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A 9 keV electron-impact liquid-gallium-jet x-ray source
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.
KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.ORCID iD: 0000-0002-4394-0591
KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.ORCID iD: 0000-0003-2723-6622
2008 (English)In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 79, no 1, 016102- p.Article in journal (Refereed) Published
Abstract [en]

We demonstrate a high-brightness compact 9 keV electron-impact microfocus x-ray source based on a liquid-gallium-jet anode. A similar to 30 W, 50 kV electron gun is focused onto the similar to 20 m/s, 30 mu m diameter liquid-gallium-jet anode to produce an similar to 10 mu m full width at half maximum x-ray spot. The peak spectral brightness is >2 x 10(10) photons/(s mm(2) mrad(2) x 0.1% BW). Calculation and experiments show potential for increasing this brightness by approximately three orders of magnitude, making the source suitable for laboratory-scale x-ray crystallography and hard x-ray microscopy.

Place, publisher, year, edition, pages
2008. Vol. 79, no 1, 016102- p.
Keyword [en]
Electron guns, Gallium, Luminance, Microscopic examination, Photons, X ray crystallography, Electron impact, Hard x-ray microscopy, Peak spectral brightness, X-ray spot
National Category
Other Engineering and Technologies
Identifiers
URN: urn:nbn:se:kth:diva-8666DOI: 10.1063/1.2833838ISI: 000252821800060Scopus ID: 2-s2.0-38849143134OAI: oai:DiVA.org:kth-8666DiVA: diva2:14047
Note
QC 20100915Available from: 2008-06-04 Created: 2008-06-04 Last updated: 2010-09-15Bibliographically approved
In thesis
1. A Compact High-Brightness Liquid-Metal-Jet X-Ray Source
Open this publication in new window or tab >>A Compact High-Brightness Liquid-Metal-Jet X-Ray Source
2006 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis describes the development and characterization of a compact high-brightness liquid-metal-jet anode x-ray source. Initial calculations show that a source based on this concept could potentially lead to a >100-fold increase of the brightness compared to current state-of-the-art rotating-anode x-ray sources. This improvement is due to an increased thermal load capacity of the anode.

A low-power proof-of-principle source has been built, and experiments show that the liquid-metal-jet anode can be operated at more than an order of magnitude higher power densities than modern solid-metal anodes. This brightness enhancement has been utilized to acquire in-line phase-contrast images of weakly absorbing objects with substantially shorter exposure times than previously reported. To be able to target different application areas different liquid-jet-anode materials have been tested. The Sn-jet anode could potentially be used in mammography examinations, whereas the Ga-jet could be utilized for, e.g., protein-structure determination with x-ray diffraction.

Scaling to higher power and brightness levels is discussed and seems conceivable. A potential obstacle for further development of this source concept, the generation of a microscopic high-speed liquid-metal jet in vacuum, is investigated and is proven to be feasible. Dynamic-similarity experiments using water jets to simulate 30-μm, ~500-m/s tin and gallium jets show good coherence and directional stability of the jet. Other potential difficulties in the further source development, such as excessive debris emission and instabilities of the x-ray emission spot, are also investigated in some detail.

Place, publisher, year, edition, pages
Stockholm: KTH, 2006. xii, 61 p.
Series
Trita-FYS, ISSN 0280-316X ; 2006:36
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-4005 (URN)91-7178-371-7 (ISBN)
Public defence
2006-06-09, Sal D3, Lindstedtsvägen 5, Stockholm, 10:00 (English)
Opponent
Supervisors
Note
QC 20100915Available from: 2006-05-30 Created: 2006-05-30 Last updated: 2010-09-15Bibliographically approved
2. Liquid-Jet-Target Microfocus X-Ray Sources: Electron Guns, Optics and Phase-Contrast Imaging
Open this publication in new window or tab >>Liquid-Jet-Target Microfocus X-Ray Sources: Electron Guns, Optics and Phase-Contrast Imaging
2008 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This Thesis describes the development of an electron-impact microfocus x-ray source and its application for phase-contrast imaging. The source is based on a novel, liquid-jet target concept. Stable and continuous operation can be achieved at substantially higher electron-beam power densities than conventional solid target based systems. The maximum x-ray brightness can potentially be increased by a factor of 10-1000, which would provide significantly improved performance in applications such as imaging. In order to reach the high x-ray brightness, comparable performance from the electron gun is needed. A LaB6-cathode-based electron gun is analyzed in terms of achievable e-beam brightness and beam quality and is found capable to deliver power densities in the 10-100 MW/mm2 range using optimized electro-optics. A proof-of-principle microfocus source has been developed. Experiments show that the liquid-metal-jet target can be operated at more than an order of magnitude higher e-beam power densities than modern solid-metal targets. This brightness enhancement has been utilized to acquire in-line phase-contrast images of weakly absorbing objects. The source potentially enables the application of high-resolution phase-contrast x-ray imaging with short exposure times in clinics and laboratories.

Different liquid-jet-target materials have been tested. The Sn-jet (Ka=25.3 keV) could be suitable for mammography, whereas the Ga-jet ((Ka=9.2 keV) may be utilized for x-ray diffraction studies. In addition, a non-metallic methanol jet has been the demonstrated in stable x-ray operation. All materials and compounds found in liquid form can, thus, potentially be used for electron-impact liquid-jet-target x-ray generation.

Scaling to higher e-beam power density and x-ray brightness levels is discussed and is determined to be feasible. Potential difficulties, such as debris emission and instabilities of the x-ray emission spot, are investigated in some detail. Larger and/or faster jets could overcome the present limitations because of their inherently higher heat load capacities. Dynamic-similarity experiments show that liquid jets can in principle be operated in a stable manner at much higher speeds than previously shown.

Place, publisher, year, edition, pages
Stockholm: KTH, 2008. x, 91 p.
Series
Trita-FYS, ISSN 0280-316X ; 2008:12
Keyword
electron-impact, x-ray, brightness, liquid-jet-target, phase-contrast imaging
National Category
Other Engineering and Technologies
Identifiers
urn:nbn:se:kth:diva-4802 (URN)978-91-7415-004-9 (ISBN)
Public defence
2008-06-13, FR4, Albanova, Roslagstullsbacken 21, Stockholm, 14:00 (English)
Opponent
Supervisors
Note
QC 20100915Available from: 2008-06-04 Created: 2008-06-04 Last updated: 2010-09-15Bibliographically approved

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Vogt, UlrichHertz, Hans M.

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