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
Liquid-Jet-Target Microfocus X-Ray Sources: Electron Guns, Optics and Phase-Contrast Imaging
KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
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 [en]
electron-impact, x-ray, brightness, liquid-jet-target, phase-contrast imaging
National Category
Other Engineering and Technologies
Identifiers
URN: urn:nbn:se:kth:diva-4802ISBN: 978-91-7415-004-9 (print)OAI: oai:DiVA.org:kth-4802DiVA: diva2:14049
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
List of papers
1. High-intensity electron beam for liquid-metal-jet anode hard x-ray generation
Open this publication in new window or tab >>High-intensity electron beam for liquid-metal-jet anode hard x-ray generation
2005 (English)In: Proceedings of SPIE, the International Society for Optical Engineering, ISSN 0277-786X, E-ISSN 1996-756X, Vol. 5918Article in journal (Refereed) Published
Abstract [en]

We report on our progress towards the experimental realization of a liquid-metal-jet-anode x-ray source with high brightness. We have previously shown that this electron-impact source has potential for very high x-ray brightness by combining small-spot high-flux operation of the electron beam with high-speed operation of the regenerative liquid-metal-jet anode. In the present paper we review the system and describe theoretical calculations for improving the 50 kV, 600 W electron-beam focussing to ∼30 μm spot size. With such a system the power density on the liquid-metal-jet would be ∼400 kW/mm 2, i.e., more than an order of magnitude higher than the power density on a state-of-the-art rotating anode.

Keyword
Electron impact, High brightness, Liquid-jet, Liquid-metal anode, Source, X-ray, X-ray imaging
National Category
Other Engineering and Technologies
Identifiers
urn:nbn:se:kth:diva-8662 (URN)10.1117/12.616480 (DOI)2-s2.0-30844443714 (Scopus ID)
Note
QC 20100915Available from: 2008-06-04 Created: 2008-06-04 Last updated: 2017-12-14Bibliographically approved
2. Microscopic High-Speed Liquid-Metal Jets in Vacuum
Open this publication in new window or tab >>Microscopic High-Speed Liquid-Metal Jets in Vacuum
2005 (English)In: Experiments in Fluids, ISSN 0723-4864, E-ISSN 1432-1114, Vol. 39, 799-804 p.Article in journal (Refereed) Published
Abstract [en]

We describe a novel electron-impact x-ray source based on a high-speed liquid-metal-jet anode. Thermal power load calculations indicate that this new anode concept potentially could increase the achievable brightness in compact electron-impact x-ray sources by more than a factor 100 compared to current state-of-the-art rotating-anode or microfocus sources. A first, successful, low-power proof-of-principle experiment is described and the feasibility of scaling to high-brightness and high-power operation is discussed. Some possible applications that would benefit from such an increase in brightness are also briefly

Keyword
brightness, X-ray source, electron-impact, liquid-metal jet
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-5836 (URN)10.1007/s00348-005-0013-9 (DOI)000233239900002 ()2-s2.0-27744509715 (Scopus ID)
Note
QC 20100915Available from: 2006-05-30 Created: 2006-05-30 Last updated: 2017-12-14Bibliographically approved
3. Stability and debris in high-brightness liquid-metal-jet-anode microfocus x-ray sources
Open this publication in new window or tab >>Stability and debris in high-brightness liquid-metal-jet-anode microfocus x-ray sources
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.

Keyword
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:nbn:se:kth:diva-8664 (URN)10.1063/1.2423229 (DOI)000243890800173 ()2-s2.0-33847751834 (Scopus ID)
Note
QC 20100915Available from: 2008-06-04 Created: 2008-06-04 Last updated: 2017-12-14Bibliographically approved
4. Phase-contrast x-ray imaging with a liquid-metal-jet-anode microfocus source
Open this publication in new window or tab >>Phase-contrast x-ray imaging with a liquid-metal-jet-anode microfocus source
2007 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 91, no 7, 074104- p.Article in journal (Refereed) Published
Abstract [en]

