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Title: Low emittance growth in a low energy beam transport line with un-neutralized section

Journal Article · · Physical Review Accelerators and Beams
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In a Low Energy Beam Transport line (LEBT), the emittance growth due to the beam's space charge is typically suppressed by way of neutralization from either electrons or ions, which originate from ionization of the background gas. In cases where the beam is chopped, the neutralization pattern usually changes throughout the beginning of the pulse, causing the Twiss parameters to differ significantly from their steady state values, which, in turn, may result in beam losses downstream. For a modest beam perveance, there is an alternative solution, in which the beam is kept un-neutralized in the portion of the LEBT that contains the chopper. The emittance can be nearly preserved if the transition to the un-neutralized section occurs where the beam exhibits low transverse tails. This report introduces the rationale for the proposed scheme and formulates the physical arguments for it as well as its limitations. In conclusion, an experimental realization of the scheme was carried out at Fermilab's PIP2IT where low beam emittance dilution was demonstrated for a 5 mA, 30 keV $$H^{-}$$ beam.

Research Organization:
Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
Sponsoring Organization:
USDOE Office of Science (SC), High Energy Physics (HEP)
Grant/Contract Number:
AC02-07CH11359
OSTI ID:
1419706
Alternate ID(s):
OSTI ID: 1415629
Report Number(s):
Fermilab-Pub-17-599-AD; arXiv:1805.01920; FERMILAB-PUB-17-599-AD; PRABCJ; 020101
Journal Information:
Physical Review Accelerators and Beams, Journal Name: Physical Review Accelerators and Beams Vol. 21 Journal Issue: 2; ISSN 2469-9888
Publisher:
American Physical SocietyCopyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 3 works
Citation information provided by
Web of Science

References (4)

H− beam neutralization measurements in a solenoidal beam transport system
  • Sherman, Joseph; Pitcher, Eric; Stevens, Ralph
  • Production and neutralization of negative ions and beams, AIP Conference Proceedings https://doi.org/10.1063/1.44814
conference January 1992
Relation between Field Energy and RMS Emittance in Intense Particle Beams journal January 1985
Negative ion beam space charge compensation by residual gas journal August 2015
Generation of initial kinetic distributions for simulation of long-pulse charged particle beams with high space-charge intensity journal November 2009

Figures / Tables (13)

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Figure 10(p. 7)figure Figure 10
Figure 11(p. 8)figure Figure 11
Table 1(p. 8)table Table 1
Figure 12(p. 9)figure Figure 12

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