I know that confinement and stability are a big issues when it comes to harnessing fusion power in a controlled fashion, but what if we could do away with the stability constraint? (sorry if this is completely unfeasible, I don't really know very much about plasma and discharge physics). My idea is to confine the plasma within a magnetic tube and apply heat to it whilst it accelerates out of the tube (much like many proposed plasma rocket schemes). I assume that as long as the plasma is confined within the tube at a critical density and temperature (whilst accelerating towards the "outlet"), the plasma will fuse and produce a net energy surplus. The superheated hot gases could then be allowed to mix and dissipate with air in a large air breathing turbine assembly (possibly with a forward compressor stage) to drive a large turbine and produce power. Crude I know, but is it feasible? I feel that such a scheme would encounter mostly engineering problems, rather than scientific problems which are showstoppers for most other fusion power plant designs. Given a large enough turbine and confinement area, I can't see why this isn't possible.