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A microfocus x-ray source based on a nonmetal liquid-jet anode
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.
Facultat de Física (ECM), Universitat de Barcelona.
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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.

Place, publisher, year, edition, pages
2008. Vol. 92, no 23, 233509-1-233509-3 p.
Keyword [en]
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: urn:nbn:se:kth:diva-8667DOI: 10.1063/1.2942379ISI: 000256706000091Scopus ID: 2-s2.0-45149105282OAI: oai:DiVA.org:kth-8667DiVA: diva2:14048
Note
QC 20100915. Uppdaterad från submitted till published (20100915).Available 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

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Hertz, Hans M.Vogt, Ulrich

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