Low emittance growth in a low energy beam transport line with un-neutralized section
| Autor: | Lionel Prost, Alexander Shemyakin, Jean-Paul Carneiro |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
Physics
Nuclear and High Energy Physics Physics and Astronomy (miscellaneous) 010308 nuclear & particles physics Particle accelerator Surfaces and Interfaces Electron 01 natural sciences Space charge law.invention law Ionization 0103 physical sciences lcsh:QC770-798 Physics::Accelerator Physics lcsh:Nuclear and particle physics. Atomic energy. Radioactivity Thermal emittance Beam emittance Atomic physics 010306 general physics Beam (structure) Perveance |
| Zdroj: | Physical Review Accelerators and Beams, Vol 21, Iss 2, p 020101 (2018) |
| ISSN: | 2469-9888 |
| Popis: | 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 ${\mathrm{H}}^{\ensuremath{-}}$ beam. |
| Databáze: | OpenAIRE |
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