Effects of the Bumpy Field Component on the Bootstrap Current in L = 1 Helical Plasmas

Effects of the bumpy field component on the bootstrap current in the low-collisionality regime are discussed for L = 1 helical plasmas. It is usually considered that the bumpy field component or toroidal mirror ratio suppresses the bootstrap current in helical plasmas since it is a symmetry-breaking component. In the Heliotron J device, however, it has been observed that the direction of the bootstrap current can be changed according to the magnitude of the bumpy field component. In this study, we calculate the bootstrap current in the low-collisionality regime using a model magnetic field spectrum and discuss the condition under which the reversal of the bootstrap current direction occurs.