0. Commissioning of the Aramis undulator line @ 3GeV
FLAC XV
Commissioning of the Aramis undulator 3GeV
Marco Calvi
February 2, 2015, Villigen PSI

1. Overview Preparatory work at the MML BBA to define the reference orbit
Commissioning with electron beam
Alignment of the undulator modules
Correction of the residual U15 field errors
Commissioning with photon beam
Fine-adjustment of the height and pitch
In situ calibration of the individual K-values
Pointing direction: checks and corrections
Setting up of the phase shifters
FEL signal characterization
Pulse energy (absolute) and its statistic
Gain length per module
Conclusions

2. Preparatory work @ MML U15 Phase Shifter Alignment Quadrupoles
Optimization of the trajectory and phase of the U15s
Calibration of the K versus gap: gn(K)
Measurements of the residual 1st and 2nd field integrals versus K: I1n(K) & I2n(K)  inδn(K) & outδn(K)
Phase Shifter
Optimization of the field integrals
Phase shift versus gap calibration: gn(ϕ)
Alignment Quadrupoles
Check the Gdl and the reproducibility of the transversal positioning
Magnetic alignment on the U15 axis

3. Phase shifter

4. Alignment Quadrupoles

5. Aramis Beam Based Alignment
Corrector-based BPM alignment (Aiba & Böge FEL 2012)
Procedure
Steer the beam to the centres of BPMs and record the corresponding corrector strengths (strong correction indicates large misalignments)
Find BPM positions that minimise the deviation of corrector strengths
Corrector strengths will be all zero if no misalignments and no error field
A running orbit feedback simplify the above procedure
Features
Random error field dependent (undulator error fields must be small)
No momentum change is required and thus quick
Corrector strengths must be the same value for periodic line

6. Overview Preparatory work at the MML
Run BBA to define the reference orbit
Commissioning with electron beam
Alignment of the undulator modules
Correction of the residual U15 field errors
Commissioning with photon beam
Fine-adjustment of the height and pitch
In situ calibration of the individual K-values
Pointing direction: checks and corrections
Setting up of the phase shifters
FEL signal characterization
Pulse energy (absolute) and its statistic
Gain length per module
Conclusions

7. Undulator alignment

8. Undulator alignment

9. Undulator alignment

10. Undulator alignment
The upstream & the downstream alignment quadrupoles can be used independently to define the x & y positions at the two extremes
Later the x , y , pitch & yaw position of the U15 module can be calculated and the undulator moved to the new position
Finally the alignment quadrupole can still be used to check and to verify the stability with time

11. Field Error Corrections

12. Field Error Corrections

13. Field Error Corrections

14. Overview Preparatory work at the MML
Run BBA to define the reference orbit
Commissioning with electron beam
Alignment of the undulator modules
Correction of the residual U15 field errors
Commissioning with photon beam
Fine-adjustment of the height and pitch
In situ calibration of the individual K-values
Pointing direction: checks and corrections
Setting up of the phase shifters
FEL signal characterization
Pulse energy (absolute) and its statistic
Gain length per module
Conclusions

15. Photon diagnostic Front end slits for shaping the white beam
Double crystal monochromator ( keV) with a bandwidth of about 10-4
Photo diode for pulse energy
MCP for low intensity pulse and profile monitor

16. Height and pitch adjustment
T.Tanaka et al. Phys. Rev. ST Accel. Beams 15, 2012
Set all undulator at open gap
Set the undulator n at K=1.2
Set the monochromator at E(K)
Move the undulator height around the nominal position and measure the photon flux
K=K0+αh2
The axis is defined by the magnetic field symmetry
If the g(K) relation is correct the axis has also the highest photon flux

17. g(K) value calibration
T.Tanaka et al. Phys. Rev. ST Accel. Beams 15, 2012
Set all undulator at open gap
Set the module n at K
and the monochromator at E(K)
Move the undulator gap around the nominal value while recording the photon flux
When the blue edge of the spectrum is well characterized the actual gap shall be extracted using empirical fits

18. g(K) value calibration

19. Photon pointing direction
T.Tanaka et al. Phys. Rev. ST Accel. Beams 15, 2012
Set all undulator at a given K value
Shift the module n to K+ΔK
and set the monochromator at the energy E(K+ΔK)
Use MCP+FS respectively to amplify and detect the profile of the pulse on a CCD
This procedure shall be repeated for all modules (and eventually also for different K)
The steering magnets shal be tuned to improve the overlap of the different sources

20. Setting the Phase Shifters
T.Tanaka et al. Phys. Rev. ST Accel. Beams 15, 2012
Set all undulator at open gap
Close the modules n and n+1 at K
Set the monochromator at the energy E(K)
Change the phase shift between from maximum to minimum
This procedure shall be repeated for all phase shifter modules (and eventually also for few different K)

21. Overview Preparatory work at the MML
Run BBA to define the reference orbit
Commissioning with electron beam
Alignment of the undulator modules
Correction of the residual U15 field errors
Commissioning with photon beam
Fine-adjustment of the height and pitch
In situ calibration of the individual K-values
Pointing direction: checks and corrections
Setting up of the phase shifters
FEL signal characterization
Pulse energy (absolute) and its statistic
Gain length per module
Conclusions

22. Pulse energy
Courtesy of E.Prat
All undulator set at a given K value (eventually with a taper)
Record the pulse energy on a single slot base
Build up the statistic:
Average pulse energy (mJ)
Number of excited modes

23. D.Ratner, Proceedings of the FEL2009, Liverpool, UK
Gain Length
D.Ratner, Proceedings of the FEL2009, Liverpool, UK
Set all undulator at open gap
Close the first module to K and record the average photon flux
Close also the second to K and record the average photon flux ….
Repeat until all the modules are closed to K

24. Conclusions
The general ideas for the commissioning of the Aramis undulator line have been presented
A preliminary procedure has been internally discussed among different groups
and the hardware as well as the timing have been verified
In the coming months a more detailed procedure shall be written down and finally approved

25. Thanks for your attention!