Buoyant magnetic flux tubes enhance radiation in Z pinches

In numerous experiments, magnetic energy coupled to strongly radiating Z-pi nch plasmas exceeds the thermalized kinetic energy, sometimes by a factor o f 2-3. We demonstrate that the enhanced energy coupling may be due to the b uoyancy rise, of toroidal magnetic flux tubes converging to the axis throug h. the unstable pinch plasma. We derive an explicit formula for the enhance d dissipation rate and apply this formula to reconsider an old problem of p ower balance in a steady-state Z pinch, and then to analyze a new challenge of producing K-shell 3 to 10 keV radiation in long-pulse Z-pinch implosion s.