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Development of visible spectroscopic techniques for applications in plasma diagnostics
KTH, School of Engineering Sciences (SCI), Physics.
2006 (English)Licentiate thesis, comprehensive summary (Other scientific)
Abstract [en]

In this thesis visible spectroscopy is developed and used for two applications.

Studies of motional Stark effect spectra for diagnosing the current distribution in the fusion plasmas with two different spectroscopic diagnostic systems: ratiometry and interferometry. Both systems provide non-invasive method for diagnosis of the internal plasma properties, e.g. magnetic field. Pitch angle of magnetic field lines are obtained from polarisation of Stark split Hα spectral lines emitted by energetic hydrogen atoms injected into the plasma volume by neutral beam. Several methods of calibration of the systems on TEXTOR and JET are discussed. The main result of this work is the first measurement of the safety factor radial profile with new ratiometric MSE system on TEXTOR.

Studies of molecular fragmentation of free molecules CH4 and NH3 excited with synchrotron radiation by detection of the fluorescence from the fragments. The results give the decay path ways for the molecules when excited below the N and C ionisation edges.

Place, publisher, year, edition, pages
Stockholm: KTH , 2006. , xi, 39 p.
Series
Trita-FYS, ISSN 0280-316X ; 2006:66
National Category
Physical Sciences
Identifiers
URN: urn:nbn:se:kth:diva-4252ISBN: 91-7178-479-9 (print)OAI: oai:DiVA.org:kth-4252DiVA: diva2:11470
Presentation
2006-12-12, FA31, AlbaNova univ. centrum, Roslagstullsgatan 21, Stockholm, 10:00
Opponent
Supervisors
Note
QC 20101116Available from: 2006-12-22 Created: 2006-12-22 Last updated: 2010-11-17Bibliographically approved
List of papers
1. Motional Stark Effect Diagnostic on TEXTOR
Open this publication in new window or tab >>Motional Stark Effect Diagnostic on TEXTOR
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2004 (English)In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 75, no 10, 3475-3477 p.Article in journal (Refereed) Published
Abstract [en]

A motional Stark effect diagnostic at the tokamak TEXTOR has been constructed and brought recently into operation. In contrast to diagnostics used on other tokamaks, this diagnostic reveals the direction of the magnetic field from the intensity ratio of the pi and sigma components of the emitted Balmer-alpha and not from a polarization measurement of a single line. Moreover, the complete spectrum is measured which allows determining the radial position of the measurement, and in principle the radial electric field.

Keyword
Approximation theory, Cameras, Charge coupled devices, Computational geometry, Doppler effect, Electric fields, Electron emission, Light polarization, Sensitivity analysis
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-6688 (URN)10.1063/1.1784535 (DOI)000224755900029 ()
Note
QC 20101116Available from: 2006-12-22 Created: 2006-12-22 Last updated: 2017-12-14Bibliographically approved
2. Overview of core diagnostics for TEXTOR
Open this publication in new window or tab >>Overview of core diagnostics for TEXTOR
2005 (English)In: Fusion science and technology, ISSN 1536-1055, E-ISSN 1943-7641, Vol. 47, no 2, 220-245 p.Article in journal (Refereed) Published
Abstract [en]

The diagnostic system of TEXTOR comprises about 50 individual diagnostic devices. Since the start of the Trilateral Euregio Cluster collaboration, part of the emphasis in the experimental program has shifted toward the study of physics processes in the plasma core. To aid these studies several new and advanced core diagnostics have been implemented, whereas a number of other core diagnostics have been upgraded to higher resolution, more channels, and better accuracy. In this paper a brief overview is given of the present set of plasma core diagnostics at TEXTOR.

Keyword
TEXTOR, diagnostics, core diagnostics
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-6689 (URN)000226876100017 ()
Note
QC 20101116Available from: 2006-12-22 Created: 2006-12-22 Last updated: 2017-12-14Bibliographically approved
3. Lyman and Balmer emission following core excitations in methane and ammonia molecules
Open this publication in new window or tab >>Lyman and Balmer emission following core excitations in methane and ammonia molecules
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2007 (English)In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 40, no 8, 1489-1500 p.Article in journal (Refereed) Published
Abstract [en]

The intensities of hydrogen Lyman-alpha and Balmer series emission lines as a result of photoexcitation of free CH4 and NH3 molecules at the C 1s and N 1s edges have been measured. For methane, the total fluorescence yield in the visible region ( 300 - 650 nm) was also recorded. Excitation functions of the Balmer lines show relative intensity enhancement of Balmer-beta emission in comparison with Balmer-alpha at higher core- to- Rydberg excitations. The Lyman-alpha emission intensity, in general, follows the relations observed in the corresponding total ion yield measurements. Additionally, the Balmer-gamma and -delta yields were measured for ammonia molecules and they show intensity maxima at photon energies shifted closer to the N 1s threshold than Balmer-alpha and -beta. A quantum defect analysis is performed to find out which core excitations are responsible for this enhanced intensity. Dissociation pathways leading to the emission in H atoms are discussed.

Keyword
Ammonia, Dissociation, Fluorescence, Methane, Photons, Rydberg states, Balmer series emission lines, Core excitations, Photon energies, Quantum defect analysis, Rydberg excitations
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-7999 (URN)10.1088/0953-4075/40/8/003 (DOI)000246010300004 ()2-s2.0-34247098021 (Scopus ID)
Note
QC 20100916Available from: 2008-02-20 Created: 2008-02-20 Last updated: 2017-12-14Bibliographically approved

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