Enhancement of reactivity by RF

The enhancement of reactivity that can be gained from using auxiliary heating methods which transfer the power to fuel ions is investigated by using a transport code (JETTO) equipped with an RF package that computes the ion tails created by minority fundamental ion-cyclotron heating. The feasibility of ion-cyclotron heating scenarios is briefly examined from the point of view of absorption efficiency, power distribution among species and parasitic alpha -particle absorption. The main body of the work consists of the analysis of transport simulations of auxiliary heated plasmas. Methods resting on electron and ion heating are compared under three different confinement assumptions. In each case, the importance of RF-induced tail effects is also investigated. The differences between the electron and ion heating schemes are explained on the basis of a simple O-D power balance which summarizes the essential features of the JETTO simulations. It is concluded that significant benefit can be obtained from using ion heating methods in the case of reactors operating at moderate fusion Q's (10-40) and even more if the Q is lower. The relative inefficiency of electron heating results from the competition between electron transport losses and equipartition in the electron power channel.