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First mirror contamination studies for polarimetry motional Stark effect measurements for ITER
KTH, Superseded Departments, Physics.
KTH, Superseded Departments, Physics.ORCID iD: 0000-0001-7389-5501
2004 (English)In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 75, 3446-3448 p.Article in journal (Refereed) Published
Abstract [en]

The motional Stark effect (MSE) diagnostic on the International Thermonuclear Experimental Reactor will need to guide the light through a labyrinth of mirrors to provide neutron shielding. Knowledge of how the mirrors change the polarization is essential for accurate determination of the q profile. The optical properties of the plasma facing mirror are also expected to change with time due to deposition/erosion. For the purpose of examining this experimentally a detector system, identical to the JET MSE system, using twin photoelastic modulators was constructed. Measurements have been performed on freshly prepared mirrors, on mirrors after exposure to plasmas in Tore Supra, and labyrinth designs. The result shows a significant effect on the optical properties and demonstrate the need for in situ monitoring. The measured properties of the labyrinth closely follow the Mueller matrix formalism. With a correct choice of material the angle change introduced by the four mirrors furthest away from the plasma will be below 1 degrees.

Place, publisher, year, edition, pages
2004. Vol. 75, 3446-3448 p.
National Category
Atom and Molecular Physics and Optics
Identifiers
URN: urn:nbn:se:kth:diva-6553DOI: 10.1063/1.1779615ISI: 000224755900020Scopus ID: 2-s2.0-9944234666OAI: oai:DiVA.org:kth-6553DiVA: diva2:11298
Note
QC 20100906Available from: 2006-12-11 Created: 2006-12-11 Last updated: 2017-12-14Bibliographically approved
In thesis
1. Diagnostics for advanced fusion plasma scenarios
Open this publication in new window or tab >>Diagnostics for advanced fusion plasma scenarios
2006 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

Over the past decade, fusion research has showed the potential of being a main candidate for energy production for future generations. Further advances in improved fusion performance are therefore vital. This thesis focuses on advanced fusion plasma scenarios and their diagnostic requirements. In particular the design of a motional Stark effect (MSE) diagnostic at the MAST spherical tokamak and the analysis of magneto-hydrodynamic mode feedback control and pulsed poloidal current drive (PPCD) at the reversed field pinch (RFP) experiment EXTRAP T2R are discussed.

The MSE diagnostic is important for the determination of the plasma current profile, information that is necessary for studies in advanced confinement scenarios like reversed shear profiles or current holes. The MAST MSE system has two channels and selects the spectral components using 1Å FWHM interference filters. The diagnostic has been commissioned during the fall of 2006 and the results show the feasibility of the technique with rms-noise ~0.5° using a time resolution of 1 ms. Investigations of mirror labyrinths for the future ITER MSE diagnostic highlight the need for careful calibration considerations.

Feedback control and PPCD are techniques for improved confinement. Feedback control dramatically decreases impurity influx at the end of discharges while transport in the bulk plasma is largely unaffected. During PPCD the transport is seen to decrease and it is demonstrated that PPCD and feedback control can be employed simultaneously.

New and innovative techniques for fusion spectroscopy are furthermore described. This includes the use of correlations in line integrated signals to determine ion emission profiles in poloidally symmetric environments. Good agreement with other diagnostic methods is obtained. The assessment of electron temperature profiles using measured differences between Thomson scattering and vacuum ultra-violet spectroscopy is also shown.

Place, publisher, year, edition, pages
Stockholm: KTH, 2006. xiv, 84 p.
Series
Trita-FYS, ISSN 0280-316X ; 2006:64
Keyword
MSE, PEM, mirror evolution, fusion, diagnostics, plasma spectroscopy, reversed field pinch, spherical tokamak, intelligent shell, PPCD, MAST, ITER
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-4221 (URN)91-7178-474-8 (ISBN)
Public defence
2006-12-15, Sal F3, KTH, Lindstedtsvägen 26, Stockholm, 09:00
Opponent
Supervisors
Note
QC 20100907Available from: 2006-12-11 Created: 2006-12-11 Last updated: 2010-09-07Bibliographically approved
2. Radial profiling using local and line integrated spectroscopic measurements
Open this publication in new window or tab >>Radial profiling using local and line integrated spectroscopic measurements
2005 (English)Licentiate thesis, comprehensive summary (Other scientific)
Place, publisher, year, edition, pages
Stockholm: KTH, 2005. xiv, 34 p.
Series
Trita-FYS, ISSN 0280-316X ; 2005:25
Keyword
Atomic and molecular physics, Atom- och molekylfysik
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-346 (URN)91-7178-047-5 (ISBN)
Presentation
2005-05-20, Sal FB51, AlbaNova, Roslagstullbacken 21, Stockholm, 10:00
Supervisors
Note
QC 20101207Available from: 2005-08-01 Created: 2005-08-01 Last updated: 2010-12-07Bibliographically approved

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Rachlew, Elisabeth

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