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6 results on '"Stober, J.K."'

2. Radiation transport modelling for the interpretation of oblique ECE measurements

Author

Denk, S.S., Fischer, R., Maj, O., Poli, E., Stober, J.K., Stroth, U., Vanovac, B., Suttrop, W., Willensdorfer, M., Team, ASDEXUpgrade, Science and Technology of Nuclear Fusion, and ASDEX Upgrade Team, Max Planck Institute for Plasma Physics, Max Planck Society

Subjects
Physics, Electron density, QC1-999, Cyclotron, Oblique case, Astrophysics, Electron, Radiation, 01 natural sciences, 010305 fluids & plasmas, Computational physics, law.invention, Ray tracing (physics), ASDEX Upgrade, law, Physics::Plasma Physics, 0103 physical sciences, Electron temperature, 010306 general physics
Abstract

The electron cyclotron emission (ECE) diagnostic provides routinely electron temperature (Te) measurements. At ASDEX Upgrade an electron cyclotron forward model, solving the radiation transport equation for given Te and electron density profile, is used in the framework of integrated data analysis. With this method Te profiles can be obtained from ECE measurements even for plasmas with low optical depth. However, due to the assumption of straight lines of sight and an absorption coefficient in the quasi-perpendicular approximation this forward model is not suitable for the interpretation of measurements by ECE diagnostics with an oblique line of sight. Since radiation transport modelling is required for the interpretation of oblique ECE diagnostics we present in this paper an extended forward model that supports oblique lines of sight. To account for the refraction of the line of sight, ray tracing in the cold plasma approximation was added to the model. Furthermore, an absorption coefficient valid for arbitrary propagation was implemented. Using the revised model it is shown that for the oblique ECE Imaging diagnostic at ASDEX Upgrade there can be a significant difference between the cold resonance position and the point from which most of the observed radiation originates.

Published
2017

3. Commissioning of inline ECE system within waveguide based ECRH transmission systems on ASDEX upgrade

Author

Donné A.J.H., Amerongen F.J., de Baar M.R., Meo F., van den Brand H., van den Braber R., Doelman N., Kasparek W., Bongers W.A., Elzendoorn B.S.Q., Erckmann V., Goede A.P.H., Giannone L., Grünwald G., Hollman F., Kaas G., Krijger B., Michel G., Lubyako L., Monaco F., Noke F., Petelin M., Plaum B., Purps F., ten Pierik J.G.W, Schüller C., Slob J.W., Stober J.K., Schütz H., Wagner D., Westerhof E., and Ronden D.M.S.

Subjects
Physics, QC1-999
Abstract

A CW capable inline electron cyclotron emission (ECE) separation system for feedback control, featuring oversized corrugated waveguides, is commissioned on ASDEX upgrade (AUG). The system is based on a combination of a polarization independent, non-resonant, Mach-Zehnder diplexer equipped with dielectric plate beam splitters [2, 3] employed as corrugated oversized waveguide filter, and a resonant Fast Directional Switch, FADIS [4, 5, 6, 7] as ECE/ECCD separation system. This paper presents an overview of the system, the low power characterisation tests and first high power commissioning on AUG.

Published
2012
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4. Combined electron cyclotron emission and heating for the suppression of magnetic islands in fusion plasmas

Author

van den Brand, H., de Baar, M.R., Hennen, B.A., Oosterbeek, J.W., Bongers, W.A., Westerhof, E., Kasparek, W., Doelman, N., Klop, W.A., Giannone, L., Stober, J.K., Monaco, F., Schütz, H., Wagner, D., van den Brand, H., de Baar, M.R., Hennen, B.A., Oosterbeek, J.W., Bongers, W.A., Westerhof, E., Kasparek, W., Doelman, N., Klop, W.A., Giannone, L., Stober, J.K., Monaco, F., Schütz, H., and Wagner, D.

Abstract

In a tokamak, magnetic islands need to be suppressed. Suppression is possible with electron cyclotron heating (ECH), which can be positioned using electron cyclotron emission (ECE) temperature measurements. A set-up to detect ECE in the line of sight of ECH has been built for the TEXTOR tokamak and the ASDEX Upgrade tokamak. In TEXTOR, a dielectric filter was used to separate low power ECE from high power ECH and successful aiming of ECH and suppression of a magnetic island could be demonstrated. At ASDEX Upgrade, a fast directional switch (FADIS) was used to separate ECE from ECH. Measurements of magnetic islands at ASDEX Upgrade are presented. The applicability of these measurements for magnetic island detection is discussed.

Published
2015

5. Commissioning of inline ECE system within waveguide based ECRH transmission systems on ASDEX upgrade

Author

Bongers, W.A., Kasparek, W., Doelman, N., van den Braber, R., van den Brand, H., Meo, F., de Baar, M.R., Amerongen, F.J., Donné, A.J.H., Elzendoorn, B.S.Q., Erckmann, V., Goede, A.P.H., Giannone, L., Grünwald, G., Hollman, F., Kaas, G., Krijger, B., Michel, G., Lubyako, L., Monaco, F., Noke, F., Petelin, M., Plaum, B., Purps, F., ten Pierik, J.G.W., Schüller, C., Slob, J.W., Stober, J.K., Schütz, H., Wagner, D., Westerhof, E., Ronden, D.M.S., Bongers, W.A., Kasparek, W., Doelman, N., van den Braber, R., van den Brand, H., Meo, F., de Baar, M.R., Amerongen, F.J., Donné, A.J.H., Elzendoorn, B.S.Q., Erckmann, V., Goede, A.P.H., Giannone, L., Grünwald, G., Hollman, F., Kaas, G., Krijger, B., Michel, G., Lubyako, L., Monaco, F., Noke, F., Petelin, M., Plaum, B., Purps, F., ten Pierik, J.G.W., Schüller, C., Slob, J.W., Stober, J.K., Schütz, H., Wagner, D., Westerhof, E., and Ronden, D.M.S.

Abstract

A CW capable inline electron cyclotron emission (ECE) separation system for feedback control, featuring oversized corrugated waveguides, is commissioned on ASDEX upgrade (AUG). The system is based on a combination of a polarization independent, non-resonant, Mach-Zehnder diplexer equipped with dielectric plate beam splitters [2, 3] employed as corrugated oversized waveguide filter, and a resonant Fast Directional Switch, FADIS [4, 5, 6, 7] as ECE/ECCD separation system. This paper presents an overview of the system, the low power characterisation tests and first high power commissioning on AUG.

Published
2012

6. Progress and First Results With the New Multifrequency ECRH System for ASDEX Upgrade

Author

Wagner, D.H., primary, Stober, J.K., additional, Leuterer, F., additional, Sips, G., additional, Grunwald, G., additional, Monaco, F., additional, Munich, M.J., additional, Poli, E., additional, Schutz, H., additional, Volpe, F., additional, Treutterer, W., additional, Zohm, H., additional, Franke, T., additional, Thumm, M., additional, Heidinger, R., additional, Gantenbein, G., additional, Meier, A., additional, Kasparek, W., additional, Lechte, C., additional, Litvak, A.G., additional, Denisov, G.G., additional, Chirkov, A., additional, Tai, E., additional, Popov, L., additional, Nichiporenko, V., additional, Myasnikov, V., additional, Solyanova, E., additional, and Malygin, S., additional

Published
2009
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