A tokamak current can be sustained using rf waves for transformer recharging at low density and high-Z with high efficiency if the resistivity is kept high enough during the radio frequency recharging stage. At the same time, operation in the hot ion mode via alpha channeling increases the effective fusion reactivity. The two separate inventions can be made to work synergistically. Specifically, by operating the tokamak in a low-density recharge phase, the lower hybrid wave penetrates the plasma more effectively. High reactivity is obtained by operation in the hot ion mode through the alpha channeling technique. Then, by using a high temperature relaxation stage, not only is the plasma current sustained longer without any current drive during that stage, but also the fusion reactivity can be made larger by operating alpha channeling at high electron temperatures.
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