Scheme to funnel ion beams with a radio-frequency quadrupole Page: 2 of 17
This article is part of the collection entitled: Office of Scientific & Technical Information Technical Reports and was provided to UNT Digital Library by the UNT Libraries Government Documents Department.
Extracted Text
The following text was automatically extracted from the image on this page using optical character recognition software:
SCHEME TO FUNNEL ION BEAMS
WITH A RADIO-FREQUENCY QUADRUPOLE*
R. H. Stokes and G. N. Mlnerbo.t MS H817
Los Alamos National Laboratory, Los Alamos, NM 87545
ABSTRACT
We describe a proposed method to funnel 1on beams using a new
form of the radio-frequency quadrupole (RFQ) structure. This RFQ
accepts two bunched 1on beams and combines them Into a single final
beam with Interlaced microstructure pulses. It also provides
uninterrupted periodic transverse focusing to facilitate the
funnellng of beams with high current and low emlttance.
INTRODUCTION
Several new linear-accelerator applications require output 1on
beams with very high current and small transverse emlttance. The
transverse beam brightness (beam current divided by the product of
the x- and y-em1ttances) 1s often used as the figure of merit, and
the design objective 1s to obtain a very high brightness output
beam. When linear-accelerator channels operate near their
space-charge limit, one method to Increase brightness 1s to combine
the beams from two (or more) space-charge-Umlted channels. The
resultant beam would have Interlaced microstructure bunches and
would be suitable for further acceleration in ; Unac operating
with twice the frequency. This operation has been called funnellng
and was first proposed as a necessary part of the rf Unac approach
to heavy-1on fusion.1 If the funnellng of two beams 1s
accomplished with no transverse emlttance growth or beam loss, the
resulting beam will have twice the current and twice the brightness
of the beams that are combined. Increasing beam brightness through
funnellng requires no Improvement 1n the Ion source or accelerator
techniques used before the funnellng process.
In some applications, to meet brightness requirements, one
could use arrays having mu Mple beams traversing the whole
accelerator system with the final beams all focused to a common
target spot. If the required brightness were not too high,
funnellng to combine multiple beams as early as possible would be
especially advantageous 1i large accelerators where most of the
acceleration could then be provided 1n a minimum-cost single-beam
accelerator. In general this single-beam accelerator would he less
complex and would require less rf power than designs that carry all
the Initial beams through the entire accelerator system. A
funnellng tree to combine four beams 1s shown 1n F1g. 1. Ir
practice, funnellng to Increase beam brightness li a difficult
"'Work supported by the US Department of Energy.
+Now with Schlumberger, Houston Engineering Center.
Upcoming Pages
Here’s what’s next.
Search Inside
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.
Stokes, R.H. & Minerbo, G.N. Scheme to funnel ion beams with a radio-frequency quadrupole, article, January 1, 1985; New Mexico. (https://digital.library.unt.edu/ark:/67531/metadc1069967/m1/2/: accessed April 25, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.