Suppression of Beam Breakup Instability in a Long Train by Introducing Energy Spread Between the Bunches PDF Download
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Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
Interaction between the bunches in the NLC main linac via long range wakefields can cause a beam breakup instability. Although the magnitude of the long range wakefields for an ideal NLC structure is below the instability threshold, the wake increases when structure manufacturing errors are taken into account. In case of large errors, the developing instability can result in the projected emittance dilution of the bunch train. To suppress the instability, the authors propose to introduce an energy spread between the bunches, similar to the BNS energy spread for damping of the beam breakup within a single bunch. Based on simple estimates, the authors show that the energy spread of order of 1--2% should be enough for suppression of the instability. The results of computer simulations with the simulation code LIAR confirm theoretical estimates and indicate that both the tolerances for structure misalignments and the incoming beam jitter can be considerably loosened by introducing the energy spread within the beam.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
Interaction between the bunches in the NLC main linac via long range wakefields can cause a beam breakup instability. Although the magnitude of the long range wakefields for an ideal NLC structure is below the instability threshold, the wake increases when structure manufacturing errors are taken into account. In case of large errors, the developing instability can result in the projected emittance dilution of the bunch train. To suppress the instability, the authors propose to introduce an energy spread between the bunches, similar to the BNS energy spread for damping of the beam breakup within a single bunch. Based on simple estimates, the authors show that the energy spread of order of 1--2% should be enough for suppression of the instability. The results of computer simulations with the simulation code LIAR confirm theoretical estimates and indicate that both the tolerances for structure misalignments and the incoming beam jitter can be considerably loosened by introducing the energy spread within the beam.
Author: Publisher: ISBN: Category : Languages : en Pages : 7
Book Description
It is shown herein that the energy spread of order one percent in the beam train in the NLC can suppress the emittance growth due to structure misalignments and initial jitter.
Author: Publisher: ISBN: Category : Languages : en Pages : 8
Book Description
The author studies BNS damping of the beam breakup instability in a simple model assuming a constant beam energy, flat bunch distribution, and a smooth transverse focusing. The model allows an analytic solution for a constant and linear wake functions. Scaling dimensionless parameters are derived and the beam dynamics is illustrated for the range of parameters relevant to the Stanford Linear Collider.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
Beam Breakup (BBU) occurs in all accelerators at sufficiently high currents. In recirculating accelerators, such as the energy recovery linacs used for high power FELs, the maximum current has historically been limited by multipass, multibunch BBU, a form that occurs when the electron beam interacts with the higher-order modes (HOMs) of an accelerating cavity on one pass and then again on the second pass. This effect is of particular concern in the designs of modern high average current energy recovery accelerators utilizing superconducting technology. In such two pass machines rotation of the betatron planes by 90a, first proposed by Smith and Rand in 1980 [1], should significantly increase the threshold current of the multibunch BBU. Using a newly developed two-dimensional tracking code, we study the effect of optical suppression techniques on the threshold current of the JLAB FEL Upgrade. We examine several optical rotator schemes and evaluate their performance in terms of the instability threshold current increase.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
The SLAC design for a next-generation linear collider with center-of-mass energy of 0.5 to 1.0 TeV requires that multiple bunches ((approximately)10) be accelerated on each rf fill. At the beam intensity ((approximately)101° particles per bunch) and rf frequency (11--17 GHz) required, the beam would be highly unstable transversely. Using computer simulation and analytic models, we have studied several possible methods of controlling the transverse instability: using damped cavities to damp the transverse dipole modes; adjusting the frequency of the dominant transverse mode relative to the rf frequency, so that bunches are placed near zero crossings of the wake; introducing a cell-to-cell spread in the transverse dipole mode frequencies; and introducing a bunch-to-bunch variation in the transverse focusing. The best cure(s) to use depend on the bunch spacing, intensity, and other features of the final design. 8 refs., 3 figs.
Author: William Lou Publisher: ISBN: Category : Languages : en Pages : 122
Book Description
The construction of Cornell BNL Energy-Recovery-Linac Test Accelerator (CBETA) was completed at Cornell University's Wilson Laboratory in 2019. CBETA is designed to accelerate electrons from 6 MeV to 150 MeV in four linac passes using a single Fixed Field Alternating gradient (FFA) return beamline accepting all energies from 42 to 150 MeV. Energy recovery is achieved by decelerating the beam within the Superconducting Radio Frequency (SRF) cavities, in which the beam returns energy to the electromagnetic field. Energy recovery allows CBETA to produce a beam current much higher than with conventional storage rings. This thesis focuses on two important limits of CBETA: the beam current limit due to Beam Breakup (BBU) instability and the bunch charge limit due to Coherent Synchrotron Radiation (CSR) effects. For BBU, elementary theories are revisited to benchmark the simulation codes. Additional theory regarding the scaling law of the threshold current and the effect of chromaticity are also investigated. For CSR, a new "2-bend" theory has been developed by extending the conventional 1-bend theory using the Lienard-Wiechert formula. The new theory is essential to describe CSR wake propagation when magnets are located close to each other, as in CBETA. These new theories could benefit designs and researches of future ERLs. For both topics, extensive simulations have been performed using the software developed by Cornell University, Bmad.
Author: Alexander Wu Chao Publisher: Wiley-VCH ISBN: 9780471551843 Category : Science Languages : en Pages : 384
Book Description
Draws attention to important theoretical and mathematical aspects of beam instabilities. Introduces and analyzes various collective instability effects for high energy accelerators. Uses a significant amount of models and soluble examples as illustrations.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
We investigate a method to control the multipass dipole beam breakup instability in a recirculating linac including energy recovery. Effectiveness of an external feedback system for such a goal is shown clearly in a simplified model. We also verify the theoretical result with a simulation study.
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Author: Sergei Glukhov
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Author: Peter Richard Menge
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Author: William Lou
Author: Alexander Wu Chao
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