IPAC2012 - Table of Session: TUOAA (Contributed Oral Presentations (Beam Dynamics and Electromagnetic Fields))

Paper

Title

Page

3-Dimensional Modeling of Electron Clouds in Non-uniform Magnetic Fields

1059

S.A. Veitzer, P. Stoltz
Tech-X, Boulder, Colorado, USA
J.A. Crittenden, K.G. Sonnad
CLASSE, Ithaca, New York, USA

Funding: This work was performed under the auspices of the Department of Energy as part of the ComPASS SCiDAC-2 project (DE-FC02-07ER41499) and by the National Science Foundation Grant PHY-0734867.
Electron clouds have the potential to pose serious limitations on accelerator performance in both hadron and lepton beams. Experiments using rf diagnostics are being performed to measure electron cloud densities at a number of accelerator facilities. However, it is difficult to calibrate plasma density with signal strength in these experiments, and modeling involves a number of technical and numerical challenges. Typically 2-Dimensional electrostatic methods have been used to model cloud buildup under beam crossing conditions. However, since traveling-wave rf experiments typically occur over many meters of beam pipe where magnetic fields are changing, one needs to develop 3-Dimensional electromagnetic models in order to accurately simulate rf diagnostics. We have developed accurate models of electron cloud-induced phase shifts in rf in a system with spatially varying magnetic field configurations using the plasma simulation code VORPAL. We present here results for measuring phase shifts in the CESR wiggler with realistic, spatially non-uniform magnetic field configurations.

Slides TUOAA01 [18.367 MB]

TUOAA02

Focusing Charged Particle Beams Using Multipole Magnets in a Beam Transport Line

1062

Y. Yuri, I. Ishibori, T. Ishizaka, S. Okumura, T. Yuyama
JAEA/TARRI, Gunma-ken, Japan

The intensity distribution of a charged-particle beam is transformed by applying the nonlinear focusing force of a multipole magnet. In this paper, the transformation of the transverse intensity distribution due to the second-order sextupole and third-order octupole focusing force in the beam transport line is explored. As a measure of the distribution transformation induced by the multipole magnets, the beam centroid displacement and the change of the beam size have been analytically derived using the distribution function of the beam. It is numerically verified how the transverse distribution of the beam is transformed by the multipole magnets. As an application of the distribution transformation by nonlinear focusing, a uniform beam can be formed from a Gaussian beam using multipole magnets. The current status and future plan of the experiment on the uniform-beam formation at the cyclotron facility in Japan Atomic Energy Agency will be shown.

Slides TUOAA02 [2.032 MB]

TUOAA03

Tests of Low Emittance Tuning Techniques at SLS and DAΦNE

1065

S.M. Liuzzo, M.E. Biagini, P. Raimondi
INFN/LNF, Frascati (Roma), Italy
M. Aiba
Paul Scherrer Institut, Villigen, Switzerland
M. Böge
PSI, Villigen, Switzerland

The SuperB collider design is based on extremely low emittances, comparable to those of synchrotron light sources. A Low Emittance Tuning (LET) algorithm was developed for SuperB and has been tested last year at DIAMOND. This paper will report on the results of the application of LET to SLS (PSI) and DAΦNE (LNF) in order to compare and confirm the previous results. In this tests, the correction of orbit, dispersion and coupling is applied simultaneously to the detection of Beam Position Monitors tilts. The effect of beam based alignment at DAΦNE is also presented, together with an evaluation of the effects of other possible sources of emittance growth.

Slides TUOAA03 [4.313 MB]

Paper	Title	Page
TUOAA01	3-Dimensional Modeling of Electron Clouds in Non-uniform Magnetic Fields	1059
	S.A. Veitzer, P. Stoltz Tech-X, Boulder, Colorado, USA J.A. Crittenden, K.G. Sonnad CLASSE, Ithaca, New York, USA
	Funding: This work was performed under the auspices of the Department of Energy as part of the ComPASS SCiDAC-2 project (DE-FC02-07ER41499) and by the National Science Foundation Grant PHY-0734867. Electron clouds have the potential to pose serious limitations on accelerator performance in both hadron and lepton beams. Experiments using rf diagnostics are being performed to measure electron cloud densities at a number of accelerator facilities. However, it is difficult to calibrate plasma density with signal strength in these experiments, and modeling involves a number of technical and numerical challenges. Typically 2-Dimensional electrostatic methods have been used to model cloud buildup under beam crossing conditions. However, since traveling-wave rf experiments typically occur over many meters of beam pipe where magnetic fields are changing, one needs to develop 3-Dimensional electromagnetic models in order to accurately simulate rf diagnostics. We have developed accurate models of electron cloud-induced phase shifts in rf in a system with spatially varying magnetic field configurations using the plasma simulation code VORPAL. We present here results for measuring phase shifts in the CESR wiggler with realistic, spatially non-uniform magnetic field configurations.
	Slides TUOAA01 [18.367 MB]

TUOAA02	Focusing Charged Particle Beams Using Multipole Magnets in a Beam Transport Line	1062
	Y. Yuri, I. Ishibori, T. Ishizaka, S. Okumura, T. Yuyama JAEA/TARRI, Gunma-ken, Japan
	The intensity distribution of a charged-particle beam is transformed by applying the nonlinear focusing force of a multipole magnet. In this paper, the transformation of the transverse intensity distribution due to the second-order sextupole and third-order octupole focusing force in the beam transport line is explored. As a measure of the distribution transformation induced by the multipole magnets, the beam centroid displacement and the change of the beam size have been analytically derived using the distribution function of the beam. It is numerically verified how the transverse distribution of the beam is transformed by the multipole magnets. As an application of the distribution transformation by nonlinear focusing, a uniform beam can be formed from a Gaussian beam using multipole magnets. The current status and future plan of the experiment on the uniform-beam formation at the cyclotron facility in Japan Atomic Energy Agency will be shown.
	Slides TUOAA02 [2.032 MB]

TUOAA03	Tests of Low Emittance Tuning Techniques at SLS and DAΦNE	1065
	S.M. Liuzzo, M.E. Biagini, P. Raimondi INFN/LNF, Frascati (Roma), Italy M. Aiba Paul Scherrer Institut, Villigen, Switzerland M. Böge PSI, Villigen, Switzerland
	The SuperB collider design is based on extremely low emittances, comparable to those of synchrotron light sources. A Low Emittance Tuning (LET) algorithm was developed for SuperB and has been tested last year at DIAMOND. This paper will report on the results of the application of LET to SLS (PSI) and DAΦNE (LNF) in order to compare and confirm the previous results. In this tests, the correction of orbit, dispersion and coupling is applied simultaneously to the detection of Beam Position Monitors tilts. The effect of beam based alignment at DAΦNE is also presented, together with an evaluation of the effects of other possible sources of emittance growth.
	Slides TUOAA03 [4.313 MB]