Ripple burn control

The ripple contribution to the ion thermal conductivity is ideally suited in magnitude, temperature dependence, and spatial dependence to serve as a burn control mechanism. Furthermore, a considerable measure of automatic burn control results because of the radial shift of the plasma to a region of higher ripple. Unfortunately, the window in ripple values consistent with both ignition and a burn equilibrium is uncomfortably narrow, given the current lack of contact between the theoretical models of ripple transport and experimental observations. A survey is made of the techniques to vary the ripple and thus broaden the design window. One new technique is discussed in some detail: the use of ferromagnetic materials in the shield with magnetic properties which are sensitive functions of the operating temperature