Some observations concerning alpha instabilities and driven tokamak reactors

While much research is needed to assess the reality and consequences of alpha-induced instabilities, crude transport estimates for the TAE mode indicate that as little as 10 percent of the alpha energy would be deposited in steady-state. Even so, CIT and the ITER technology phase would meet their minimal goals of Q = 5 if only the alphas themselves are ejected and not the fuel itself. Higher gain up to Q ∼ 20 may be possible in driven reactors of a different design, depending on the effects of aspect ratio and other geometric features on confinement. Very high gain still requires alpha testing. 5 refs