Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Stability and debris in high-brightness liquid-metal-jet-anode microfocus x-ray sources
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: 0000-0003-2723-6622
2007 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 101, no 2, 026102- p.Article in journal (Refereed) Published
Abstract [en]

We investigate the x-ray spot stability and the debris emission in liquid-metal-jet anode electron-impact x-ray sources operating in the 10-100 W microfocus regime. The x-ray spot size is 15-23 mu m in diameter and the electron-beam power density is up to similar to 210 kW/mm(2), an order of magnitude higher than for conventional microfocus sources. In the power range of the investigation the source is stable in terms of spot size and position. The debris emission rate increases exponentially with the applied electron-beam power but may be reduced by combining larger and faster target jets with smaller e-beam foci and by mitigation schemes. It is concluded that the investigated factors will not limit the performance and function of liquid-metal-jet-anode electron-impact microfocus sources when operating in this high-brightness regime.

Place, publisher, year, edition, pages
2007. Vol. 101, no 2, 026102- p.
Keyword [en]
Anodes, Electron beams, Light emission, Liquid metals, Debris emission, e-beam foci, Electron-impact, Microfocus x-ray sources
National Category
Other Engineering and Technologies
Identifiers
URN: urn:nbn:se:kth:diva-8664DOI: 10.1063/1.2423229ISI: 000243890800173Scopus ID: 2-s2.0-33847751834OAI: oai:DiVA.org:kth-8664DiVA: diva2:14045
Note
QC 20100915Available from: 2008-06-04 Created: 2008-06-04 Last updated: 2017-12-14Bibliographically approved
In thesis
1. 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
2. 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

Open Access in DiVA

No full text

Other links

Publisher's full textScopus

Authority records BETA

Hertz, Hans M.

Search in DiVA

By author/editor
Otendal, MikaelTuohimaa, TomiHertz, Hans M.
By organisation
Biomedical and X-ray Physics
In the same journal
Journal of Applied Physics
Other Engineering and Technologies

Search outside of DiVA

GoogleGoogle Scholar

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 83 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf