<abstract xmlns="http://www.w3.org/1999/xhtml"><p> The COMPASS tokamak is equipped with the soft X-ray (SXR) diagnostic system based on silicon photodiode arrays shielded by a thin beryllium foil. The diagnostic is composed of two pinhole cameras having 35 channels each and one vertical pinhole camera with 20 channels, which was installed recently to improve tomographic inversions. Lines of sight of the SXR detectors cover almost complete poloidal cross section of the COMPASS vessel with a spatial resolution of 1-2 cm and temporal resolution of about 3 μs. Local emissivity is reconstructed via Tikhonov regularization constrained by minimum Fisher information that provides reliable and robust solution despite limited number of projections and ill-conditionality of this task. Improved border conditions and numerical differentiation matrices suppressing artifacts in reconstructed radiation were implemented in the code. Furthermore, a fast algorithm eliminating iterative processes was developed, and it is foreseen to be tested in real-time plasma control.</p></abstract>

The COMPASS tokamak is equipped with the soft X-ray (SXR) diagnostic system based on silicon photodiode arrays shielded by a thin beryllium foil. The diagnostic is composed of two pinhole cameras having 35 channels each and one vertical pinhole camera with 20 channels, which was installed recently to improve tomographic inversions. Lines of sight of the SXR detectors cover almost complete poloidal cross section of the COMPASS vessel with a spatial resolution of 1-2 cm and temporal resolution of about 3 μs. Local emissivity is reconstructed via Tikhonov regularization constrained by minimum Fisher information that provides reliable and robust solution despite limited number of projections and ill-conditionality of this task. Improved border conditions and numerical differentiation matrices suppressing artifacts in reconstructed radiation were implemented in the code. Furthermore, a fast algorithm eliminating iterative processes was developed, and it is foreseen to be tested in real-time plasma control.

Optimization of soft X-ray tomography on the COMPASS tokamak

Institute of Plasma Physics ASCR v.v.i., Faculty of Mathematics and Physics, Charles University in Prague, Za Slovankou 3, 18200 Praha 8, Czechia

Max-Planck-Institut für Plasmaphysik, Technische Universität Munchen, Boltzmannstraße 2, D-85748 Garching,

Optoelectronic Research Center, University of Southampton, University Rd, Southampton SO17 1BJ,

Nukleonika

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

{"article-title":"Optimization of soft X-ray tomography on the COMPASS tokamak"}

The COMPASS tokamak is equipped with the soft X-ray (SXR) diagnostic system based on silicon photodiode arrays shielded by a thin beryllium foil. The...

Optimization of soft X-ray tomography on the COMPASS tokamak

Article Category: Proceedings of the Summer School of Plasma Diagnostics Phdiafusion 2015: “Soft X-Ray Diagnostics for Fusion Plasma” Bezmiechowa, Poland, 16-20 June 2015

Published Online: Oct 26, 2016

Page range: 403 - 408

Received: Sep 03, 2015

Accepted: Nov 11, 2015

DOI: https://doi.org/10.1515/nuka-2016-0066

Keywords
soft X-ray, tomography, Tikhonov regularization, tokamak

© by Martin Imríšek

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Optimization of soft X-ray tomography on the COMPASS tokamak

Article Category: Proceedings of the Summer School of Plasma Diagnostics Phdiafusion 2015: “Soft X-Ray Diagnostics for Fusion Plasma” Bezmiechowa, Poland, 16-20 June 2015

Published Online: Oct 26, 2016

Page range: 403 - 408

Received: Sep 03, 2015

Accepted: Nov 11, 2015

DOI: https://doi.org/10.1515/nuka-2016-0066

Keywordssoft X-ray, tomography, Tikhonov regularization, tokamak

© by Martin Imríšek

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Keywords
soft X-ray, tomography, Tikhonov regularization, tokamak