Emittance Exchange (EEX)

1. Emittance Exchange (EEX) I. Chaikovska, F. Fu, T. Grandsaert, A. Lueangaramwong, K. Poor Rezaei

2. Motivation • X-ray FELs demand ultra-low transverse emittancebeam† • State-of-the art photo-injectors cannot generate low 6-D emittance. Emittance exchange can, using TM110 mode of RF cavities instead of absorbers combining with dipole chicanes to exchange transverse emittance (too large) to longitudinal emittance (too small). • Can also be used to suppress microbunchinginstability‡ † P. Emma et al. , Nature Photonics 4, 641 - 647 (2010) ; ‡ M. Cornacchia and P. Emma, PRSTAB 5, 084001 (2002)

3. Emittance Exchange Beamline Dogleg 1 Dogleg 2 RF Cavity J. C. T. Thangaraj, “Experimental studies on an emittanceexchange beamline at the A0 photoinjector”, Fermi National Accelerator Laboratory, Batavia, Illinois

4. Dogleg T. Koeth, “An Observation of a Transverse to Longitudinal Emittance Exchange at the Fermilab A0 Photoinjector”, Rutgers, New Jersey

5. TM110 Mode Cavity • Trajectories of an electron at different phases through the TM110 Mode Cavity • Depicts the peak εzfield in the horizontal plane • Depicts the peak vertical magnetic field which occurs 90◦ later in time. T. Koeth, “An Observation of a Transverse to Longitudinal Emittance Exchange at the Fermilab A0 Photoinjector”, Rutgers, New Jersey

6. TM110 Mode Cavity T. Koeth, “An Observation of a Transverse to Longitudinal Emittance Exchange at the Fermilab A0 Photoinjector”, Rutgers, New Jersey

7. Emittance Exchange Beamline J. C. T. Thangaraj, “Experimental studies on an emittanceexchange beamline at the A0 photoinjector”, Fermi National Accelerator Laboratory, Batavia, Illinois

8. Emittance Exchange Beamline 1 εx, in = 4.7 um εz, in = 21.1 um J. C. T. Thangaraj, “Experimental studies on an emittanceexchange beamline at the A0 photoinjector”, Fermi National Accelerator Laboratory, Batavia, Illinois

9. Emittance Exchange Beamline 2 εx, in = 4.7 um εz, in = 21.1 um J. C. T. Thangaraj, “Experimental studies on an emittanceexchange beamline at the A0 photoinjector”, Fermi National Accelerator Laboratory, Batavia, Illinois

10. Emittance Exchange Beamline 3 εx, in = 4.7 um εz, in = 21.1 um J. C. T. Thangaraj, “Experimental studies on an emittanceexchange beamline at the A0 photoinjector”, Fermi National Accelerator Laboratory, Batavia, Illinois

11. Emittance Exchange Beamline 4 εx, in = 4.7 um εz, in = 21.1 um J. C. T. Thangaraj, “Experimental studies on an emittanceexchange beamline at the A0 photoinjector”, Fermi National Accelerator Laboratory, Batavia, Illinois

12. Emittance Exchange Beamline 5 εx, in = 4.7 um εz, in = 21.1 um J. C. T. Thangaraj, “Experimental studies on an emittanceexchange beamline at the A0 photoinjector”, Fermi National Accelerator Laboratory, Batavia, Illinois

13. Emittance Exchange Beamline εx, out = 21.1 um εz, out = 4.7 um 6 εx, in = 4.7 um εz, in = 21.1 um J. C. T. Thangaraj, “Experimental studies on an emittanceexchange beamline at the A0 photoinjector”, Fermi National Accelerator Laboratory, Batavia, Illinois

14. Three Schemes for EEX Xiang, Dao, and Alex Chao. "Emittance and phase space exchange for advancedbeam manipulation and diagnostics." PhysicalReviewSpecialTopics-Accelerators and Beams 14.11 (2011): 114001.

15. Three Schemes for EEX ≠ 0 Limitation: Thick-lens effect High Energy Particle ≠ 0 Xiang, Dao, and Alex Chao. "Emittance and phase space exchange for advancedbeam manipulation and diagnostics." PhysicalReviewSpecialTopics-Accelerators and Beams 14.11 (2011): 114001.

16. Three Schemes for EEX Limitation: Thick-lens effect High Energy Particle Xiang, Dao, and Alex Chao. "Emittance and phase space exchange for advancedbeam manipulation and diagnostics." PhysicalReviewSpecialTopics-Accelerators and Beams 14.11 (2011): 114001.

17. First Observation of EEX J. Ruan., et al. "First observation of the exchange of transverse and longitudinal emittances." FERMILAB-PUB-10-468-AD (2011).

18. First Observation of EEX {εx, εy, εz } = {2.9 ± 0.1, 2.4 ± 0.1, 13.1 ± 1.3} ⇒ {11.3 ± 1.1, 2.9 ± 0.5, 3.1 ± 0.3} mm-mrad. J. Ruan., et al. "First observation of the exchange of transverse and longitudinal emittances." FERMILAB-PUB-10-468-AD (2011).

19. Applications: High Gain FEL Neil Thompson., et al. "The 4GLS VUV-FEL." University of Strathclyde (2011).

20. Applications: High Gain FEL Neil Thompson., et al. "The 4GLS VUV-FEL." University of Strathclyde (2011).

21. Applications: THz Generation Conversion of the transverse modulations to longitudinal modulations : beam shaping application.

22. Applications: THz Generation Conversion of the transverse modulations to longitudinal modulations : beam shaping application. Sun, Y. E., Piot, P., Johnson, A., Lumpkin, A. H., Maxwell, T. J., Ruan, J., & Thurman-Keup, R. (2010). Tunablesubpicosecondelectron-bunch-train generationusing a transverse-to-longitudinal phase-space exchange technique. Physicalreviewletters, 105(23), 234801.

23. TM110 Mode Cavity Cross sectional view of the TM110Mode Cavity with lN2jacket The fully brazed TM110 Mode Cavity without its liquid nitrogen jacket T. Koeth, “An Observation of a Transverse to Longitudinal Emittance Exchange at the Fermilab A0 Photoinjector”, Rutgers, New Jersey

24. Limitations • Timing and energy jitter: X-ray pointing stability • EEX is expensive due to RF and thermal considerations • Modern photoinjectors produce low emittance beam (no need for EEX)

25. Acknowledgments • Timothy Maxwell • Stanford • SLAC • SSSEPB Organizers/Students