MaRIE. MaRIE X-Ray Free-Electron Laser Pre-Conceptual Design

Transcription

1 Operated by Los Alamos National Security, LLC, for the U.S. Department of Energy MaRIE (Matter-Radiation Interactions in Extremes) MaRIE X-Ray Free-Electron Laser Pre-Conceptual Design B. Carlsten, C. Barnes, K. Bishofberger, L. Duffy, C. Heath, Q. Marksteiner, D. Nguyen, S. Russell, R. Sheffield, E. Simakov and N. Yampolsky LANL R. Ryne LBNL

2 MaRIE builds on the LANSCE facility to provide unique experimental tools to meet this need First x-ray scattering capability at high energy and high repetition frequency with simultaneous charged particle dynamic imaging (MPDH: Multi-Probe Diagnostic Hall) Unique in-situ diagnostics and irradiation environments beyond best planned facilities (F 3 : Fission and Fusion Materials Facility) Comprehensive, integrated resource for materials synthesis and control, with national security infrastructure (M4: Making, Measuring & Modeling Materials Facility) Accelerator Systems Electron Linac w/xfel LANSCE proton accelerator power upgrade Experimental Facilities Conventional Facilities MaRIE will provide unprecedented international user resources Slide

3 MaRIE photon needs can be met by an XFEL that is technically feasible and affordable MPDH FFF M4 Energy/Range (kev) 5 < - > Photons per image 9 9 Time scale for single image 5 fs > s. s -5 fs 5 fs Energy Bandwidth ( E/E) Beam divergence µrad µrad < µrad < µrad µrad Trans. coherence (TC) or spatial res. TC TC - µm TC TC Single pulse # of images/duration /.5 µs Multiple pulse rep. rate/duration Hz/day. Hz/mo. 6 Hz/secs KHz/day Hz/days Longitudinal coherence yes yes no yes yes Polarization linear linear no Linear/circular linear Tunability in energy ( E/E/time) %/pulse fixed fixed %/s x/day Photon energy - set by gr/cm of sample and atomic number Photon number for an image - typically set by signal to noise in detector and size of detector Time scale for an image - fundamentally breaks down to transient phenomena, less than ps, and semi-steady state phenomena, seconds to months Bandwidth - set by resolution requirements in diffraction and/or imaging Beam divergence - set by photon number loss due to stand-off of source/detector or resolution loss in diffraction Source transverse size/transverse coherence - the source spot size will set the transverse spatial resolution, if transversely coherent then this limitation is not applicable so transverse coherence can be traded off with source spot size and photon number Number of images/rep rate/duration images needed for single shot experiments/image rep rate/ duration of experiment on sample Repetition rate - how often full images are required Longitudinal coherence 3D imaging Polarization - required for some measurements Tunability time required to change the photon energy a fixed percentage

4 XFEL Beam Energy Must GeV or Less, With Tiny Emittances Beam energy is typically chosen because of two constraints: ε beam γ = ε lab λ x ray 4 = λ wiggler 8γ ( K + ) The choice for beam energy (γ) is dominated by the beam emittance, not wiggler period (which can go down to cm) Energy diffusion limits how high the beam energy can be (~ GeV), puts a very extreme condition on the beam emittance (ideally ~.5 µm) d dz 55e γ rb δ = QF 4 3mc ( E ) 4 3 e w e Slide 4

5 Reasonable Baseline Design pc, Extension of LCLS S-band photoinjector S-band accelerator to MeV First bunch compressor S/X-band accelerator to GeV Second bunch compressor GeV beam S/X-band accelerator to GeV 7 GW, ~ 4 X-rays ~ -3 spectral bandwidth XFEL undulator - resonant at ¼ Å pc, 3 fsec, 3.4 ka,.5% energy spread.3 µm emittance Slide 5

6 The Baseline MaRIE XFEL is a Reasonable Extrapolation of Demonstrated LCLS Performance UNIT LCLS MARIE baseline Wavelength Å.5.48 Beam energy GeV Bunch charge pc 5* (5) Pulse length (FWHM) fs 8* 3 Peak current ka 3.* 3.4 Normalized rms emittance mm-mrad (.5) Energy spread %..5 Undulator period cm 3.4 Peak magnetic field T.5.93 Undulator parameter, a w Gain length, D (3D) m (3.3)* 5.7 (6.4) Saturation length m Peak power at fundamental GW 3* 3 Pulse energy mj.5*.48 # of photons at fundamental x * 6 x ( ) *Y. Ding, HBEB, /9 Slide 6

