The flattening of the electron density profiles due to the static magnetic island is observed when the n/m = 1/1 perturbation field is applied by the external coil. The iso-density widths are estimated from the model fitting analysis. The temporal history of the iso-density width and its dependence on normalized collision frequency and plasma β are estimated from a single shot. The iso-density width increases as the external perturbation field increases. Although determination errors are not small compared with the dynamic range of the estimated iso-density width, the following tendencies are observed. The iso-density width shows positive dependence on logarithm of normalized collision frequency and negative dependence on β.
Effect of β and collisionality on the vacuum magnetic field islands in stellarators