Accelerator Commissioning

• FEL Requires Excellent Beam
  • Commissioning starts with design
  • Written test plan to guide commissioning
  • Written procedures for specific system startup
  • Calculated nominal magnet field strengths and rf gradients in Restorable file
  • Commissioning is incremental so SAVE/RESTORE function is essential

Test Systems without Safety Constraints

• Test all systems as soon as possible
  • magnets
  • optical diagnostic controls
  • plant services
  • low level rf controls
  • vacuum
  • diagnostics
  • CHL
  • machine protection system
  • Save/Restore function

Test Systems With Safety Constraints

• electron gun high voltage
  • high voltage feed cabling
  • interlocks
  • re-process cathode structures
• high power laser
  • verify laser power output
  • connect laser rf with master oscillator
  • alignment of optical system
• high power rf
  • SRF commissioning
  • verify downloads to low level controllers
  • fine tune loop controllers
  • verify software
• high power dipole magnets

Accelerator Commissioning

• Initial setup to Straight ahead dump
  • Injector Beam Parameters Verified
  • Match Beam into Cryomodule
  • Thread through Cryomodule
  • Transient Phasing of Module
  • Thread beam to 10/42 MeV dump
  • Fine phasing of rf cavities
  • Thread beam to straight ahead dump

Beam Verification Steps

• Use beam diagnostics to verify model
  • Setup/Verify beam loss monitoring (BLM) system
  • Verify apertures match model using BLM's
  • Verify emittance and dp/p in front of the wiggler
  • Verify Gradient/phase setpoints of rf against phase space diagnostic at low and high currents
• Match the beam into the wiggler

Setup beam through the wiggler

• Get beam with best chance of lasing
  • Align beam through chicanes
  • Scan for apertures through wiggler region using low power beam
  • Check operation of OTR in exit chicane at 600 uA
• Switch to Wiggler Lasing procedure

After First Light

• Commission rest of Transport line
  • Power arc dipoles
  • Thread through arc 1; Test emittance growth through arcs
  • Use synchrotron light monitors to place the beam in the dipoles
  • Thread the beam down the backleg of the machine
  • Perform beam properties measurement with OTR's
  • Thread through arc 2 / Center the beam in dipoles

Prepare to Recirculate Beam

• Commission BLM system in arcs and return line
• Perform beam properties measurement
• Set matching quads to recirculate
• Measure M5,6 from exit of wiggler to entrance of cryomodule
• Verify BLM and rf systems

Recirculate Beam

• Inject pulsed, recirculated beam into the cryomodule and determine the phase from the transient signal
• Calibrate arrival time diagnostic against known pathlength changes in arcs
• Adjust the pathlength using the arcs to perform energy recovery
• Thread recirculated beam to 10 MeV dump

Lase at high current

• Retune the wiggler to lase
• Set up low current, recirculated, beam
• Lase, using the lasing procedure to determine the point on the extraction curve. Monitor the dp/p in the arcs and change in arrival time at M5,6 monitor closely.
• Ramp up the current to 5 mA in ~100 msec.