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Title: Generalized parametrization methods for centroid and envelope dynamics of charged particle beams in coupled lattices

Authors:
 [1];  [2]
  1. Department of Physics, Ulsan National Institute of Science and Technology, Ulsan 44919, South Korea
  2. Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543, USA, Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1414617
Grant/Contract Number:
AC02-09CH11466
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 25; Journal Issue: 1; Related Information: CHORUS Timestamp: 2017-12-22 10:43:04; Journal ID: ISSN 1070-664X
Publisher:
American Institute of Physics
Country of Publication:
United States
Language:
English

Citation Formats

Chung, Moses, and Qin, Hong. Generalized parametrization methods for centroid and envelope dynamics of charged particle beams in coupled lattices. United States: N. p., 2018. Web. doi:10.1063/1.5018426.
Chung, Moses, & Qin, Hong. Generalized parametrization methods for centroid and envelope dynamics of charged particle beams in coupled lattices. United States. doi:10.1063/1.5018426.
Chung, Moses, and Qin, Hong. 2018. "Generalized parametrization methods for centroid and envelope dynamics of charged particle beams in coupled lattices". United States. doi:10.1063/1.5018426.
@article{osti_1414617,
title = {Generalized parametrization methods for centroid and envelope dynamics of charged particle beams in coupled lattices},
author = {Chung, Moses and Qin, Hong},
abstractNote = {},
doi = {10.1063/1.5018426},
journal = {Physics of Plasmas},
number = 1,
volume = 25,
place = {United States},
year = 2018,
month = 1
}

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on December 22, 2018
Publisher's Accepted Manuscript

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  • The centroid and envelope dynamics of a high-intensity charged-particle beam are investigated as a beam smoothing technique to achieve uniform illumination over a suitably chosen region of the target for applications to ion-beam-driven high energy density physics and heavy ion fusion. The motion of the beam centroid projected onto the target follows a smooth pattern to achieve the desired illumination, for improved stability properties during the beam-target interaction. The centroid dynamics is controlled by an oscillating 'wobbler', a set of electrically biased plates driven by rf voltage.
  • In this paper we analyze the combined envelope-centroid dynamics of magnetically focused high-intensity charged beams surrounded by conducting walls. Similar to the case where conducting walls are absent, it is shown that the envelope and centroid dynamics decouple from each other. Mismatched envelopes still decay into equilibrium with simultaneous emittance growth, but the centroid keeps oscillating with no appreciable energy loss. Some estimates are performed to analytically obtain characteristics of halo formation seen in the full simulations.
  • The dynamics of charged particles in general linear focusing lattices with quadrupole, skew-quadrupole, dipole, and solenoidal components, as well as torsion of the fiducial orbit and variation of beam energy is parametrized using a generalized Courant-Snyder (CS) theory, which extends the original CS theory for one degree of freedom to higher dimensions. The envelope function is generalized into an envelope matrix, and the phase advance is generalized into a 4D symplectic rotation, or a Uð2Þ element. The 1D envelope equation, also known as the Ermakov-Milne-Pinney equation in quantum mechanics, is generalized to an envelope matrix equation in higher dimensions. Othermore » components of the original CS theory, such as the transfer matrix, Twiss functions, and CS invariant (also known as the Lewis invariant) all have their counterparts, with remarkably similar expressions, in the generalized theory. The gauge group structure of the generalized theory is analyzed. By fixing the gauge freedom with a desired symmetry, the generalized CS parametrization assumes the form of the modified Iwasawa decomposition, whose importance in phase space optics and phase space quantum mechanics has been recently realized. This gauge fixing also symmetrizes the generalized envelope equation and expresses the theory using only the generalized Twiss function β. The generalized phase advance completely determines the spectral and structural stability properties of a general focusing lattice. For structural stability, the generalized CS theory enables application of the Krein-Moser theory to greatly simplify the stability analysis. The generalized CS theory provides an effective tool to study coupled dynamics and to discover more optimized lattice designs in the larger parameter space of general focusing lattices.« less