2011 Particle Accelerator Conference - Table of Session: TUOCN (Beam Dynamics IV)

Paper

Title

Page

Accurate Computation of Transfer Maps for Realistic Beamline Elements from Surface Data

742

C.E. Mitchell
NRL, Washington, DC, USA
A. Dragt
UMD, College Park, Maryland, USA

The behavior of orbits in charged-particle beam transport systems, including both linear and circular accelerators as well as final focus sections and spectrometers, can depend sensitively on nonlinear fringe-field and high-order-multipole effects in the various beam-line elements. The inclusion of these effects requires a detailed and realistic model of the interior and fringe fields, including their high spatial derivatives. A collection of surface fitting methods has been developed for extracting this information accurately from 3-dimensional field data on a grid, as provided by various 3-dimensional finite-element field codes. Based on these realistic field models, Lie or other methods may be used to compute accurate design orbits and accurate transfer maps about these orbits. This talk will provide a description of the methods along with example applications. An exactly-soluble but numerically challenging model field is used to provide a rigorous collection of performance benchmarks.

Slides TUOCN1 [1.630 MB]

TUOCN2

Spin-Manipulating Polarized Deuterons

747

V.S. Morozov
JLAB, Newport News, Virginia, USA
A. Chao
SLAC, Menlo Park, California, USA
F. Hinterberger
Universität Bonn, Helmholtz-Institut für Strahlen- und Kernphysik, Bonn, Germany
A.M. Kondratenko
GOO Zaryad, Novosibirsk, Russia
A.D. Krisch, M.A. Leonova, R.S. Raymond, D.W. Sivers, V.K. Wong
University of Michigan, Spin Physics Center, Ann Arbor, MI, USA
E.J. Stephenson
IUCF, Bloomington, Indiana, USA

Funding: This research was supported by grants from the German BMBF Science Ministry, its JCHP-FFE program at COSY and the US DOE.
Spin dynamics of polarized deuteron beams near depolarization resonances, including a new polarization preservation concept based on specially-designed multiple resonance crossings, has been tested in a series of experiments in the COSY synchrotron. Intricate spin dynamics with sophisticated pre-programmed patterns as well as effects of multiple crossings of a resonance were studied both theoretically and experimentally with excellent agreement. Possible applications of these results to preserve, manipulate and spin-flip polarized beams in synchrotrons and storage rings are discussed.

Slides TUOCN2 [4.921 MB]

TUOCN3

Application of the Eigen-Emittance Concept to Design Ultra-Bright Electron Beams

752

L.D. Duffy, K. Bishofberger, B.E. Carlsten, S.J. Russell, N.A. Yampolsky
LANL, Los Alamos, New Mexico, USA
A. Dragt
UMD, College Park, Maryland, USA
R.D. Ryne
LBNL, Berkeley, California, USA

Funding: We acknowledge the support of the U.S. Department of Energy through the LANL/LDRD Program.
Using correlations at the cathode to tailor the beam’s eigen-emittances is a recent concept made useful by the symplectic nature of Hamiltonian systems. While introducing correlations does not change the overall 6-dimensional phase space volume, it can change the partitioning of this volume into the longitudinal and two transverse emittances, which become the eigen-emittances if the initial correlations are removed. In principle, this technique can be used to generate beams with highly asymmetric emittances, such as those needed for the next generation of very hard X-ray free-electron lasers. Based on linear correlations, the applicability of this approach is limited by the magnitude of nonlinear effects in photoinjectors. We review the eigen-emittance concept and present a linear eigen-emittance design leading to a highly partitioned, and transversely ultra-bright, electron beam. We also present numerical tools to examine the evolution of the eigen-emittances in realistic accelerator structures and results indicating how much partitioning is practical.

Slides TUOCN3 [0.530 MB]

TUOCN4

Subpicosecond Electron Bunch Train Production Using a Phase-Space Exchange Technique

755

Y.-E. Sun, A.S. Johnson, A.H. Lumpkin, J. Ruan, R.M. Thurman-Keup
Fermilab, Batavia, USA
T.J. Maxwell, P. Piot
Northern Illinois University, DeKalb, Illinois, USA

Funding: The work was supported by the Fermi Research Alliance, LLC under the DOE Contract No. DE-AC02-07CH11359, and by Northern Illinois University under the DOE Contract No. DE-FG02-08ER41532.
Our recent experimental demonstration of a photoinjector electron bunch train with sub-picosecond structures is reported in this paper. The experiment is accomplished by converting an initially horizontal beam intensity modulation into a longitudinal phase space modulation, via a beamline capable of exchanging phase-space coordinates between the horizontal and longitudinal degrees of freedom. The initial transverse modulation is produced by intercepting the beam with a multislit mask prior to the exchange. We also compare our experimental results with numerical simulations.

