A controlled fusion process is provided that can produce a sustained series of fusion reactions: a process that (i) uses a substantially higher reactant density of the deuterium and tritium gases by converging cationic reactants into the higher reaction density at a target cathode rather than relying on random collisions, the converging producing a substantially higher rate of fusion and energy production; (ii) uses a substantially lower input of energy to initiate the fusion; (iii) can be cycled at a substantially higher cycle frequency; (iv) has a practical heat exchange method; (v) is substantially less costly to manufacture, operate, and maintain; and, (vi) has a substantially improved reaction efficiency as a result of not mixing reactants with products.