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Title: Corkscrew Motion of an Electron Beam due to Coherent Variations in Accelerating Potentials

Abstract

Corkscrew motion results from the interaction of fluctuations of beam electron energy with accidental magnetic dipoles caused by misalignment of the beam transport solenoids. Corkscrew is a serious concern for high-current linear induction accelerators (LIA). A simple scaling law for corkscrew amplitude derived from a theory based on a constant-energy beam coasting through a uniform magnetic field has often been used to assess LIA vulnerability to this effect. We use a beam dynamics code to verify that this scaling also holds for an accelerated beam in a non-uniform magnetic field, as in a real accelerator. Results of simulations with this code are strikingly similar to measurements on one of the LIAs at Los Alamos National Laboratory.

Authors:
 [1]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1324545
Report Number(s):
LA-UR-16-26989
TRN: US1700056
DOE Contract Number:
AC52-06NA25396
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; INDUCTION; INTERACTIONS; SIMULATION; ELECTRON BEAMS; FLUCTUATIONS; SCALING LAWS; LANL; SOLENOIDS; BEAM DYNAMICS; MAGNETIC DIPOLES; MAGNETIC FIELDS; ACCELERATORS; ELECTRIC POTENTIAL; BEAM BENDING MAGNETS; AMPLITUDES; KILO AMP BEAM CURRENTS; L CODES; linear induction accelerators; electron beam dynamics; electron beam stability

Citation Formats

Ekdahl, Carl August. Corkscrew Motion of an Electron Beam due to Coherent Variations in Accelerating Potentials. United States: N. p., 2016. Web. doi:10.2172/1324545.
Ekdahl, Carl August. Corkscrew Motion of an Electron Beam due to Coherent Variations in Accelerating Potentials. United States. doi:10.2172/1324545.
Ekdahl, Carl August. 2016. "Corkscrew Motion of an Electron Beam due to Coherent Variations in Accelerating Potentials". United States. doi:10.2172/1324545. https://www.osti.gov/servlets/purl/1324545.
@article{osti_1324545,
title = {Corkscrew Motion of an Electron Beam due to Coherent Variations in Accelerating Potentials},
author = {Ekdahl, Carl August},
abstractNote = {Corkscrew motion results from the interaction of fluctuations of beam electron energy with accidental magnetic dipoles caused by misalignment of the beam transport solenoids. Corkscrew is a serious concern for high-current linear induction accelerators (LIA). A simple scaling law for corkscrew amplitude derived from a theory based on a constant-energy beam coasting through a uniform magnetic field has often been used to assess LIA vulnerability to this effect. We use a beam dynamics code to verify that this scaling also holds for an accelerated beam in a non-uniform magnetic field, as in a real accelerator. Results of simulations with this code are strikingly similar to measurements on one of the LIAs at Los Alamos National Laboratory.},
doi = {10.2172/1324545},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2016,
month = 9
}

Technical Report:

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  • In this paper, the authors present a new formulation for the longitudinal coherent dipole motion, where a quadrature response of the environmental impedance is shown to be the effective longitudinal impedance for the beam instability. The Robinson-Pedersen formulation for the longitudinal dipole motion is also presented, the difference of the two approaches is discussed in the comparison. The results by using the Sacherer integral equation for the coherent dipole motion can generate the same results as by using the other two approaches, except for a scaling difference. The formulation is further generalized to the rigid bunch motion using signal analysismore » method, where a form factor shows up naturally. Finally, the formulation is applied to solve the coupled bunch instabilities. Examples of the AGS Booster and the AGS coupled bunch instabilities are used to illustrate the applications of the formulation.« less