• Open Access

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

L. Prost, J.-P. Carneiro, and A. Shemyakin
Phys. Rev. Accel. Beams 21, 020101 – Published 6 February 2018

Abstract

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. 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.

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  • Received 26 July 2017

DOI:https://doi.org/10.1103/PhysRevAccelBeams.21.020101

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.

Published by the American Physical Society

Physics Subject Headings (PhySH)

Accelerators & Beams

Authors & Affiliations

L. Prost*, J.-P. Carneiro, and A. Shemyakin

  • Fermi National Accelerator Laboratory, Batavia, Illinois 60510, USA

  • *lprost@fnal.gov

Article Text

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Issue

Vol. 21, Iss. 2 — February 2018

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