Electromagnetic loads prediction and structural analysis of HL-2M toroidal field coils

The HL-2M toroidal field (TF) system comprises 20 D-shaped coils each 5.08 m high, 2.961 m wide. The TF coils are designed for a maximum toroidal magnetic field of 3 T at R = 1.78 m and consists of 140 turns of copper. Finite element code has been used to predict the electromagnetic (EM) loads for normal operation and engineering test scenarios. The results show that the in-plane loads produce a net centering force with a maximum value 2275 tons on each coil and expand the outer coil bundles. The lateral forces are caused by the interaction between the poloidal magnetic field and the TF coil current. For a 3 MA plasma currents operation, the lateral forces cause a torque about 1488 t.m on the whole 140 turns. If the plasma disrupts suddenly, the torque may be increased to 4237 t.m. As a consequence of the EM loads, high inter-turn shear stress about 25 MPa may be induced in the inner corner of the TF bore and the outer arc sections. The stress in copper conductor about 145 MPa may be caused by the high tension and shear force in the demountable joints region. Many design iterations have been carried out to optimize the support structure to satisfy the desired 100000 pulses operation goal of TF coils.