7 Advanced Design Concepts 5 pc, Based on New Ideas Using eigen-emittances to lower transverse emittances Pre-bunching beam at 4Å and energy-staged HGHG sections 5 pc, 5 fsec, 3.4 ka,.% energy spread.5 µm emittance 4 GW, 9 X-rays ~ -5 spectral bandwidth Slide 7

8 MaRIE Advanced XFEL Block Diagram Components.7/.7/.4 µm 3.3/.5/.4 µm.5/.5/ µm Beam manipulation section Injector Acceleration to MeV Foil /other eigen-optics chicanes to compress bunch Acceleration to GeV Optics for prebunching 3 Accel to 5 GeV st HGHG section Modulation chicane Accel to GeV nd HGHG section Modulation chicane Accel to GeV XFEL radiator 4 FEL section.5/.5/ µm. Can we keep the longitudinal emittance low?. Will this work? Foil? Transversely tapered undulator? 3. Can we make optics linear enough to pre-bunch? Should use optically self-seed? 4. Can we design this section so the harmonic current is preserved? Slide 8

9 We Have Thought About Four Ways to Get Low Emittances. Thin pancake with axial field. Asymmetric beam with laser tilt 3. Magnetized photoinjector and nonsymplectic foil/undulator (using ISR) 4. General three-dimensional couplings We are currently evaluating these options We typically consider an ideal photoinjector with nominal emittances (x,y,z) of.7/.7/.4 µm, with target eigen-emittances of.5/.5/3 µm, but 4: ratio in final transverse emittances almost as good (z-emittance can actually be as high as µm) The problem comes down to how low the energy spread (and longitudinal emittance) can be maintained Slide 9

10 Foil Idea May Work, Stimulating Other Concepts We nominally start with a magnetized photoinjector to get ε x, n / ε y, n / ε z, n = 3.3/.5/.4 µm Non-symplectic element separates issues and simplifies design. Induced angular scattering and increased energy spread limit effectiveness, still might get factors of ten improvement slew / Intrinsic energy spread and emittance γ γ + γ ind γ int ε ( ) / γ x, final = εind + ε x, int ε z, final = γ σ z γ γ slew γ You can do an exact eigen-emittance recovery, if you wish, but it s hard, prone to second-order effects, and you don t need to simple asymmetric chicane works fine M s-chicane = L η η ε L η η = ε L t η η ε t L t = L + L η = η η ε = ε + ε t η =.49 m ε ( ε + ε ) 4 x ε z = ε x ε z + η x z x z + η x z The growth in the product of the emittances of only about %. Slide

11 Spectral Bandwidth Decreases from -3 to 5x -5 with Cascaded HGHG (here all at GeV, unoptimized) EEX Pre-buncher Harmonic current at 4 Å (%) RMS energy spread (%).5 Can optically seed also First HGHG (4 Å) Peak energy modulation (MeV).57 RMS energy spread (%). First Chicane R56 (Å/( γ/γ)) 4. Harmonic current at 4 Å (%) 67.6 Harmonic current at Å (%) 6. Second HGHG ( Å) Peak energy modulation (MeV) 3.35 RMS energy spread (%).5 Second Chicane R56 (Å/( γ/γ)) 55. Harmonic current at Å (%) 5.5 Harmonic current at ¼ Å (%).9 Slide

12 More Technical Details: Eigen-emittance oral talk (Duffy) 4:3 today (Beam Dynamics IV) WEP33 Using an Emittance Exchanger as a Bunch Compressor WEP34 Beam Masking and Its Smearing due to ISR-Induced Energy Diffusion (Yampolsky) THP6 Simulations of XFEL Output from Beams Conditioned with Emittance Partitioning and Electron Pre-Bunching (Marksteiner) MaRIE Overview Posters: THP45 Proposed Facility Layout for MaRIE (O Toole) THP63 Pre-Conceptual Design Requirements for an X-Ray Free- Electron Laser for the MaRIE Experimental Facility at LANL (Sheffield) Slide