A new approach for vacuum surface mapping in Helitron E

Wall boronization was applied in Heliotron E with special reference to the study of impurity and recycling control in the helical system. However this technique was also found to work as an advantageous tool to enhance the diagnostic sensitivity of the beam impedance method for measuring the edge and divertor field line structure. In this paper we describe a new approach to the beam impedance method that utilizes the wall boronization. (orig.)