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Seeded jitter studies

Seeded jitter studies. Z. Huang, et al., November 7, 2012. Seeding MD (May 15). 150 pC , SASE vs. Seeded after Kmono E-beam energy 13.64 GeV , photon energy 8.3 keV Bragg angle 57.875 deg for 004 seeding (accurate to 0.001 deg) Kmono bandwidth ~1 eV

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Seeded jitter studies

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  1. Seeded jitter studies Z. Huang, et al., November 7, 2012

  2. Seeding MD (May 15) • 150 pC, SASE vs. Seeded after Kmono • E-beam energy 13.64 GeV, photon energy 8.3 keV • Bragg angle 57.875 deg for 004 seeding (accurate to 0.001 deg) • Kmono bandwidth ~1 eV • Tune on Kmono diode signal not on gas detector  BC2 Ipk=2 kA, L1S=-24.5 deg, L1X=-160 deg, U1-2 out • Gas detector shows 0.5 mJ SASE, and seeded peaks at 1 mJ

  3. Seeded jitter sensitivity studies with Kmono Seeded intensity vs. linac energy (rms energy jitter 5e-4) average 6.8 (rms intensity jitter 72%) average 11.5 (rms intensity jitter 22%) Filter out energy jitter

  4. Seeded jitter sensitivity studies with Kmono Seeded intensity vs. linac energy (rms energy jitter 5e-4) average 6.8 (rms intensity jitter 72%) average 10.9 (rms intensity jitter 25%) Reduce energy jitter to 1.8e-4

  5. 1D FEL Simulation FEL parameter ρ= 5 x 10 -4 A. Lutman Electron beam at undulator entrance Flat current and electron energy profile Random electron beam central energy with Gaussian Distribution energy Uncorrelated energy spread with average = 0.6 ρ rms= 0.1 ρ Uncorrelated energy spread central energy Seed Laser Flat seed laser profile phase Intensity distributed as negative exponential with average 5 MW

  6. Electron Beam energy vsIntensity (7 x 10-4relative energy rms) Total Intensity 2 gl after saturation 2 gl before saturation 4 gl after saturation Intensity in 1 eV 2 gl after saturation 2 gl before saturation 4 gl after saturation

  7. Amplification Bandwidth and Fluctuations, comparison with experimental data Experimental Data Kmono measurement 05/15/2012 Simulated Data 2 gain lengths after saturation Without taper Relative energy rms 7 x 10-4 Relative energy rms7.2 x 10-4 Fluctuations (1eV) 70% Fluctuations 72% Relative amplification bandwidth (fit rms) 3.5 x 10-4 (relative energy) Relative amplification bandwidth (fit rms) 3.5 x 10-4 (relative energy)

  8. (111) Seeding at 5.5 keV (004) J. Hastings (111) 2.0 35.26 (220) Diamond seed beam With input beam perpendicular to the Crystal the photon energy for the (111) is 5.21 keV

  9. Undulator taper at 5.5 keV Taper response Maximum FEL intensity (>400 uJ) responses well to strong undulator taper 40 pCbunch length < 10 fs, maximum peak power > 40 GW

  10. Comparison of taper result on-energy shots J. Wu experiment simulation off-energy shots Simulation for energy jitter: blue (on-energy), black (+0.1 %), red ( -0.1 % ), magenta (-0.2 %)

  11. Summary • Seeded FEL power is very sensitive to linacenergyjitters. • Need to improve energy jitters to < 2e-4 (rms). • Seeded FEL responses to energy jitter and undulator taper appear to agree with simulations, but the relevant data set is small.

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