Phase-contrast methods increase contrast, detail, and selectivity in x-ray imaging. Present compact x-ray sources do not provide the necessary spatial coherence with sufficient power to allow the laboratory-scale high-resolution phase-contrast imaging with adequate exposure times. In this letter, the authors demonstrate phase-contrast imaging with few-micron detail employing a compact similar to 6.5 mu m spot liquid-metal-jet-anode high-brightness microfocus source. The 40 W source is operated at more than ten times higher electron-beam power density than present microfocus sources and is shown to provide sufficient spatial coherence as well as scalability to high power, thereby enabling the application of phase-contrast x-ray imaging with short exposure times in clinics and laboratories.

Keyword
Coherent light, Electron beams, Luminance, Optical resolving power, Electron-beam power density, Phase-contrast x-ray imaging, Spatial coherence
National Category
Other Engineering and Technologies
Identifiers
urn:nbn:se:kth:diva-8665 (URN)10.1063/1.2769760 (DOI)000248866600120 ()2-s2.0-34548008161 (Scopus ID)
Note
QC 20100915Available from: 2008-06-04 Created: 2008-06-04 Last updated: 2017-12-14Bibliographically approved
5. A 9 keV electron-impact liquid-gallium-jet x-ray source
Open this publication in new window or tab >>A 9 keV electron-impact liquid-gallium-jet x-ray source
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.

Keyword
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:nbn:se:kth:diva-8666 (URN)10.1063/1.2833838 (DOI)000252821800060 ()2-s2.0-38849143134 (Scopus ID)
Note
QC 20100915Available from: 2008-06-04 Created: 2008-06-04 Last updated: 2017-12-14Bibliographically approved
6. A microfocus x-ray source based on a nonmetal liquid-jet anode
Open this publication in new window or tab >>A microfocus x-ray source based on a nonmetal liquid-jet anode
Show others...
2008 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 92, no 23, 233509-1-233509-3 p.Article in journal (Refereed) Published
Abstract [en]

We demonstrate stable operation of a nonmetallic anode in an electron-impact x-ray source. A high-brightness electron beam is focused on a similar to 70 m/s speed, similar to 10 mu m diameter methanol jet producing stable x-ray emission with peak spectral brightness at similar to 5.4 x 10(5) photons/(s x mu m(2) x sr x 0.1% BW). The jet is fully evaporated in the interaction point. The shape of a simulated spectrum using Monte Carlo methods shows good agreement with experimental data, and the theoretical brightness values give an upper limit for the achievable x-ray emission from jets with very high velocities. Using this anode concept, all compounds and elements found in liquid form are potentially usable for x-ray generation.

Keyword
Auger electron spectroscopy, Charged particles, Electron beams, Electron optics, Electron sources, Electrons, Farm buildings, Luminance, Methanol, Optical properties, Particle beams, X ray apparatus, X rays, Electron impact (EI), High-brightness (HB), Liquid jets, microfocus x-ray, Spectral brightness, stable operations, X-ray emissions, x-ray sources
National Category
Other Engineering and Technologies
Identifiers
urn:nbn:se:kth:diva-8667 (URN)10.1063/1.2942379 (DOI)000256706000091 ()2-s2.0-45149105282 (Scopus ID)
Note
QC 20100915. Uppdaterad från submitted till published (20100915).Available from: 2008-06-04 Created: 2008-06-04 Last updated: 2017-12-14Bibliographically approved

Open Access in DiVA

fulltext(5027 kB)6474 downloads
File information
File name FULLTEXT01.pdfFile size 5027 kBChecksum SHA-1
c3e55172af3dfe0d315642bf65c64354800dd39cc0ee6dd2be1144624ec65a5b55a3e9a4
Type fulltextMimetype application/pdf

Search in DiVA

By author/editor
Tuohimaa, Tomi
By organisation
Biomedical and X-ray Physics
Other Engineering and Technologies

Search outside of DiVA

GoogleGoogle Scholar
Total: 6474 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 684 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