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Low-Energy Undulator Test Line Project Overview

Explore the LEUTL project, FEL/Particle Beam Science, user science & future goals of ALFF. Includes undulator systems, APS SASE FEL goals, measurements, ionization potentials, and enhancements for ALFF success.

haroldjwilliams
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Low-Energy Undulator Test Line Project Overview

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  1. THE LEUTL* -> ALFF# Project ] [ * Low-Energy Undulator Test Line # Argonne Linear FEL Facility Stephen Milton 9/03

  2. This Talk is About • LEUTL • What it is • What it has done • Some FEL/Particle Beam Science • Some FEL User Science • What we want it to become ALFF A user facility for both traditional users and for beam physicists

  3. An Overview

  4. Undulator Systems WBS 1.2.3 Undulator Systems WBS 1.4 Office of Science U.S. Department of Energy Pioneering Science andTechnology

  5. The APS SASE FEL Schematic The Low-Energy Undulator Test Line System Present Configuration APS SASE Project Goals • Characterize the SASE FEL output and perform experiments with it. • Assess the challenges associated with producing a SASE FEL in preparation for an x-ray regime machine.

  6. Basic Parameters for the APS FEL

  7. Some Measurements

  8. CCD Camera Filter Wheels YAG/OTR screen Mirror, mirror w/hole Quadrupole & Corrector Button BPM Undulator Line Diagnostics

  9. 7 . 1 10 6 . 1 10 5 . 1 10 4 . 1 10 3 . Ipeak 266 A 1 10 Intensity [arb. units] bunch length 0.3 ps 100 charge 200 pC 10 emittance 8.5 mm energy spread  0.1% 1 Lg, theor. 0.59 m 0.1 Lg, meas. 0.57 m 0.01 0 5 10 15 20 25 Distance [m] Optical Intensity vs. Distance: Gain

  10. 7 . 1 10 6 . 1 10 5 . 1 10 4 . 1 10 3 . 1 10 Optical Intensity Statistics 0.75 Unsaturated Intensity [arb. units] Norm. Std. Dev. Intensity 100 Saturated 10 1 0.1 0.25 0.01 0 5 10 15 20 25 Distance [m]

  11. Ipeak 266 A bunch length 0.3 ps Ipeak 256 A charge 200 pC bunch length 0.25 ps emittance 8.5 mm charge 160 pC energy spread  0.1% emittance 6.7 mm Lg, theor. 0.59 m energy spread  0.1% Lg, meas. 0.57 m Lg, theor. 0.54 m Lg, meas. 0.7 m Trajectory & Matching Effects 6 10 5 10 4 10 3 10 Intensity [arb. units] 100 10 1 0.1 0 5 10 15 20 25 Distance [m]

  12. 6 10 5 10 4 10 3 10 Microbunching Measurement SASE light Intensity [arb. units] CTR light 100 10 1 0.1 0 5 10 15 20 25 Distance [m]

  13. ALFF

  14. Ionization Potentials Just about everything loses electrons somewhere from a few eV (400 nm) to near 20 eV (50 nm) and molecules are no exception. Note: Isomers always have ionization potentials higher than the “ground state”

  15. Improvements

  16. Enhancements • New Photocathode RF Gun System • Laser System • High-Performance RF Gun • Linac Improvements • New 1st accelerating structure • Improved and additional diagnositcs • Transport Line Improvements • Undulator VUV Diagnostics Improvements • VUV Optical Transport Improvements • Interleaving Capabilities

  17. Interleaving Our ability to make ALFF a success will be very dependent upon our ability to make interleaving a reality.

  18. ALFF Scientific “Grand Challenges”

  19. The chemical structure of a possible alteration of guanosine by reaction with an aryl amine. How Does Cancer Begin? Molecular trace analysis suitable for cancer research has not been possible on samples from individuals. The new end station at ANL promises to be the most sensitive and discriminative instrument in the world and will enable these analyses.

  20. Schematic drawing of X-wind emanating from a young Stellar Object. This model for the evolution of our solar system explains many recent meteoritical discoveries and can now be tested using solar wind samples from the Genesis spacecraft and the SPIRIT end station on the ALFF. How Did Our Sun Evolve? Determination of how our sun evolved by performing isotopic analysis on extraterrestrial material is now possible using resonant ionization mass spectroscopy; however, accurate measurement of light elements such as oxygen and nitrogen is only possible with a tunable laser capable of reaching VUV wavelengths and with sufficient energy per pulse. The ALFF, together with the SPIRIT apparatus, will be the most sensitive system in the world for this important measurement.

  21. Selective Chemical Bond Breaking Chemical bonds in molecules can be selectively broken with intense, carefully modulated short pulses of light. Extending this practice to the VUV broadens the applicability of this technique to a large number of species and enables one to precisely study their excited states.

  22. The First Experiment

  23. The First APS FEL Experiment M. Pellin MSD/ANL LEUTL

  24. The First APS FEL Experiment Single Photon Ionization / Resonant Ionization to Threshold (SPIRIT)M. Pellin, Jerry Moore, Wally Callaway, and Others, ANL+ SPIRIT will use the high VUV pulse energy from LEUTL to uniquely study – • Trace quantities of light elements: H, C, N, O in semiconductors with 100 times lower detection limit • Organic molecules with minimalfragmentation cell mapping by mass becomes feasible polymer surfaces modified (carcinogenic) DNA photoionization thresholds • Excited states of molecules cold wall desorption in accelerators sputtering of clusters Operating Since 2002

  25. First Measurements Photoionization of Gold and Gold clusters • Only secondary ions below the ionization potential (IP) of Au • FEL wavelength 127 nm (9.8 eV) • IP of Au equals 9.2 eV • Light atoms and molecules are also observed • H peak may be due to fragmentation of molecules.

  26. Challenges to Accelerator and FEL Development

  27. Incomplete List • Electron Beam Brighness Enhancement and Preservation • “Bread and Butter” • Wavelength Extension • Exploitation of Harmonics • Femtosecond/Attosecond Pulses • Capitalize on the tremendous bandwidth • Other

  28. A possible scheme to synchronize the SASE FEL pulse to an external laser operating at an independent wavelength. Multiple Arbitrary Wavelengths in a Single Pulse Many experiments need precisely timed, multiple wavelengths to excite and then probe the sample under study. Although the SASE-FEL system will generate multiple wavelengths via nonlinear harmonics, completely arbitrary wavelength generation within a single bunch has yet to be accomplished.

  29. The concept of wavelength shifting. Advanced Seeding There is tremendous interest in seeding the FEL process in order to stabilize the shot-to-shot fluctuations in optical power output and to narrow the bandwidth. With the exception of self-seeding techniques, however, there are no existing arbitrarily tunable wavelength sources suitable for generating seed pulses. If one could seed with a fixed wavelength and later shift that wavelength arbitrarily, this problem could be overcome.

  30. Summarizing • LEUTL to be Converted to a user facility: ALFF • Need DOE support • Workshop to be held over October 30 and 31st in support of the scientific case • ALFF Designed to • Support the traditional VUV scientist’s needs • Also be available to beam physicists for exploration of FEL and beam brightness science

  31. And before ending OK, I’m Done.Thank you! We have submitted a proposal to DOE last June and they requested that we gauge the scientific interest with a workshop (Oct. 30 and 31st.) Don’t worry. This is the last Slide. We are hoping for real funding in FY05.

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