Mikhail Taubin, Presenter: Nothing to Disclose

Serguei Alekseev, Abstract Co-Author: Nothing to Disclose

Anton Yaskolko, Abstract Co-Author: Nothing to Disclose

Dmitry Shestikh, Abstract Co-Author: Nothing to Disclose

Andrey Pavlov, Abstract Co-Author: Nothing to Disclose

The authors think that this effect results from forming nanoscale little bubbles filled with potassium at the grain boundaries ( Fig.3). Results of forming CNT on single crystal tungsten base (without catalyst) are introduce.Fig.4. Schemes of miniature X-Ray sources with thermal emission and field cathode are represent. (Fig.5).

Results of development and creation of nanocompozites of refractory metals with increased strength characteristics for anodes and and emissive parameters cathodes are analyzed in this report. 

This effect is explained by the fact that when forming nanomaterials current tubes with decreased work function arise close to grain boundaries in the region 10 nm wide. This effect is able to increase the intensity of X-radiation considerably (by a factor of more than 5) at the same cathode temperatures or decrease the temperature of a cathode by 400oC at the same intensity of X-radiation. The authors carried out some experiments to determine the creep of tungsten alloying by potassium on samples as foils 100 m thick, used when manufacturing X-ray tube cathodes. The results of these experiments showed that high-temperature sample annealing resulted in a sharp increase (by a factor of more than 3) in material creep resistance at a temperature of 2200oC.

It is shown, that though monocrystals have shown the better characteristics in comparison with traditional polycrystals both as anodes and as cathodes, more radical way of increase of operational characteristics of the miniature x-ray tubes is in application of the refractory nanostructural materials. Application of nanocrystal and monocrystals materials have to increase allowable unit loads of a miniature X-ray tube by reducing porosity, increasing strength and plasticity of anode and cathode materials. Some results of investigations in which the work function of nanocrystal tungsten is lower by 0.8 eV than that of polycrystals tungsten are given.( Fig.1)

Taubin, M, Alekseev, S, Yaskolko, A, Shestikh, D, Pavlov, A, Miniature X-ray Sources Produced from Nano and Monocrystal Materials.  Radiological Society of North America 2012 Scientific Assembly and Annual Meeting, November 25 - November 30, 2012 ,Chicago IL. http://archive.rsna.org/2012/12024539.html