skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Characteristics of the fourth order resonance in high intensity linear accelerators

Abstract

For the 4σ = 360° space-charge resonance in high intensity linear accelerators, the emittance growth is surveyed for input Gaussian beams, as a function of the depressed phase advance per cell σ and the initial tune depression (σ o – σ). For each data point, the linac lattice is designed such that the fourth order resonance dominates over the envelope instability. Additionally, the data show that the maximum emittance growth takes place at σ ≈ 87° over a wide range of the tune depression (or beam current), which confirms that the relevant parameter for the emittance growth is σ and that for the bandwidth is σ o – σ. An interesting four-fold phase space structure is observed that cannot be explained with the fourth order resonance terms alone. Analysis attributes this effect to a small negative sixth order detuning term as the beam is redistributed by the resonance. Analytical studies show that the tune increases monotonically for the Gaussian beam which prevents the resonance for σ > 90°. Lastly, frequency analysis indicates that the four-fold structure observed for input Kapchinskij-Vladmirskij beams when σ < 90°, is not the fourth order resonance but a fourth order envelope instability because the 1/4more » = 90°/360° component is missing in the frequency spectrum.« less

Authors:
ORCiD logo [1];  [2]
  1. Institute for Basic Science, Daejeon (South Korea)
  2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1436155
Alternate Identifier(s):
OSTI ID: 1364184
Grant/Contract Number:
AC02-05CH11231
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 24; Journal Issue: 6; Journal ID: ISSN 1070-664X
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS

Citation Formats

Jeon, D., and Hwang, Kyung Ryun. Characteristics of the fourth order resonance in high intensity linear accelerators. United States: N. p., 2017. Web. doi:10.1063/1.4985685.
Jeon, D., & Hwang, Kyung Ryun. Characteristics of the fourth order resonance in high intensity linear accelerators. United States. doi:10.1063/1.4985685.
Jeon, D., and Hwang, Kyung Ryun. Mon . "Characteristics of the fourth order resonance in high intensity linear accelerators". United States. doi:10.1063/1.4985685.
@article{osti_1436155,
title = {Characteristics of the fourth order resonance in high intensity linear accelerators},
author = {Jeon, D. and Hwang, Kyung Ryun},
abstractNote = {For the 4σ = 360° space-charge resonance in high intensity linear accelerators, the emittance growth is surveyed for input Gaussian beams, as a function of the depressed phase advance per cell σ and the initial tune depression (σo – σ). For each data point, the linac lattice is designed such that the fourth order resonance dominates over the envelope instability. Additionally, the data show that the maximum emittance growth takes place at σ ≈ 87° over a wide range of the tune depression (or beam current), which confirms that the relevant parameter for the emittance growth is σ and that for the bandwidth is σo – σ. An interesting four-fold phase space structure is observed that cannot be explained with the fourth order resonance terms alone. Analysis attributes this effect to a small negative sixth order detuning term as the beam is redistributed by the resonance. Analytical studies show that the tune increases monotonically for the Gaussian beam which prevents the resonance for σ > 90°. Lastly, frequency analysis indicates that the four-fold structure observed for input Kapchinskij-Vladmirskij beams when σ < 90°, is not the fourth order resonance but a fourth order envelope instability because the 1/4 = 90°/360° component is missing in the frequency spectrum.},
doi = {10.1063/1.4985685},
journal = {Physics of Plasmas},
number = 6,
volume = 24,
place = {United States},
year = {Mon Jun 19 00:00:00 EDT 2017},
month = {Mon Jun 19 00:00:00 EDT 2017}
}

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on June 19, 2018
Publisher's Version of Record

Save / Share: