STABILIZATION OF THE RESISTIVE WALL MODE USING A FAKE ROTATING SHELL

Tokamak plasma performance can, in theory, be greatly improved if the so-called ''resistive wall mode'' is stabilized. This can be achieved by spinning the plasma rapidly, but such a scheme would be difficult t o implement in a reactor setting. A more promising approach is to appl y external feedback,in order to make a resistive shell placed around t he plasma act like a perfect conductor. A scheme is outlined by which a network of feedback controlled conductors surrounding the plasma can be made to act like a rotating shell This fake rotating shell combine d with a stationary conventional shell (e.g., the vacuum vessel) can c ompletely stabilize the resistive wall mode. The gain, bandwidth, curr ent, and power requirements of the feedback amplifiers are extremely m odest. A previously proposed Stabilization scheme (the intelligent she ll) is also investigated, and is compared with the fake rotating shell concept. The main disadvantage of the former scheme is that it requir es a high gain. (C) 1996 American Institute of Physics.