectively in an MHD generator?

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magnetohydrodynamic power generator Comparison of the operating principles of (A) a turbogenerator and (B) an MHD generator.

For a magnetohydrodynamic (MHD) power generator to operate competitively with good performance, the plasma must maintain an electrical conductivity at temperatures above approximately 1,800 K (about 1,500 °C, or 2,800 °F).1

To achieve the necessary electrical conductivity—typically 10 to 50 siemens per metre—a small amount of a readily ionizable alkali material, known as a "seed" (such as cesium, potassium, or sodium), is injected into the hot gas. While thermal ionization can be used to generate power, the process is generally considered finished when the gas temperature drops to about 2,500 K (about 2,200 °C, or 4,000 °F).12