skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Relation between field energy and RMS emittance in intense particle beams

Abstract

An equation is presented for continuous beams with azimuthal symmetry and continuous linear focusing, which expresses a relationship between the rate of change for squared rms emittance and the rate of change for a quantity we call the nonlinear field energy. The nonlinear field energy depends on the shape of the charge distribution and corresponds to the residual field energy possessed by beams with nonuniform charge distributions. The equation can be integrated for the case of an rms matched beam to yield a formula for space-charge-induced emittance growth that we have tested numerically for a variety of initial distributions. The results provide a framework for discussing the scaling of rms emittance growth and an explanation for the well-established lower limit on output emittance. 15 refs., 4 figs.

Authors:
; ; ;
Publication Date:
Research Org.:
Los Alamos National Lab., NM (USA); Maryland Univ., College Park (USA)
OSTI Identifier:
5735912
Report Number(s):
LA-UR-85-1622; CONF-850504-58
ON: DE85012655
DOE Contract Number:
W-7405-ENG-36
Resource Type:
Conference
Resource Relation:
Conference: Particle accelerator conference, Vancouver, Canada, 13 May 1985
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; PARTICLE BEAMS; BEAM EMITTANCE; SIMULATION; BEAM DYNAMICS; NUMERICAL SOLUTION; OSCILLATIONS; SPACE CHARGE; BEAMS; 430200* - Particle Accelerators- Beam Dynamics, Field Calculations, & Ion Optics

Citation Formats

Wangler, T.P., Crandall, K.R., Mills, R.S., and Reiser, M. Relation between field energy and RMS emittance in intense particle beams. United States: N. p., 1985. Web.
Wangler, T.P., Crandall, K.R., Mills, R.S., & Reiser, M. Relation between field energy and RMS emittance in intense particle beams. United States.
Wangler, T.P., Crandall, K.R., Mills, R.S., and Reiser, M. Tue . "Relation between field energy and RMS emittance in intense particle beams". United States. doi:. https://www.osti.gov/servlets/purl/5735912.
@article{osti_5735912,
title = {Relation between field energy and RMS emittance in intense particle beams},
author = {Wangler, T.P. and Crandall, K.R. and Mills, R.S. and Reiser, M.},
abstractNote = {An equation is presented for continuous beams with azimuthal symmetry and continuous linear focusing, which expresses a relationship between the rate of change for squared rms emittance and the rate of change for a quantity we call the nonlinear field energy. The nonlinear field energy depends on the shape of the charge distribution and corresponds to the residual field energy possessed by beams with nonuniform charge distributions. The equation can be integrated for the case of an rms matched beam to yield a formula for space-charge-induced emittance growth that we have tested numerically for a variety of initial distributions. The results provide a framework for discussing the scaling of rms emittance growth and an explanation for the well-established lower limit on output emittance. 15 refs., 4 figs.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Jan 01 00:00:00 EST 1985},
month = {Tue Jan 01 00:00:00 EST 1985}
}

Conference:
Other availability
Please see Document Availability for additional information on obtaining the full-text document. Library patrons may search WorldCat to identify libraries that hold this conference proceeding.

Save / Share:
  • An equation is presented for continuous beams with azimuthal symmetry and continuous linear focusing, which expresses a relationship between the rate of change for squared rms emittance and the rate of change for a quantity we call the nonlinear field energy. The nonlinear field energy depends on the shape of the charge distribution and corresponds to the residual field energy possessed by beams with nonuniform charge distributions. The equation can be integrated for the case of an rms matched beam to yield a formula for space-charge-induced emittance growth that we have tested numerically for a variety of initial distributions. Themore » results provide a framework for discussing the scaling of rms emittance growth and an explanation for the well-established lower limit on output emittance.« less
  • An equation is presented for continuous beam with azimuthal symmetry and continuous linear focusing; the equation expresses a relationship between the rate of change for squared rms emittance and the rate of change for a quantity we call the nonlinear field energy. The nonlinear field energy depends on the shape of the charge distribution and corresponds to the residual field energy possessed by beams with nonuniform charge distributions. The equation can be integrated for the case of an rms matched beam to yield a formula for space-charge-induced emittance growth that we have tested numerically for a variety of initial distributions.more » The results provide a framework for discussing the scaling of rms emittance growth and an explanation for the well-established lower limit on output emittance.« less
  • We combine the ideas of kinetic energy equipartitioning and nonlinear field energy to obtain a quantitative description for rms emittance changes induced in intense beams with two degrees of freedom. We derive equations for emittance change in each plane for continuous elliptical beams and axially symmetric bunched beams, with arbitrary initial charge distributions within a constant focusing channel. The complex details of the mechanisms leading to kinetic energy transfer are not necessary to obtain the formulas. The resulting emittance growth equations contain two separate terms: the first describes emittance changes associated with the transfer of energy between the two planes;more » the second describes emittance growth associated with the transfer of nonlinear field energy into kinetic energy as the charge distribution changes.« less
  • An emittance scanner has been developed for use with low-energy H- ion beams to satisfy the following requirements: angular resolution of + or - 1/2 mrad, small errors from beam space charge, and compact and simple design. The scanner consists of a 10-cm-long analyzer containing two slits and a pair of electric deflection plates driven by a + or - 500-V linear ramp generator. As the analyzer is mechanically driven across the beam, the front slit passes a thin ribbon of beam through the plates. The ion transit time is short compared with the ramp speed; therefore, the initial anglemore » of the ions that pass through the rear slit is proportional to the instantaneous ramp voltage. The current through the rear slit then is proportional to the phase-space density d/sup 2/i/dxdx'. The data are computer-analyzed to give, for example, rms emittance and phase-space density contours. Comparison of measured data with those calculated from a prepared (collimated) phase space is in good agreement.« less
  • An emittance scanner has been developed for use with low-energy H/sup -/ ion beams to satisfy the following requirements: (1) angular resolution of +-1/2 mrad, (2) small errors from beam space charge, and (3) compact and simple design. The scanner consists of a 10-cm-long analyzer containing two slits and a pair of electric deflection plates driven by a +-500-V linear ramp generator. As the analyzer is mechanically driven across the beam, the front slit passes a thin ribbon of beam through the plates. The ion transit time is short compared with the ramp speed; therefore, the initial angle of themore » ions that pass through the rear slit is proportional to the instantaneous ramp voltage. The current through the rear slit then is proportional to the phase-space density d/sup 2/i/dxdx'. The data are computer-analyzed to give, for example, rms emittance and phase-space density contours. Comparison of measured data with those calculated from a prepared (collimated) phase space is in good agreement.« less