Polyhelix magnets

Polyhelix magnets consist of a number of coaxially nested thin coils (helices), which are mechanically decoupled and electrically isolated with respect to each other. This construction technique shows advantages for both resistive and superconducting magnets: stresses are reduced and magnets with the same stress level for each helix, and therefore requiring less volume, can be built. We present the design and performance levels of two resistive polyhelix magnets which generated a maximum field of 22.3 T and 23.4 T in a 50 mm room temperature bore.