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BL
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| Record Number
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859770
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| Main Entry
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Antipov, Sergey A.
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| Title & Author
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Fast transverse beam instability caused by electron cloud trapped in combined function magnets /\ Sergey A. Antipov.
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| Publication Statement
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Cham, Switzerland :: Springer,, 2018.
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| Series Statement
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Springer theses
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| Page. NO
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1 online resource :: illustrations (some colour)
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| ISBN
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3030024083
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: 9783030024086
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3030024075
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9783030024079
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| Notes
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"Doctoral thesis accepted by University of Chicago, Illinois, USA."
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| Bibliographies/Indexes
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Includes bibliographical references.
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| Contents
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Intro; Supervisorś Foreword; Acknowledgments; Contents; Parts of this thesis have been published in the following journal articles:; Chapter 1: Electron Cloud in Particle Accelerators; 1.1 Electron Cloud Build-Up; 1.1.1 Generation of Primary Electrons; 1.1.2 Secondary Emission; 1.1.3 Build-Up Regimes; 1.1.4 Effect of External Magnetic Field; 1.2 Electron Cloud Instabilities; 1.3 Electron Cloud Tune Shift; 1.4 Beampipe Conditioning; References; Chapter 2: Beam Dynamics Measurements of the Fast Instability; 2.1 Beam Manipulation and Diagnostics; 2.1.1 Beam Manipulation; 2.1.2 Ring Manipulation.
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2.1.3 Beam Diagnostics2.1.4 Factors Beyond Control; 2.2 Dynamics of the Unstable Beam; 2.2.1 Peculiar Features of the Instability; 2.2.2 Intensity Dependence of the Instability Growth Rate; 2.2.3 Conditioning During the High-Intensity Operation; 2.3 Beam Stabilization by a Clearing Bunch; 2.3.1 Possible Operational Implementation of Electron Cloud Clearing; References; Chapter 3: Microwave Measurement of the Cloud Density; 3.1 Experimental Setup; 3.1.1 Hardware; 3.1.2 Physical Principle; 3.1.3 Signal Transmission; 3.2 Schottky Noise; 3.2.1 Noise Spectrum.
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3.2.2 Schottky Noise on the Recycler BPMs3.2.3 Frequency Selection; 3.3 Measured Electron Cloud Density; 3.3.1 Density Versus Beam Intensity; 3.3.2 Electron Cloud Decay; References; Chapter 4: Numerical Simulation; 4.1 Electron Cloud Trapping in a Combined Function Magnet; 4.1.1 Combined Function Dipole as a Magnetic Trap; 4.1.2 Electron Capture by the Field; 4.1.3 Electron Cloud Clearing with a Witness Bunch; 4.1.4 Lifetime of the Trapped Cloud; 4.2 Numerical Model; 4.2.1 Model of the Beam; 4.2.2 Model of the Ring; 4.2.3 Model of the Electron Cloud; 4.2.4 Beam-Cloud Interaction.
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4.3 Electron Cloud Build-Up4.3.1 Dependence on the Secondary Emission; 4.3.2 Dependence on Bunch Length; 4.3.3 Saturation of the Electron Cloud; 4.3.4 Trapping in a Combined Function Magnet; 4.3.5 Clearing with a Witness Bunch; 4.3.6 Peak Density of the Electron Cloud; 4.3.7 Electron Cloud in Drift Sections; 4.4 Electron Cloud Instability; 4.4.1 Growth Rate; 4.4.2 Most Unstable Mode; References; Chapter 5: Analytical Model of the Electron Cloud Instability; 5.1 Model of the Beam-Cloud Interaction; 5.1.1 Coasting Beam; 5.1.2 Bunched Beam; 5.2 Fast Instability in Recycler.
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5.3 Instability at Higher Intensities5.4 Landau Damping of the Fast Instability Using Octupoles; References; Chapter 6: Conclusion.
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| Abstract
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This thesis presents profound insights into the origins and dynamics of beam instabilities using both experimental observations and numerical simulations. When the Recycler Ring, a high-intensity proton beam accelerator at Fermi National Accelerator Laboratory, was commissioned, it became evident that the Recycler beam experiences a very fast instability of unknown nature. This instability was so fast that the existing dampers were ineffective at suppressing it. The nature of this phenomenon, alongside several other poorly understood features of the beam, became one of the biggest puzzles in the accelerator community. The author investigated a hypothesis that the instability arises from an interaction with a dense cloud of electrons accompanying the proton beam. He studied the phenomena experimentally by comparing the dynamics of stable and unstable beams, by numerically simulating the build-up of the electron cloud and its interaction with the beam, and by constructing an analytical model of an electron cloud-driven instability with the electrons trapped in combined-function dipole magnets. He has devised a method to stabilize the beam by a clearing bunch, which conclusively revealed that the instability is caused by the electron cloud, trapped in a strong magnetic field. Finally, he conducted measurements of the microwave propagation through a single dipole magnet. These measurements have confirmed the presence of the electron cloud in combined-function magnets.
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| Subject
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Electron-atom collisions.
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Particle beam instabilities.
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Electricity, electromagnetism magnetism.
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Electron-atom collisions.
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Mathematical physics.
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Particle high-energy physics.
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Particle beam instabilities.
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SCIENCE-- Physics-- Quantum Theory.
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| Subject
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Semi-conductors super-conductors.
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| Dewey Classification
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539.73
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| LC Classification
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QC793.3.B4
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