A Compact High-Brightness Liquid-Metal-Jet X-Ray Source

• Main Author: Otendal, Mikael
• Format: Doctoral Thesis
• Language: English
• Published: KTH, Biomedicinsk fysik och röntgenfysik 2006
• Subjects: Physics; Fysik
• Online Access: http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4005; http://nbn-resolving.de/urn:isbn:91-7178-371-7

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. === QC 20100915