Optimization calculations of polyhelix coils for hybrid magnets
In order to generate very high, steady magnetic fields for research in solid-state physics one can combine a high-power resistive magnet with an outer superconducting coil. If magnetic fields above 30 Tesla have to be produced it is advisable to use a water cooled polyhelix copper coil as an inner part of such a hybrid magnet. An algorithm is described which allows the optimization of the design paramaters of a polyhelix coil in an external magnetic field with respect to dimensions and material for various values of the heat flux. The calculations show that with an outside field of 13 Tesla generated by a Nb3Sn−NbTi coil and with a 10 MW polyhelix magnet made of Cu (Al2O3) and Cu−Ag continuous magnetic fields around 40 Tesla may be generated in a 3 cm room temperature bore.
