Magnetic field of heliotron with irregular helical coil pitch

The paper presents the results of numerical calculations on the magnetic field of a heliotron with a helical coil pitch L0, which comprises a helical coil section named as an L-section, where the helical coil pitch L differs from L0, i.e. L < L0. The calculations have shown that within the L-section the real preconditions exist permitting to form both the plasma core of passing plasma particles and of the SOL plasma boundary being at the increased distance from the wall in the high magnetic field region.