Multichannel Langmuir probe for turbulence study in Heliotron J

Rev Sci Instrum. 2010 Oct;81(10):10E137. doi: 10.1063/1.3496980.

Abstract

New multichannel Langmuir probe system was developed and installed to Heliotron J. The objective of the new probe is to characterize basic turbulence property and the resulting transport in advanced helical configuration. The probe developed here consists of four sets of triple probe and one pin for floating potential measurement. Initial experiments in neutral beam heating plasma were conducted and fluctuation profile of radial and poloidal electric fields and Reynolds stress were estimated. For precise evaluation of the electric fields and Reynolds stress, a technique to compensate radial change of tilt angle between probe array and magnetic surface was proposed and applied to the initial results obtained in edge region of Heliotron J where the complicated magnetic structure exists.