Driver Accelerator Design

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The WBS 3 Talk

• Scope of work beam physics support for
• injector
• IR Demo analysis for upgrade guidance
• upgrade design and analysis (specification
  performance)
• system integration

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System Parameters (IRUV)
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Design Issues/Requirements

• Source/Injector Performance
• Delivery of appropriate beam to FEL beam quality
  preservation
• Beam internal self-interaction - space charge
• Beam external self-interaction - CSR
• Beam environmental interaction - wakefields, HOMs
• Machine Performance Energy Recovery
• Space charge, ions, BBU, FEL/RF interaction
• Geometric, schedule constraints
• Must meet cost schedule, fit in vault, avoid
  interference with Demo ops as long as possible

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WBS 3 Status

• IR Driver Design Revision 1.0 released
• design concept frozen
• details to be finalized (Revision 1.1)
• integrate final optical cavity design(s),
• resolve minor mechnical interferences perform
  parametric optimizations (improve chromatics by
  pushing quads around)
• change request for UV compatibility
• UV Driver Design Revision 1.0 ready for release
• UV Revision 1.1 to follow on heels of IR Revision
  1.1
• Machine performance/beam physics studies started

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Demo in Vault - Before
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Upgrade
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Upgrade Layout
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UV Integration
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Common Dipole Geometry

• Reduce bend field/angle, increase bend radius

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• Large dispersion slope requires dispersion
  management use final backleg dipoles run at half
  field to reduce angle, quads to dispersion
  suppress
• Requires slightly wider pole

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UV Compatibility Change Request

• Corner dipoles ? common dipoles
• Minor modification to rectangular dipole to
  utilize common design for IR chicane UV bypass
  reverse bends (IR Revision 1.1)

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Status Beam Physics Tasks
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Performance Analyses

• Starting beam/machine performance studies
• Longitudinal phase space management, octupole
  correction ultrashort bunches
• Accelerator error effects specifications
• HOM driven skew quad effects
• Alignment, magnet field quality/excitation
  errors, etc

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Longitudinal Phase Space Management

• Requirements
• short bunch (high peak current) at wiggler
• small momentum spread at dump

longitudinal phase space through acceleration
cycle
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Longitudinal Matching - cont.

longitudinal phase space during energy recovery
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Performance Analyses cont.

• Injector design performance, space charge
  (bunch internal self-interactions)
• CSR (bunch external self-interactions)
• BBU/HOM/other wakefield effects
  (beam/environmental interactions)
• RF system dynamics

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Upgrade Injector Design

• Space Charge analysis ongoing
• Support for gun design work (POISSON)

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CSR Analysis

• Ongoing refinement of model
• IR Rev 1.0 subjected to rudimentary check

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Beam/Environmental Interactions, RF System
Dynamics

• RF system issues
• 7-cell control module
• FEL/RF interaction analysis
• ion trapping
• BBU
• Thresholds
• TDBBU benchmarks
• HOM power dissipation
• other wakefield effects

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Publish or Perish

• PAC99
• L. Merminga, I. E. Campisi, D. Douglas, C.
  Hovater, G. A. Krafft,, B. C. Yunn, Beam Current
  Limitations in the Jefferson Lab FEL Simulations
  and Analysis of Proposed Beam Breakup
  Experiments,
• L. Merminga, I. Campisi, D. Douglas, B. Yunn,
  Beam Breakup Simulations for the Jefferson Lab
  FEL Upgrade
• R. Li, The Impact of Coherent Synchrotron
  Radiation on the Beam Transport of Short Bunches
• L. Merminga with the Jefferson Lab FEL Team,
  First Results on Energy Recovery in the
  Jefferson Lab IRFEL,
• FEL99
• R. Li, Improvement of the Self-Consistent CSR
  Simulation
• L. Merminga, P. Alexeev, S. Benson, L. Doolittle,
  G. Neil, FEL-RF Instabilities in Recirculating,
  Energy-Recovering Linacs with an FEL
• EPAC2000
• R. Li, Sensitivity of the CSR Self-Interaction
  to the Local Longitudinal Charge Concentration of
  an Electron Bunch

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Publish or Perish

• FEL2000
• L. Merminga and B. Yunn, Collective Effects in
  the Jefferson Lab FEL Upgrade
• R. Li, Sensitivity of the CSR Self-Interaction
  to the Local Longitudinal Charge Concentration of
  an Electron Bunch
• Linac2000
• R. Li, Analysis and Simulation on the
  Enhancement of CSR Effects
• L. Merminga, G. Krafft, C. Leemann, R. Sundelin,
  B. Yunn, J. Bisognano, Specifying HOM Power
  Extraction Efficiency In a High Average Current,
  Short Bunch Length SRF Environment
• D. Douglas, S. Benson, G. Krafft, R. Li, L.
  Merminga, B. Yunn, Driver Accelerator Design for
  the 10 kW Upgrade of the Jefferson Lab IR FEL
• APS Division of Plasma Physics Meeting
• R. Li, Bunch Self-interaction via Coherent
  Synchrotron Radiation Theory, Simulation, and
  Experiment
• PRL submissions
• R. Li, Sensitivity of the CSR Self-Interaction
  to the Local Longitudinal Charge Concentration of
  an Electron Bunch

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Publish or Perish

• JLab TNs
• CEBAF-TN-96-031 Design Considerations for the IR
  FEL Upgrade
• JLAB-TN-99-018 RF Requirements for the IRFEL
  Upgrade Project,''
• JLAB-TN-99-019 A Driver Accelerator for an FEL
  Upgrade
• JLAB-TN-99-020 FEL Upgrade Scenarios
• JLAB-TN-99-040 A 75 solution for the FEL
  Upgrade
• JLAB-TN-99-041 IR/UV FEL Upgrade Project
  Accelerator Physics Plan
• JLAB-TN-99-043 Aperture Considerations for the
  FEL Upgrade
• JLAB-TN-00-012 WBS 3.0 Beam Physics
  Requirements for IR Upgrade Driver Accelerator
• JLAB-TN-00-013 IR FEL Upgrade Driver Accelerator
  Design, Revision 1.0
• JLAB-TN-00-017 Preliminary Estimates of CSR
  Effects in the IR Upgrade FEL Driver
• JLAB-TN-00-020 Longitudinal Phase Space
  Management in the IR Upgrade FEL Driver

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Schedule
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