Focal spot size predictions for beam transport through a gas-filled reactor Page: 7 of 12
This article is part of the collection entitled: Office of Scientific & Technical Information Technical Reports and was provided to Digital Library by the UNT Libraries Government Documents Department.
The following text was automatically extracted from the image on this page using optical character recognition software:
in two ways. First, when particles at different radial positions of a given
bean segment experience different focusing forces (due to aaharaonic pinch
fields), there is a net increase in the emittance of that disc, which leads
in turn to an enlarged neck radius. Secondly, the average pinch force
experienced by various beam segments are different. The resulting variable
focal lengths imply that as the beam impinges upon a target placed at any
point in the reactor, most of the beam discs will be slightly out of focus.
For the converging beam, it is possible to derive an approximate
solution for the neck radius of a beam segment from Eq. (1). it :s given by
whero the final emittance is the initial enittance enhanced by multiple
scattering and. self-field effects
Ef = E0 +
The geometric factor (a /R ) in Eq. (2) determines the amount of
emittance growth that can be tolerated to achieves given neck radius. The
parameter 8 represents a correction due to gross pinching effects, given by
Emittance increase due to multiple scattering is well known, and is
0 .... n R
scatt g w
where is the gas density, and the factor of 1/3 resultB from the
converging beam geometry. <j t is an effective cross section for
multiple acattering, given by
„ 8, .* Zi Z-
1 scatt "777 r
where Z. and 2 are the atomic number of the heavy ion and the gas,
respectively, and H is the mass of the ion. ZnT provides the cutoff in
Here’s what’s next.
This article can be searched. Note: Results may vary based on the legibility of text within the document.
Tools / Downloads
Get a copy of this page or view the extracted text.
Citing and Sharing
Basic information for referencing this web page. We also provide extended guidance on usage rights, references, copying or embedding.
Reference the current page of this Article.
Yu, S.S.; Lee, E.P. & Buchanan, H.L. Focal spot size predictions for beam transport through a gas-filled reactor, article, January 23, 1980; Livermore, California. (https://digital.library.unt.edu/ark:/67531/metadc1087464/m1/7/: accessed March 26, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.