Measurements of Oxygen Ion Spectra for Estimation of Electric Field Profiles in Cylindrical Plasmas

Abstract

Electric field profiles play an important role in the improvement of plasma confinement. It is essential to develop techniques to measure the electric field profiles in each region of a fusion device. We have developed a technique to measure the electric field profiles in cylindrical plasmas by measuring the Doppler shift of the CII spectrum. Recently, we have developed a collisional-radiative model for the lower charge state of oxygen ions. The oxygen emissions are stronger than those of carbon in GAMMA 10. In order to achieve a higher resolution for the electric field measurements, the technique for measuring the electric field profiles was improved by using the measurements of the oxygen spectra and the calculation of the newly developed collisional-radiative model. The electric field profile was successfully obtained under the condition of a weak electric field.