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ERL Conference at Daresbury Talk by P. J Phillips

Single Shot Longitudinal bunch profile measurements by temporally resolved electro-optical detection. ERL Conference at Daresbury Talk by P. J Phillips. Goal. Develop non-destructive sub-picosecond longitudinal Bunch Profile diagnostic. Electro-optic detection of bunch Coulomb field

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ERL Conference at Daresbury Talk by P. J Phillips

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  1. Single Shot Longitudinal bunch profile measurements by temporally resolved electro-optical detection ERL Conference at Daresbury Talk by P. J Phillips

  2. Goal Develop non-destructive sub-picosecond longitudinal Bunch Profile diagnostic Electro-optic detection of bunch Coulomb field Dundee University / STFC ASTeC / FOM Instituut “Rijnhuizen” / DESY / University of Abertay

  3. Ideal diagnostic?Non-intrusiveNon-destructive Single shotReal time diagnostic

  4. Electro-optic longitudinal bunch profile measurements convert bunch Coulomb field into optical intensity variation. probe laser co-propagates with bunch (with transverse offset) decoding of information from laser pulse Effective polarisation rotation proportional to coulomb field encoding of bunch information into laser

  5. Temporal Decoding • the chirped laser pulse behind the EO crystal is measured by a short laser pulse with a single shot cross correlation technique

  6. Encoding Time Resolution... material response, IG(f)I • velocity mismatch of Coulomb field and probe laser • frequency mixing efficiency [c (2)(w)]

  7. e-bunch at 450 MeV 1000 pC < 100 fs spike At 32 nm Experimental setup at FLASH (Free electron LASer at Hamburg) • 4 nJ, 15 fs Ti:Sa Oscillator • 1 mJ, 35 fs Ti:Sa Amplifier • ZnTe (185 mm) • GaP (65 mm) Used in these experiments

  8. Laser Hutch at FLASH

  9. Setup in the FLASH tunnel

  10. Temporal Decoding

  11. Time Calibration.... probe laser gate laser bunch

  12. Benchmarking EO by LOLA 450 MeV, 1nC~20% charge in main peak

  13. EO and LOLA results... Electro-optic bunch profile Transverse Deflecting Cavity bunch profile (LOLA)

  14. Current data taken at FLASH Data taken with GaP (65 um) Q=0.65 nC, r = 3.8 mm The measured retardation Measured LOLA signal Calculated electric field Simulated EO signal / phase retardation Simulation by B. Steffen

  15. Can we get shorter resolution • Lola measurement Actual bunch profile ( ~60 fs resolution) • Coulomb angle 1/g ~ 50 fs for g ~1000 • Material • GaP • New material ( Phase matching, c2 considerations) • Gate pulse width ~ 50 fs • Introduce shorter pulse • Spectral interferometry • FROG Measurement

  16. Electro-optic encoding section on ERLP.... encoding = bunch profile into optical pulse probe laser bunch to laser diagnostic decoding(optical pulse into profile measurement)

  17. Robust and reduced footprint EO measurement system Installed at FLASH Also to used at Energy Recovery Linac Prototype (ERLP) Daresbury Future

  18. Electro-optic detection of single electron bunches with FWHM of 118 fs Response of electro-optic material is the temporal limitation in these experiments Simultaneous TDC and electro-optic measurements show good agreement in the shapes of electron bunch profile Non-invasive property of the electro-optic measurement allowed it to be used as a diagnostic tool during SASE operation Conclusions

  19. G. Berden Lex van de Meer W.A. Gillespie B. Steffen E.-A. Knabbe H. Schlarb B. Schmidt P. Schmüser S. P. Jamison A.M Macleod

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