Slides TUOCN4 [1.761 MB]

TUOCN5

Theoretical Study of Transverse-Longitudinal Emmittance Coupling

758

H. Qin, R.C. Davidson
PPPL, Princeton, New Jersey, USA
J.J. Barnard
LLNL, Livermore, California, USA
M. Chung
Handong Global University, Pohang, Republic of Korea
T.-S.F. Wang
LANL, Los Alamos, New Mexico, USA

Funding: Research supported by the U.S. Department of Energy.
The effect of a weakly coupled periodic lattice in terms of achieving emittance exchange between the transverse and longitudinal directions is investigated using the generalized Courant-Snyder theory for coupled lattices.
* H. Qin, M. Chung, and R. C. Davidson, PRL. 103, 224802 (2009).
** H. Qin and R. C. Davidson, PRST-AB 12, 064001 (2009).

Slides TUOCN5 [2.995 MB]

TUOCN6

Emittance Exchange and Bunch Compression

A. Zholents
ANL, Argonne, USA
M.S. Zolotorev
LBNL, Berkeley, California, USA

Funding: This work was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
Transverse to longitudinal emittance exchange was proposed in* as a tool for matching of the electron beam phase space to requirements of a possible application. Here we propose a new purpose, namely, use of two consequential emittance exchanges and the focusing telescope for a bunch compression that can be done without the energy chirp in the electron bunch. It allows to move bunch compressor to the end of the linac and thus to reduce the electron peak current in the linac and relax collective effects. It is also possible to have a split action compression when the first part is done inside the low energy part of the linac and the second and final part is done after the linac. We also demonstrate how proposed bunch compressor can be used for frequency up conversion of the energy modulation provided by laser interacting with the electron beam and thus can prepare a significantly higher frequency seed for seeded free-electron lasers. Same approach can be used for a frequency down conversion that can be useful for a generation of a THz radiation. Finally we note that the proposed bunch compression is practically free from destructive effects of coherent synchrotron radiation.
* M. Cornacchia, P. Emma, Phys. Rev. Spec. Topics – Acc. and Beams, 5, 084001(2002).

Slides TUOCN6 [5.347 MB]

Paper	Title	Page
TUOCN1	Accurate Computation of Transfer Maps for Realistic Beamline Elements from Surface Data	742
	C.E. Mitchell NRL, Washington, DC, USA A. Dragt UMD, College Park, Maryland, USA
	The behavior of orbits in charged-particle beam transport systems, including both linear and circular accelerators as well as final focus sections and spectrometers, can depend sensitively on nonlinear fringe-field and high-order-multipole effects in the various beam-line elements. The inclusion of these effects requires a detailed and realistic model of the interior and fringe fields, including their high spatial derivatives. A collection of surface fitting methods has been developed for extracting this information accurately from 3-dimensional field data on a grid, as provided by various 3-dimensional finite-element field codes. Based on these realistic field models, Lie or other methods may be used to compute accurate design orbits and accurate transfer maps about these orbits. This talk will provide a description of the methods along with example applications. An exactly-soluble but numerically challenging model field is used to provide a rigorous collection of performance benchmarks.
	Slides TUOCN1 [1.630 MB]

TUOCN2	Spin-Manipulating Polarized Deuterons	747
	V.S. Morozov JLAB, Newport News, Virginia, USA A. Chao SLAC, Menlo Park, California, USA F. Hinterberger Universität Bonn, Helmholtz-Institut für Strahlen- und Kernphysik, Bonn, Germany A.M. Kondratenko GOO Zaryad, Novosibirsk, Russia A.D. Krisch, M.A. Leonova, R.S. Raymond, D.W. Sivers, V.K. Wong University of Michigan, Spin Physics Center, Ann Arbor, MI, USA E.J. Stephenson IUCF, Bloomington, Indiana, USA
	Funding: This research was supported by grants from the German BMBF Science Ministry, its JCHP-FFE program at COSY and the US DOE. Spin dynamics of polarized deuteron beams near depolarization resonances, including a new polarization preservation concept based on specially-designed multiple resonance crossings, has been tested in a series of experiments in the COSY synchrotron. Intricate spin dynamics with sophisticated pre-programmed patterns as well as effects of multiple crossings of a resonance were studied both theoretically and experimentally with excellent agreement. Possible applications of these results to preserve, manipulate and spin-flip polarized beams in synchrotrons and storage rings are discussed.
	Slides TUOCN2 [4.921 MB]

