HELIOS: a helium line-ratio spectral-monitoring diagnostic used to generate high resolution profiles near the ion cyclotron resonant heating antenna on TEXTOR.

Radial profiles of electron temperature and density are measured at high spatial (similar to 1 mm) and temporal (>= 10 mu s) resolution using a thermal supersonic helium jet. A highly accurate detection system is applied to well-developed collisional-radiative model codes to produce the profiles. Agreement between this measurement and an edge Thomson scattering measurement is found to be within the error bars (less than or similar to 20%). The diagnostic is being used to give profiles near the ion cyclotron resonant heating antenna on TEXTOR to better understand RF coupling to the core. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4739236]