Broad‐Band Time‐Resolved Near Infrared Spectroscopy in the TJ‐II Stellarator

Abstract

First experimental results on broad‐band, time‐resolved Near Infrared (NIR;here loosely defined as covering from 750 to 1650 nm) passive spectroscopy using a high sensitivity InGaAs detector are reported for the TJ‐II Stellarator. Experimental set‐up is described together with its main characteristics, the most remarkable ones being its enhanced NIR response, broadband spectrum acquisition in a single shot, and time‐resolved measurements with up to 1.8 kHz spectral rate. Prospects for future work and more extended physics studies in this newly open spectral region in TJ‐II are discussed. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Plasma diagnostic systems and methods used on the stellarator TJ-II

“…good temporal and/or spatial resolution. Examples of electromagnetic systems include a 16-channel electron cyclotron emission radiometer to obtain electron temperature, T e , values at discrete radial positions inside ρ = 0.75 (ρ = a/r, where a is average plasma minor radius) with 10 μs temporal resolution along discharges [9], infrared, visible, ultraviolet and vacuum ultraviolet spectrometers to identify and follow the temporal evolution of line emissions from impurities located in edge and core regions [10][11][12], Balmer H 𝛼 monitors positioned at different toroidal positions [13], plus 2 multiple-filter soft X-ray systems to follow the temporal evolution of the core T e with 1 ms resolution and to estimate bremsstrahlung emissions needed to evaluate impurity content, i.e., Z eff [14]. In addition, tomographic reconstructions of total plasma emissivity, with high temporal resolution, are made using signals from three 20-channel pinhole cameras (absolute extremeultraviolet type fast photodiode arrays) located in the same sector.…”