Electromagnetic stress analysis of the TF coil on HL-2M tokamak

In order to obtain enhanced plasma confinement parameters the construction of the HL-2A modification (HL-2M) is now being designed. For the HL-2M all poloidal field (PF) coils are located outside the TF magnets and newly constructed, so the out-of-plane forces on the TF coil are highly increased as compared with HL-2A. At the same time we make use of the existing TF coils of the HL-2A, each of which moves outwards along its radial direction to increase major radius from 1.65 to 1.8 m and therefore the D-shape of TF coil on the HL-2M no longer minimizes bending caused by the self-forces of the coil system. This rearrangement of the TF coils leads to a change in coil stresses, especially in shear stresses.The maximum Tresca stresses on the winding pack and coil case are 36.5 and 42.1 MPa, respectively. The maximum shear stress in the winding pack is about 18.2 MPa. Both stresses are within the allowable limits.The ferritic inserts will be designed for ripple reduction to improve the confinement of fast ions in the experiments. The TF reduction ripple is less than 0.3% in the plasma region.