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Title: Transverse Phase Space Measurement Using Tomographic Method

Abstract

Transverse phase space tomography using a set of a quadrupole magnet and a beam profile monitor is useful method to measure phase space distribution of electron beams. However, the energy distribution of measured beam distorts result of the tomographic method, since the assumption of a mono-energetic beam is essential in this method. In order to evaluate the effect of energy distribution, the numerical simulation was carried out. As the result of simulation, we found that the energy spread of the main component does not have significant effects, but the low energetic tail severely distorts the reconstructed phase space distribution. However, the center core was preserved in the distorted image. Therefore an elliptical analysis method was introduced to pick up the center core information as precise as possible. By using this method, we could obtain the Twiss parameters and emittance of center core which are almost consistent with initial distribution.

Authors:
; ; ; ; ; ; ; ;  [1]
  1. Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan)
Publication Date:
OSTI Identifier:
21049359
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 879; Journal Issue: 1; Conference: 9. international conference on synchrotron radiation instrumentation, Daegu (Korea, Republic of), 28 May - 2 Jun 2006; Other Information: DOI: 10.1063/1.2436046; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; BEAM MONITORING; BEAM MONITORS; BEAM PROFILES; COMPUTERIZED SIMULATION; DISTRIBUTION; ELECTRON BEAMS; ENERGY SPECTRA; IMAGES; MAGNETS; PHASE SPACE; QUADRUPOLES; TOMOGRAPHY

Citation Formats

Zen, Heishun, Ohgaki, Hideaki, Masuda, Kai, Kii, Toshiteru, Kusukame, Kohichi, Fukui, Toshio, Nakai, Yoko, Yamazaki, Tetsuo, and Yoshikawa, Kiyoshi. Transverse Phase Space Measurement Using Tomographic Method. United States: N. p., 2007. Web. doi:10.1063/1.2436046.
Zen, Heishun, Ohgaki, Hideaki, Masuda, Kai, Kii, Toshiteru, Kusukame, Kohichi, Fukui, Toshio, Nakai, Yoko, Yamazaki, Tetsuo, & Yoshikawa, Kiyoshi. Transverse Phase Space Measurement Using Tomographic Method. United States. doi:10.1063/1.2436046.
Zen, Heishun, Ohgaki, Hideaki, Masuda, Kai, Kii, Toshiteru, Kusukame, Kohichi, Fukui, Toshio, Nakai, Yoko, Yamazaki, Tetsuo, and Yoshikawa, Kiyoshi. Fri . "Transverse Phase Space Measurement Using Tomographic Method". United States. doi:10.1063/1.2436046.
@article{osti_21049359,
title = {Transverse Phase Space Measurement Using Tomographic Method},
author = {Zen, Heishun and Ohgaki, Hideaki and Masuda, Kai and Kii, Toshiteru and Kusukame, Kohichi and Fukui, Toshio and Nakai, Yoko and Yamazaki, Tetsuo and Yoshikawa, Kiyoshi},
abstractNote = {Transverse phase space tomography using a set of a quadrupole magnet and a beam profile monitor is useful method to measure phase space distribution of electron beams. However, the energy distribution of measured beam distorts result of the tomographic method, since the assumption of a mono-energetic beam is essential in this method. In order to evaluate the effect of energy distribution, the numerical simulation was carried out. As the result of simulation, we found that the energy spread of the main component does not have significant effects, but the low energetic tail severely distorts the reconstructed phase space distribution. However, the center core was preserved in the distorted image. Therefore an elliptical analysis method was introduced to pick up the center core information as precise as possible. By using this method, we could obtain the Twiss parameters and emittance of center core which are almost consistent with initial distribution.},
doi = {10.1063/1.2436046},
journal = {AIP Conference Proceedings},
number = 1,
volume = 879,
place = {United States},
year = {Fri Jan 19 00:00:00 EST 2007},
month = {Fri Jan 19 00:00:00 EST 2007}
}
  • Tomography is the technique of reconstructing an image from its projections. It is widely used in the medical community to observe the interior of the human body by processing multiple x-ray images taken at different angles, A few pioneering researchers have adapted tomography to reconstruct detailed phase space maps of charged particle beams. Some questions arise regarding the limitations of tomography technique for space charge dominated beams. For instance is the linear space charge force a valid approximation? Does tomography equally reproduce phase space for complex, experimentally observed, initial particle distributions? Does tomography make any assumptions about the initial distribution?more » This study explores the use of accurate modeling with the particle-in-cell code WARP to address these questions, using a wide range of different initial distributions in the code. The study also includes a number of experimental results on tomographic phase space mapping performed on University of Maryland Electron Ring (UMER)« less
  • A model is described for tomographic phase-space mapping and emittance measurement in beams with space-charge. The tomographic results of an experiment with a 10 keV space-charge dominated electron beam are presented. The data are compared against a direct experimental sampling of the phase-space using a pinhole scan. It is found that the accuracy of the tomographic method is within 10% for beams with space-charge intensity less than 90%. With the aid of numerical simulation the observed similarities and differences between the tomography method and pinhole scan are discussed.
  • A facility to monitor intense beams of charged particles in vacuum automatically has been designed. The coordinate resolution and measurement accuracy is considerably improved by using a sophisticated correction method for the spread function of the beam probe, by statistical data processing, and by automatically determining the beam axis. Profiles of an electron beam with a half-width of {approx}0.5 mm and a power density of 10{sup 9}W/m{sup 2} have been measured for several sequential cross sections. This technique allows us to derive distribution functions in charged particle beams along two-, three-, and four-dimensional transverse trajectories, and, if the beam ismore » monoenergetic, the distribution function can be derived in phase space from a set of one-dimensional projections without any a priori knowledge of the shapes of the isosurfaces of the distribution functions. Diagrams of the current density in an intense (2{center_dot}10{sup 9}W/m{sup 2}) narrow ({approximately}0.5 mm) electron beam in two- and three-dimensional transverse trajectory spaces in several sequential cross sections have been derived from a set of one-dimensional projections. Both divergent and convergent components have been detected in a nonlaminar beam.« less
  • Tomography based on quadrupole scans has been successfully applied to reconstruct the phase space of intense charged particle beams. This letter develops a tomographic technique based on solenoid scans, which is advantageous for solenoidal systems and injectors. The technique is generalized to the diagnosis of beams that are not axisymmetric, and validated through simulation. Solenoidal tomography is applied experimentally to a system with a nonequilibrium initial distribution, demonstrating its detailed evolution in phase space.
  • We report on the experimental generation of a train of subpicosecond electron bunches. The bunch train generation is accomplished using a beamline capable of exchanging the coordinates between the horizontal and longitudinal degrees of freedom. An initial beam consisting of a set of horizontally-separated beamlets is converted into a train of bunches temporally separated with tunable bunch duration and separation. The experiment reported in this Letter unambiguously demonstrates the conversion process and its versatility.