Ripple reduction poloidal field coils for tokamak fusion reactors

Ripple Reduction Poloidal Field (RRPF) coils consist of dipole magnetic coils placed above and below the plane of a tokamak plasma in order to produce the vertical and shaping field needed for plasma equilibrium and at the same time to reduce the magnetic ripple from discrete toroidal field (TF) coils. A design is presented which reduces the ripple produced by 8 TF coils with INTOR dimensions from more than 2% to less than 0.1% throughout the plasma. With this design, it is found that the poloidal field from the coils can be adjusted independent of the ripple reduction. Coil currents are found for which there are computed free-boundary plasma equilibria with elongated cross section