Greifswald 2009 – scientific programme

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P: Fachverband Plasmaphysik

P 15: Poster: Diagnostik

P 15.2: Poster

Wednesday, April 1, 2009, 17:30–19:30, Foyer des IfP

Effect and Correction of Jitter for Thermographic Diagnostics at ASDEX Upgrade — •Pascal de Marné, Albrecht Herrmann, and the ASDEX Upgrade Team — Max-Planck-Institut für Plasmaphysik, Garching, Deutschland

At ASDEX Upgrade different one- and two-dimensional thermographic systems are used for contactless temperature measurements of different parts of the vessel, as for example the lower divertor. The power deposition on the monitored parts is calculated from the time evolution of the measured surface temperature. For correct heat load results it is necessary that always the same area is imaged on a pixel, otherwise the temperature evolution of different locations is used for the heat load calculation. This results in heat load artifacts in particular for regions with strong lateral temperature gradients.

Even for normal operation conditions, the recorded temperature data is affected by jitter, for example due to vessel vibrations. During disruptions with its strong forces onto the vessel, the jitter is significantly stronger. Also planned movements like strokes of reciprocating probes can be treated as a kind of jitter regarding power deposition calculations. Since the causes of the jitter cannot be avoided, it is necessary to correct the recorded temperature data before calculating the power deposition. Correlation analysis based algorithms for a jitter correction in the subpixel range have been implemented for the diagnostics at ASDEX Upgrade. For the one-dimensional data the correction can be done fully automated whereas for the two-dimensional cameras a minor user input is necessary.