Tables for
Volume H
Powder diffraction
Edited by C. J. Gilmore, J. A. Kaduk and H. Schenk

International Tables for Crystallography (2018). Vol. H, ch. 2.1, p. 39

Section Performance of X-ray sources

A. Kerna*

aBruker AXS, Östliche Rheinbrückenstrasse 49, Karlsruhe 76187, Germany
Correspondence e-mail: Performance of X-ray sources

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The single most important property of an X-ray source is its brilliance, which is proportional to the maximum target loading per unit area of the focal spot, also referred to as the specific loading.

In Table 2.1.4[link] the maximum target loading and specific loading (relative brilliance) for some typical sealed tubes and some rotating-anode sources with a Cu target are compared. Also listed are data for the liquid-metal jet with Ga as a target. Micro-focus fixed-target X-ray sources have up to two orders of magnitude higher specific loadings compared to conventional fixed target tubes, and even 2 to 5 times higher specific loadings compared to conventional rotating-anode systems. In contrast to fixed-target micro-focus X-ray sources, where the specific loading can only be increased by reducing the source size, moving-target X-ray sources are also made brighter by increasing the speed of the target relative to the electron beam. Moving-target X-ray sources are thus inherently brighter than stationary targets. The liquid-gallium jet has a higher (by a further order of magnitude) specific loading than the most brilliant rotating-anode systems, and now rivals the intensity of second-generation synchrotron beamlines.

Table 2.1.4| top | pdf |
Maximum target loading and specific loading for some selected fixed- and moving-target X-ray sources

X-ray sourceFocal spot (mm2)Maximum load (kW)Specific loading (kW mm−2)
Fixed target
Broad focus (Cu) 2 × 10 3 0.15
Normal focus (Cu) 1 × 10 2.5 0.25
Long fine focus (Cu) 0.4 × 12 2.2 0.5
Micro-focus (Cu) 0.01–0.05 <0.05 5–50
Moving target
Rotating anode (Cu) 0.5 × 10 18 3.6
  0.3 × 3 5.4 6
  0.2 × 2 3 7.5
  0.1 × 1 1.2 12
Micro-focus rotating anode (Cu) 0.1 2.7 27
Liquid-metal jet (Ga) 0.02 × 0.02 0.2 >500

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