A new design method for the modularization of helical coils of a stell
arator type has been proposed. This is an extension of the interchange
able module stellarator (IMS) method, and L = +/-2 helices with differ
ent pitch angles are utilized. This modular coil system exerts less er
ror field effects on magnetic properties, so it may have large magneti
c surfaces. The magnetic axis exists nearly at the coil center without
any additional fields. It may have larger transform than that designe
d from the original IMS method.