In the Large Helical Device (LHD), an MHD equilibrium with both deep magnetic well and high magnetic shear in the plasma core region attracts much attention from a point of view of improved MHD stability and plasma confinement. In LHD, such an equilibrium can be realized by a large Ohkawa current induced by counter neutral beam injection. In a plasma with a net subtractive toroidal current of about -100 kA/T, the rotational transform is expected to be below zero around the magnetic axis. Numerical analysis of the LHD equilibrium is carried out by using the HINT code [1-4]. The HINT computation starts from the vacuum configuration with B₀=1.5 T and R₀=3.75 m, and the initial pressure profile given as p=p₀(1-s⁴)(1-s), where B₀ is the magnetic field strength at the magnetic axis, R₀ is the major radius of the axis, p₀ is pressure at the axis, and s is the normalized toroidal flux. We find that an LHD equilibrium with a zero rotational transform surface is possible to exist. In the field line structure, we see two or three islands near the center, where the number of the islands depends on its equilibrium beta value. The central island has a negative ł, and the others located around the central one have a zero rotational transform around an O-point of the central island. Here n is a toroidal mode number. The LHD equilibrium keeps the homoclinic-type structure [3,5] composed by the islands near the center, when β increases. We can consider that this field line structure is general for both helical and tokamak plasmas, because the toroidal mode number of the islands is zero.

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