The hysteresis characteristic in the structure of the radial electric field in helical toroidal plasmas is examined using a one-dimensional transport model. The response of the radial electric field Er against the change in the average plasma density ⟨n⟩ is investigated. The hysteresis of Er against the rise and fall of ⟨n⟩ is studied. In the case of a slow change in ⟨n⟩ (i.e. if the change is much slower than the energy confinement time), the hysteresis cannot be found in a one-dimensional analysis, in contrast to its evaluation by use of a local point model. If one studies the dependence of Er at a fixed position robs on the density, Er(robs)[n], the bifurcation nature can be seen in a rapid change of the curvature d2Er(robs)/dn2, where robs denotes the radial observation point. A hysteresis in the response of Er to ⟨n⟩ can be observed, if the characteristic time of the temporal change is much shorter than the typical confinement time.
Density dependence of transient electron thermal transport property in LHD