Magnetic focusing of microfocus X-Ray tube I've got this Russian X-Ray tube - BS-5. It has specified focus spot size of $\approx 6~\mathrm{\mu m}$.  
It works, but I've seen brief mentions that in order to reach specified $6~\mathrm{\mu m}$ spot size one should use magnetic focusing. Does anyone have any guideline/links on how this magnetic focusing should be applied in principle to the tubes of this shape/type?

 A: Looking around on the internet a bit, I found several resources that may be of interest.


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*A patent, online here, that is for the magnetic focusing of x-ray tubes. It includes a nice description, as well as references and diagrams. According to the description,



A primary object of the invention resides in the provi sion [sic] of an improved method f0. [sic] the reduction of the focal spot size within an X-ray tube which is adapted to deliver an X-ray burst of extremely short time duration.

This seems to be exactly what you are looking for. It also includes a couple of diagrams showing the x-ray tube this system is intended for, and I'm not an expert but it doesn't look too different from what you've got. So that may be of assistance.


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*Another patent, online here, describes a magnetic focusing lens that might be somewhat related to what you are looking at.

*This paper is about electrostatic focusing, not magnetic focusing, but may also be useful in providing other methods to do what you want to do. 

*Finally, this book excerpt may be useful; it goes more in depth on magnetic focusing lenses. 


Hope this helps! I'll be adding more resources as I find them.
