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Reconstruct the FEL x-ray profile with X-TCAV after undulator

Reconstruct the FEL x-ray profile with X-TCAV after undulator. Y. Ding, C. Behrens 3/18/2011. Thanks Zhirong and Paul for helpful discussions. Laser Heater Measurements. I nteraction between laser and electrons in wiggler leads to the increase of energy spread;

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Reconstruct the FEL x-ray profile with X-TCAV after undulator

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  1. Reconstruct the FEL x-ray profile with X-TCAV after undulator Y. Ding, C. Behrens 3/18/2011 Thanks Zhirong and Paul for helpful discussions.

  2. Laser Heater Measurements Interaction between laser and electrons in wiggler leads to the increase of energy spread; Use TCAV and dispersion to measure the longitudinal phase space, and know the heating effects. YAGS2 YAGS2 RF deflector ON time energy Laser OFF Laser: 40 µJ σE/E< 12 keV σE/E 45 keV

  3. FEL process leads to e-beam energy loss and energy spread increase We already have the E-loss scan GUI developed by P. Emma to measure the FEL radiation energy from electron beam energy loss. Total_E_loss = E_loss_FEL + E_loss_sr+E_loss_wake+… = E_loss_FEL + E_loss_FELoff Total_EnergySpread = sqrt(ES_FEL^2 + ES_sr^2+ES_wake^2+…) = sqrt(ES_FEL^2+ES_FELoff^2) If we use TCAV to measure the time-resolved e-beam energy loss or energy spread with FEL on and off, then we have the FEL radiation intensity profile. Of course, we also have e-beam distribution profile. • We show a few examples: • Hard x-ray ideal Gaussian beam rms = 7 um; • Hard x-ray ideal Gaussian beam rms = 1um; • Hard X-ray S2E real LCLS beam 3 kA case.

  4. Hard x-ray, Gaussian 7um rms, @ 70m FEL OFF FEL ON Und. exit Und. exit head OTRDMP OTRDMP head

  5. Hard x-ray, Gaussian 7um rms, @ 70m Reconstruct the x-ray profile with the time-resolved E-loss. Reconstruct the x-ray profile with the time-resolved energy spread (after arbitrary scaling).

  6. Hard x-ray, Gaussian 7um rms, @ 110m FEL OFF FEL ON Und. exit Und. exit head OTRDMP OTRDMP head

  7. Hard x-ray, Gaussian 7um rms, @ 110m Reconstruct the x-ray profile with the time-resolved E-loss. Reconstruct the x-ray profile with the time-resolved energy spread (after arbitrary scaling).

  8. Hard x-ray, Gaussian 1um rms, @ 70m FEL OFF FEL ON Und. exit Und. exit head OTRDMP OTRDMP head

  9. Hard x-ray, Gaussian 1um rms, @ 70m Reconstruct the x-ray profile with the time-resolved E-loss. Reconstruct the x-ray profile with the time-resolved energy spread (after arbitrary scaling).

  10. Hard x-ray, 250pC S2E LCLS beam Undulator entrance FEL power profile @ undu. exit

  11. Hard x-ray, 250pC S2E LCLS beam FEL OFF FEL ON Und. exit Und. exit head OTRDMP OTRDMP head

  12. Hard x-ray, 250pC S2E LCLS beam Reconstruct the x-ray profile with the time-resolved E-loss. Reconstruct the x-ray profile with the time-resolved energy spread (after arbitrary scaling).

  13. Discussions • A resolution of 1.5 fs to 3 fs may be achieved for e-beam measurements with X-TCAV; • At the same time, we can have the FEL x-ray profile. • Applicable for all radiation wavelength; • Wide diagnostic range, few fs to few hundred fs; • Profile, single shot; • No interruption with LCLS operation; • Both e-beam and x-ray. • Not cheap… • Slippage at soft x-ray…

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