TUOCN3	Application of the Eigen-Emittance Concept to Design Ultra-Bright Electron Beams	752
	L.D. Duffy, K. Bishofberger, B.E. Carlsten, S.J. Russell, N.A. Yampolsky LANL, Los Alamos, New Mexico, USA A. Dragt UMD, College Park, Maryland, USA R.D. Ryne LBNL, Berkeley, California, USA
	Funding: We acknowledge the support of the U.S. Department of Energy through the LANL/LDRD Program. Using correlations at the cathode to tailor the beam’s eigen-emittances is a recent concept made useful by the symplectic nature of Hamiltonian systems. While introducing correlations does not change the overall 6-dimensional phase space volume, it can change the partitioning of this volume into the longitudinal and two transverse emittances, which become the eigen-emittances if the initial correlations are removed. In principle, this technique can be used to generate beams with highly asymmetric emittances, such as those needed for the next generation of very hard X-ray free-electron lasers. Based on linear correlations, the applicability of this approach is limited by the magnitude of nonlinear effects in photoinjectors. We review the eigen-emittance concept and present a linear eigen-emittance design leading to a highly partitioned, and transversely ultra-bright, electron beam. We also present numerical tools to examine the evolution of the eigen-emittances in realistic accelerator structures and results indicating how much partitioning is practical.
	Slides TUOCN3 [0.530 MB]

TUOCN4	Subpicosecond Electron Bunch Train Production Using a Phase-Space Exchange Technique	755
	Y.-E. Sun, A.S. Johnson, A.H. Lumpkin, J. Ruan, R.M. Thurman-Keup Fermilab, Batavia, USA T.J. Maxwell, P. Piot Northern Illinois University, DeKalb, Illinois, USA
	Funding: The work was supported by the Fermi Research Alliance, LLC under the DOE Contract No. DE-AC02-07CH11359, and by Northern Illinois University under the DOE Contract No. DE-FG02-08ER41532. Our recent experimental demonstration of a photoinjector electron bunch train with sub-picosecond structures is reported in this paper. The experiment is accomplished by converting an initially horizontal beam intensity modulation into a longitudinal phase space modulation, via a beamline capable of exchanging phase-space coordinates between the horizontal and longitudinal degrees of freedom. The initial transverse modulation is produced by intercepting the beam with a multislit mask prior to the exchange. We also compare our experimental results with numerical simulations.
	Slides TUOCN4 [1.761 MB]

TUOCN5	Theoretical Study of Transverse-Longitudinal Emmittance Coupling	758
	H. Qin, R.C. Davidson PPPL, Princeton, New Jersey, USA J.J. Barnard LLNL, Livermore, California, USA M. Chung Handong Global University, Pohang, Republic of Korea T.-S.F. Wang LANL, Los Alamos, New Mexico, USA
	Funding: Research supported by the U.S. Department of Energy. The effect of a weakly coupled periodic lattice in terms of achieving emittance exchange between the transverse and longitudinal directions is investigated using the generalized Courant-Snyder theory for coupled lattices. * H. Qin, M. Chung, and R. C. Davidson, PRL. 103, 224802 (2009). ** H. Qin and R. C. Davidson, PRST-AB 12, 064001 (2009).
	Slides TUOCN5 [2.995 MB]

TUOCN6	Emittance Exchange and Bunch Compression
	A. Zholents ANL, Argonne, USA M.S. Zolotorev LBNL, Berkeley, California, USA
	Funding: This work was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. Transverse to longitudinal emittance exchange was proposed in* as a tool for matching of the electron beam phase space to requirements of a possible application. Here we propose a new purpose, namely, use of two consequential emittance exchanges and the focusing telescope for a bunch compression that can be done without the energy chirp in the electron bunch. It allows to move bunch compressor to the end of the linac and thus to reduce the electron peak current in the linac and relax collective effects. It is also possible to have a split action compression when the first part is done inside the low energy part of the linac and the second and final part is done after the linac. We also demonstrate how proposed bunch compressor can be used for frequency up conversion of the energy modulation provided by laser interacting with the electron beam and thus can prepare a significantly higher frequency seed for seeded free-electron lasers. Same approach can be used for a frequency down conversion that can be useful for a generation of a THz radiation. Finally we note that the proposed bunch compression is practically free from destructive effects of coherent synchrotron radiation. * M. Cornacchia, P. Emma, Phys. Rev. Spec. Topics – Acc. and Beams, 5, 084001(2002).
	Slides TUOCN6 [5.347 MB]