The evolution of a high-ß plasma after the initial dynamic phase is described by a multifluid (electrons, hydrogenic ions, neutrals, and impurities) model for a belt-pinch configuration. The numerical results obtained from the model agree with experimental findings from th e Garching Belt Pinch II. The power balance i s dominated by radiation losses for impurity percentages of 1-3%. Neutrals play a role for plasma densities ≲ 1014 cm−3 . Energ y confinement times, and thus decay times for ß in the ms-range should be obtainable. An optimization is presente d for plasmas whose initial densities, temperatures, and impurity contents are produced by shock heating