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Stability of liquid-nitrogen-jet laser-plasma targets
KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.ORCID iD: 0000-0002-3717-7307
KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.ORCID iD: 0000-0001-8604-735X
KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.ORCID iD: 0000-0003-2723-6622
2015 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 118, no 17, 174902Article in journal (Refereed) PublishedText
Abstract [en]

Microscopic jets of cryogenic substances such as liquid nitrogen are important regenerative high-density targets for high-repetition rate, high-brightness laser-plasma soft x-ray sources. When operated in vacuum such liquid jets exhibit several non-classical instabilities that negatively influence the x-ray source's spatial and temporal stability, yield, and brightness, parameters that all are important for applications such as water-window microscopy. In the present paper, we investigate liquid-nitrogen jets with a flash-illumination imaging system that allows for a quantitative stability analysis with high spatial and temporal resolution. Direct and indirect consequences of evaporation are identified as the key reasons for the observed instabilities. Operating the jets in an approximately 100 mbar ambient atmosphere counteracts the effects of evaporation and produces highly stable liquid nitrogen jets. For operation in vacuum, which is necessary for the laser plasmas, we improve the stability by introducing an external radiative heating element. The method significantly extends the distance from the nozzle that can be used for liquid-jet laser plasmas, which is of importance for high-average-power applications. Finally, we show that laser-plasma operation with the heating-element-stabilized jet shows improved short-term and long-term temporal stability in its water-window x-ray emission.

Place, publisher, year, edition, pages
American Institute of Physics (AIP), 2015. Vol. 118, no 17, 174902
Keyword [en]
Electric heating elements, Electron sources, Evaporation, Fighter aircraft, Image resolution, Jets, Laser beams, Laser produced plasmas, Liquid nitrogen, Liquids, Luminance, Nitrogen, Nitrogen plasma, Plasma stability, Stability, Vacuum applications, X ray apparatus, X ray optics, Ambient atmosphere, High average power, High brightness lasers, High repetition rate, Quantitative stability analysis, Radiative heating, Spatial and temporal resolutions, Temporal stability, Plasma interactions
National Category
Physical Sciences
URN: urn:nbn:se:kth:diva-181201DOI: 10.1063/1.4935143ISI: 000364584200024ScopusID: 2-s2.0-84946811961OAI: diva2:901018
Swedish Research Council

QC 20160205

Available from: 2016-02-05 Created: 2016-01-29 Last updated: 2016-05-30Bibliographically approved
In thesis
1. 3D X-ray microscopy: image formation, tomography and instrumentation
Open this publication in new window or tab >>3D X-ray microscopy: image formation, tomography and instrumentation
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Tomography in soft X-ray microscopy is an emerging technique for obtaining quantitative 3D structural information about cells. One of its strengths, compared with other techniques, is that it can image intact cells in their near-native state at a few 10 nm’s resolution, without staining. However, the methods for reconstructing 3D-data rely on algorithms that assume projection data, which the images are generally not due to the imaging systems’ limited depth of focus. To bring out the full potential of tomography in soft X-ray microscopy an improved understanding of the image formation is desired.

This Thesis reviews zone plate-based X-ray microscopy for biological imaging and the theory necessary for a numerical implementation of a 3D image formation model. Furthermore, a novel reconstruction approach is proposed that improves the overall resolution in a reconstruction of a tomographically imaged object. This is demonstrated by simulations and experiments. Finally, this Thesis covers work on the Stockholm X-ray microscope, including an upgrade of the X-ray source yielding unprecedented brightness for a compact system. With this upgrade it was possible to do high-quality imaging of cells in their near-native state with only 10 second exposures.

Abstract [sv]

Tomografi i mjukröntgenmikroskopi är en ny teknik för att få ut kvantitativ strukturell 3D information om celler. Dess styrka jämfört med andra tekniker är att den kan avbilda intakta celler i deras nära naturliga tillstånd med ett par 10 nm upplösning, utan omfattande preparering. Dock är metoderna för att rekonstruera 3D-data beroende av algoritmer som antar projektionsdata, vilket bilderna i allmänhet inte är på grund av avbildningsystemens begränsade skärpedjup. För att få ut den fulla potentialen av tomografi i röntgenmikroskopi behövs en ökad förståelse för avbildningsprocessen.

Denna avhandling behandlar zonplatte-baserad röntgenmikroskopi för biologisk avbildning och den nödvändiga teorin för en numerisk implementering av en avbildningsmodell i 3D. En ny rekonstruktionsmetod föreslås som förbättrar upplösningen i rekonstruktionen för ett tomografiskt avbildat objekt. Detta visas i simuleringar och experiment. Slutligen omfattar denna avhandling arbete på Stockholms mjukröntgenmikroskop, inklusive en uppgradering av röntgenkällan som ger oöverträffad ljusstyrka för ett kompakt system. Denna uppgradering möjliggör högkvalitativ avbildning av celler i deras nästan naturliga tillstånd med endast 10 sekunders exponering.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2016. viii, 75 p.
TRITA-FYS, ISSN 0280-316X ; 2016:15
X-ray microscopy, image formation theory, partial coherence in imaging, wave propagation, tomography, instrumentation
National Category
Physical Sciences
Research subject
urn:nbn:se:kth:diva-184095 (URN)978-91-7595-914-6 (ISBN)
Public defence
2016-04-22, FD5, Albanova universitetscentrum, Roslagstullsbacken 21, Stockholm, 13:00 (English)
Swedish Research CouncilKnut and Alice Wallenberg Foundation

QC 20160324

Available from: 2016-03-24 Created: 2016-03-23 Last updated: 2016-03-24Bibliographically approved

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Fogelqvist, EmelieKördel, MikaelSelin, MårtenHertz, Hans M.
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