HB2012 - List of Authors (Beaudoin, B.L.)

Paper

Title

Page

Beam Halo Measurements using Adaptive Masking Methods and Proposed Recent Halo Experiment

215

H.D. Zhang, B.L. Beaudoin, S. Bernal, R.B. Fiorito, R.A. Kishek, K. Řežaei, A.G. Shkvarunets
UMD, College Park, Maryland, USA

Beam halo is a common phenomenon in particle beams, especially for modern, advanced accelerators where high beam intensities lead to strong space charge. Halo is generally understood as a population of particles that do, or will, reach large transverse radii relative to a more intense, centralized beam core. It is associated with emittance growth, beam quality degradation and particle loss. The particle-core model [1] is commonly used to describe halo formation as the result of a parametric resonance due to envelope mismatch. Few experiments have been carried out to test this theory [2]. Measurement of beam halo is particularly problematic for faint halos, where light from the intense core obscures the optical image of the halo. In this paper, we present a new diagnostic for high-dynamic range halo measurements based on adaptive masking of the beam core [3]. We also present the design of an experiment to study halo formation from envelope mismatch for beams spanning a wide range of intensities on the University of Maryland Electron Ring (UMER) [4].
[1] R. Gluckstern, Phys. Rev. Lett., vol.73, 1994.
[2] C. Allen, Phys. Rev. Lett. Vol 89, 1998
[3] H. Zhang, et al., Proc of PAC11.
[4] R.A. Kishek, these proceedings.

WEO1C05

Longitudinal Space Charge Phenomena in an Intense Beam in a Ring

447

R.A. Kishek, B.L. Beaudoin, D.W. Feldman, I. Haber, T.W. Koeth, Y. Mo
UMD, College Park, Maryland, USA

Funding: Supported by the US Dept. of Energy, Offices of High Energy Physics and Fusion Energy Sciences, and by the US Dept. of Defense, Office of Naval Research and the Joint Technology Office.
The University of Maryland Electron Ring (UMER) uses nonrelativistic, high-current electron beams to access the intense space charge dynamics applicable to hadron beams. The UMER beam parameters correspond to space charge incoherent tune shifts, at injection, in the range of 1-5.5 integers. Longitudinal induction focusing is used to counteract the space charge force at the edges of a long rectangular bunch, confining the beam for 100s of turns. We report on two recent findings: (1) The formation and propagation of solitons from large amplitude longitudinal perturbations, observed experimentally and reproduced in WARP* simulations. (2) The evolution of a longitudinal multi-streaming instability when the space-charge force is allowed to lengthen the bunch ends. The expanding bunch ends fill the ring, interpenetrate, and wrap repeatedly, forming multiple streams at any one location, each with its unique velocity. The resulting multi-stream instability is investigated over a wide range of beam currents and initial pulse lengths, and experimental observations are in good agreement with WARP simulations and an analytical theory that successfully predicts the onset of the instability.
* D.P. Grote, A. Friedman, I. Haber, S. Yu, Fus. Eng. & Des. 32-33, 193-200 (1996).

Slides WEO1C05 [5.868 MB]

Paper	Title	Page
MOP260	Beam Halo Measurements using Adaptive Masking Methods and Proposed Recent Halo Experiment	215
	H.D. Zhang, B.L. Beaudoin, S. Bernal, R.B. Fiorito, R.A. Kishek, K. Řežaei, A.G. Shkvarunets UMD, College Park, Maryland, USA
	Beam halo is a common phenomenon in particle beams, especially for modern, advanced accelerators where high beam intensities lead to strong space charge. Halo is generally understood as a population of particles that do, or will, reach large transverse radii relative to a more intense, centralized beam core. It is associated with emittance growth, beam quality degradation and particle loss. The particle-core model [1] is commonly used to describe halo formation as the result of a parametric resonance due to envelope mismatch. Few experiments have been carried out to test this theory [2]. Measurement of beam halo is particularly problematic for faint halos, where light from the intense core obscures the optical image of the halo. In this paper, we present a new diagnostic for high-dynamic range halo measurements based on adaptive masking of the beam core [3]. We also present the design of an experiment to study halo formation from envelope mismatch for beams spanning a wide range of intensities on the University of Maryland Electron Ring (UMER) [4]. [1] R. Gluckstern, Phys. Rev. Lett., vol.73, 1994. [2] C. Allen, Phys. Rev. Lett. Vol 89, 1998 [3] H. Zhang, et al., Proc of PAC11. [4] R.A. Kishek, these proceedings.

WEO1C05	Longitudinal Space Charge Phenomena in an Intense Beam in a Ring	447
	R.A. Kishek, B.L. Beaudoin, D.W. Feldman, I. Haber, T.W. Koeth, Y. Mo UMD, College Park, Maryland, USA
	Funding: Supported by the US Dept. of Energy, Offices of High Energy Physics and Fusion Energy Sciences, and by the US Dept. of Defense, Office of Naval Research and the Joint Technology Office. The University of Maryland Electron Ring (UMER) uses nonrelativistic, high-current electron beams to access the intense space charge dynamics applicable to hadron beams. The UMER beam parameters correspond to space charge incoherent tune shifts, at injection, in the range of 1-5.5 integers. Longitudinal induction focusing is used to counteract the space charge force at the edges of a long rectangular bunch, confining the beam for 100s of turns. We report on two recent findings: (1) The formation and propagation of solitons from large amplitude longitudinal perturbations, observed experimentally and reproduced in WARP* simulations. (2) The evolution of a longitudinal multi-streaming instability when the space-charge force is allowed to lengthen the bunch ends. The expanding bunch ends fill the ring, interpenetrate, and wrap repeatedly, forming multiple streams at any one location, each with its unique velocity. The resulting multi-stream instability is investigated over a wide range of beam currents and initial pulse lengths, and experimental observations are in good agreement with WARP simulations and an analytical theory that successfully predicts the onset of the instability. * D.P. Grote, A. Friedman, I. Haber, S. Yu, Fus. Eng. & Des. 32-33, 193-200 (1996).
	Slides WEO1C05 [5.868 MB]