Characteristics of the fourth order resonance in high intensity linear accelerators
For the 4σ = 360° spacecharge 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 fourfold 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 fourfold structure observed for input KapchinskijVladmirskij beams when σ < 90°, is not the fourth order resonance but a fourth order envelope instability because the 1/4more »
 Authors:

^{[1]}
;
^{[2]}
 Institute for Basic Science, Daejeon (South Korea)
 Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
 Publication Date:
 Grant/Contract Number:
 AC0205CH11231
 Type:
 Accepted Manuscript
 Journal Name:
 Physics of Plasmas
 Additional Journal Information:
 Journal Volume: 24; Journal Issue: 6; Journal ID: ISSN 1070664X
 Publisher:
 American Institute of Physics (AIP)
 Research Org:
 Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
 Sponsoring Org:
 USDOE Office of Science (SC)
 Country of Publication:
 United States
 Language:
 English
 Subject:
 43 PARTICLE ACCELERATORS
 OSTI Identifier:
 1436155
 Alternate Identifier(s):
 OSTI ID: 1364184
Jeon, D., and Hwang, Kyung Ryun. Characteristics of the fourth order resonance in high intensity linear accelerators. United States: N. p.,
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. 2017.
"Characteristics of the fourth order resonance in high intensity linear accelerators". United States.
doi:10.1063/1.4985685. https://www.osti.gov/servlets/purl/1436155.
@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° spacecharge 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 fourfold 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 fourfold structure observed for input KapchinskijVladmirskij 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 = {2017},
month = {6}
}