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.