Title: Simple measure of merit for fusion feasibility
Abstract: A simple merit factor for fusion related experiments is discussed in terms of several fusion goals and compared with past and present experimental achievements. The merit factor is taken to be M = log 10/sup 10/ k, where k is the four-factor fusion formula (f eta epsilon p) and represents the fusion energy multiplication factor defining ignition for k greater than or equal to 1 or M greater than or equal to 10. The value of k can in most present cases be approximated by f, the thermal energy utilization factor, which equals the ratio of the alpha particle fusion power to the thermal power losses from the plasma. For upcoming large tokamak experiments, such as TFTR, the fast fusion factor epsilon due to beam-plasma reactions may appreciably exceed unity and thus reduce the Tn tau/sub E/ requirements for ignition through f. In the past 20 years, M has increased by six units and k or f by 10/sup 6/.