A theoretical model of feedback instability is proposed to explain the mechanism of correlation between the detachment and the cross-field plasma transport. It is shown that the feedback instability on the detached divertor plasma can be induced in a certain condition in which the volume recombination frequency is larger than the ion cyclotron frequency in the recombination region. Further, the density gradient and the electric field in the direction perpendicular to the magnetic flux surface are not zero in the condition. The feedback instability can provide the cross-field plasma transport in the boundary layer of magnetic fusion torus devices. Furthermore, the properties of the radial transport observed in the NAGDIS-II linear device experiment are compared with the estimation by the feedback instability model. The dependence of the feedback instability mode on the total collision frequency and the recombination coefficient and the density gradient has been also investigated. Although the dependency on the total collision frequency and the recombination coefficient for the typical fusion torus device case is opposite to that for the NAGDIS-II case, the represented dependencies show the reasonable tendency in each case.
Experimental verification of the influence of the Hall effect on the penetration of a high-frequency travelling magnetic field into a plasma in the "Delta" device