4GLS High Average Current Injector

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4GLS High Average Current Injector

• Julian McKenzie
• ASTeC
• Cockcroft Institute All Hands Meeting
• 30th March 2007

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4GLS High Average Current Loop
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Required Injector Parameters
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Injector Options
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Overview

• 500kV DC gun with GaAs type photocathode
• Two focussing solenoids
• Normal conducting buncher
• Two 5 MeV superconducting accelerating modules

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Superfish simulation of 500kV photocathode gun

• 6mm laser spot diameter
• 12mm diameter GaAs wafer
• 10 sloped focusing cathode
• 14cm to anode
• 500kV, max field on axis 3.5MV/m
• Max field strength on electrodes 5MV/m

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Normal Conducting Buncher Cavity
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SRF Accelerating Module

• Five 2-cell cavities per module

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Astra simulations

• Initial beam parameters
• 6mm diameter top-hat transverse profile
• 20ps rms Gaussian longitudinal distribution
• 0.94pmmmrad initial thermal emittance
• 1000 macroparticles

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Beam dynamics up to the booster
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Beam dynamics
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Final particle distribution
Transverse
Longitudinal
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Future Work

• Final optimisation of injector parameters to meet
  specification
• Design and beam dynamic simulations of the beam
  merger
• 3D electro-static simulation of gun with
  off-centre wafer position
• 3D beam dynamic simulations with GPT code