Measurement of stochastic magnetic field in Heliotron E

Measurements of stochastic magnetic field in Heliotron E were made in 1994. In the standard configuration at low B field (500G at the magnetic axis), the candidates for the last closed magnetic field were found at the positions of iota/2pi=1.7,1.9 and 2.2. In the case of limiter insertion, it was found that the limiter head determines the position of the last closed magnetic surface. By comparison between the value of the current to the limiter and the calculated connection length to the limiter, it was found that there is a strong correlation between them. As for constructing a theoretical model, a model based on the neoclassical diffusion theory could explain the experimental results in the standard configuration to some extent