An improved fusion reactor design with provision for supplying plasma fuel inside a model reactor without consuming additional power in the process. Embodiments provide free choice of useful fuels from the full range of fusible isotopes. Other embodiments provide means of selectively extracting up-scattered electrons from the plasma, followed by replacing them with electrons of corrected energy. Computer simulations show fusion reactors constructed with these inventive improvements will demonstrate increased net-power compared to other fusion reactors of similar size. The Specification of the invention leads immediately to staged reactor development, starting from small-scale model-reactors, moving on to larger and larger scale models, culminating with commercial power plants.