I agree with many of Jim's views. there is however one big issue for stellarators--particularly modular coil ones--the divertor. The poloidal divertor in a tokamak is axi-symmetric, and geernally speaking there aren't many energetic ions on weird orbits. nevertheless, even in a tokamak, true steady state at high power density has not been demonstrated, and one has to worry that the divertor region may not survive long enough. The situation for a stellarator is worse, even for a torsatron-heliotron, because of the higher level of energetic ions on loss orbits. For a modular device this is even worse because the divertor will not be continuous and there will be edges. The siltuation is ameliorated somewhat by the higher density at which the stellarators can operate.
I agree with many of Jim's views. there is however one big issue for stellarators--particularly modular coil ones--the divertor. The poloidal divertor in a tokamak is axi-symmetric, and geernally speaking there aren't many energetic ions on weird orbits. nevertheless, even in a tokamak, true steady state at high power density has not been demonstrated, and one has to worry that the divertor region may not survive long enough. The situation for a stellarator is worse, even for a torsatron-heliotron, because of the higher level of energetic ions on loss orbits. For a modular device this is even worse because the divertor will not be continuous and there will be edges. The siltuation is ameliorated somewhat by the higher density at which the stellarators can operate.