@article{oai:nifs-repository.repo.nii.ac.jp:00000393,
 author = {Imagawa,  Shinsaku and SAGARA,  Akio and WATANABE,  Kiyomasa and SATOW,  Takashi and SATOW,  Takashi and MOTOJIMA,  Osamu and IMAGAWA,  Shinsaku and SAGARA,  Akio and WATANABE,  Kiyomasa and MOTOJIMA,  Osamu},
 journal = {Journal of Plasma and Fusion Research SERIES, Journal of Plasma and Fusion Research SERIES},
 month = {Jan},
 note = {The electromagnetic force on a helical coil becomes smaller by decreasing the coil pitch parameter which is the angle of the coil to the toroidal direction. This makes it possible to enlarge the central toroidal field or to simplify the supporting structures of the coil. The plasma minor radius, however, becomes smaller with the pitch parameter, and a higher field is necessary to attain the same plasma performance. Another important item in a helical reactor is the distance between the helical coil and the plasma to gain enough space for blankets. In order to reduce the mass of the coil supports, a lower aspect ratio is advantageous, and an optimum value of the pitch parameter will exist around 1.2 and 1.0 for the helical systems of the pole numbers of 2 and 3, respectively.},
 title = {Magnetic Field and Force of Helical Coils for Force Free Helical Reactor (FFHR)},
 volume = {Vol.5},
 year = {2002}
}