Finite beta effects in quasihelical stellarators

An analytic expansion about a magnetic axis is applied to investigate finite beta effects such as bootstrap current on toroidal plasma equilibria which approximate quasihelical symmetry (QHS). It is found that quasihelically symmetric configurations can be found through the second order in terms of a helical inverse aspect ratio ε, even with the inclusion of a bootstrap current on the magnetic axis. Permitting the on-axis rotational transform to decrease as the on-axis bootstrap current is increased has little effect on the shape of the QHS flux surfaces. However, shifting the position of the magnetic axis in order to maintain the on-axis transform causes a stronger change in the QHS flux surface shape, especially axis shifts in the major radial direction