1. Status of DESY-PSI-CERN collaboration on development of X-band TDS with variable polarisation: PolariX-TDS
Alexej Grudiev on behalf of Polarix-TDS collaboration
CLIC project meeting, 7/05/2019, CERN
07/05/2019
A. Grudiev

2. Acknowledgements
To all the people whose slides I have used in my presentation
7/05/2019
A. Grudiev

3. Outline
Introduction on the applications of high-gradient X-band structures
X-band structures for longitudinal phase space manipulations (linearizers)
X-band transverse deflecting structures
PolariX-TDS collaboration status
Timeline
Status at DESY and PSI
First prototype fabrication and RF measurement at PSI
First prototype high power tests at CERN
Outlook
07/05/2019
A. Grudiev

4. FERMI X-band linearizer
Linearizers are essential for FEL operation
X-band linearizers are in routine operation for many years at
LCLS,
FERMI,
SwissFEL
New are planned
CLARA
Shanghai …
Linearizer is there to remove RF curvature present in the longitudinal phase space of the bunch before compression.
Effect is proportional to second derivative of the RF voltage => ~(f/f0)2
X-band has clear advantage
X-band linearizer
GdA_CLIC Workshop 2014

5. Transverse Deflecting Structures for Longitudinal and Transverse Diagnostics
Measurement of the energy spread induced by the FEL process at SLAC
Achieved temporal Resolution < 1fs for soft X-rays
X-band RF deflector is in operation at LCLS for several years
Versatile tool for longitudinal and transverse beam diagnostic
Streak is proportional to 1st derivative of the RF voltage => ~f
X-band is better than S- or C-band
The paper published at SLAC in 2014 still constitutes the state of the art for high resolution longitudinal phase-space measurement of e-bunches in linacs.
Describe experiment – TDS streaks in horizontal direction
Comment on resolution
C. Behrens et al., „Few-femtosecond time-resolved measurements of X-ray free electron laser“ , Nat. Comm (2014).

6. Potential applications of the variable polarization TDS
Next generation TDS
Exciting new opportunities for e-bunch characterization (e.g. slice emittance measurement on different planes, tomography …)
It is planned to build few next generation TDS in Europe:
For FELs:
FLASH2
SwissFEL
And for AAC test facilities:
FLASHforward
SINBAD
3D reconstruction of the charge distribution
Identify correlations, tilts of the beam distribution in 3D
Measurement screen
e-beam
TDS
What can the previous feature be used for?
We can streak the beam in all transverse directions
Characterizing the correlations of the transverse properties of the beam with z, 3D mapping
Variable direction streaking field

7. X-band TDS with variable polarizationVP KL DC PC WG
E-Hybrid
Variable Phase Shifter
TDS
RF Loads
E-Rotator
Vacuum pumping port
Phase difference between port 1 and port 2:
0 degree -> vertical polarization
180 degree -> horizontal polarization
A. Grudiev, CLIC-note-1067 (2016).
07/06/2019
A. Grudiev

8. Polarix-TDS collaboration time line
PolariX-TDS collaboration is a collaboration between DESY, PSI and CERN on the development of variable Polarization X-band Transverse Deflecting Structures and associated RF systems for application at PSI and DESY
February 2016 – first contact DESY-CERN
May 2016 – PSI joins DESY and CERN and collaboration is formed
September 21st, 2016 – First Collaboration meeting at DESY
October 27th, 2017 – First Collaboration Review meeting at PSI
PolariX-TDS design
February, 2018 – Formal DESY-PSI-CERN collaboration agreement has been signed
February 20th, 2019 – Second Collaboration Review meeting at CERN
Fabrication and RF measurements of the first Prototype
07/05/2019
A. Grudiev

9. PolariX-TDS at DESY
07/05/2019
A. Grudiev

10. PolariX-TDS at DESY
07/05/2019
A. Grudiev

11. PolariX-TDS at PSI
07/05/2019
A. Grudiev

12. PolariX-TDS fabrication at PSI
Excellent results on the shape accuracy
07/05/2019
A. Grudiev

13. PolariX-TDS fabrication at PSI
07/05/2019
A. Grudiev

14. PolariX-TDS RF measurements at PSI
Excellent results of the RF measurements
07/05/2019
A. Grudiev

15. PolariX-TDS high-power testing at CERN
07/05/2019
A. Grudiev

16. PolariX-TDS high-power testing at CERN
End of February 2019, PolariX-TDS Prototype N1 has been installed in Xbox2
It has been conditioned up to 25 MW input power at 100ns pulse within few weeks
End of April, 2019, High power testing has been stopped
1st week of May (last week), Prototype has been dismounted and made ready for shipment to DESY
07/05/2019
A. Grudiev

17. PolariX-TDS prototype N1 at DESY
Yesterday Polarix-TDS N1 has arrived to DESY
It is planned to install it to FLASHforward beam line in the summer shutdown (July 2019)
First beam tests are planned towards October 2019
07/05/2019
A. Grudiev

18. PolariX-TDS Outlook By mid 2020
4 more PolariX-TDS are planned to be build for DESY: 2 for FLASH2 and 2 for SINBAD
AND
2 more PolariX-TDS for PSI for SwissFEL ATHOS post undulator line
It is not only TDSs but also high power X-band RF systems which are under construction:
2 at DESY
1 additional (to existing one for linearizer) at PSI
07/05/2019
A. Grudiev