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SSSEPB Discussion T opics

SSSEPB Discussion T opics. Dao Xiang, On behalf of the organizing committee July-22-2013. 10 groups. List of topics. Electron sources Thermal emittance of conventional cathodes; Novel electron sources ( nanotip , ultracold beam source);. Beam dynamics

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SSSEPB Discussion T opics

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  1. SSSEPB Discussion Topics Dao Xiang, On behalf of the organizing committee July-22-2013

  2. 10 groups

  3. List of topics • Electron sources • Thermal emittance of conventional cathodes; • Novel electron sources (nanotip, ultracold beam source); • Beam dynamics • Blowout regime for generation of ellipsoidal beam. • Emittanceexchange; • Slice energy spread growth in photoinjectors; • Coherent synchrotron radiation in magnetic bunch compressors. • Application of FELs • Coherent diffraction imaging. • Measuring e-beam and photon beam • Transverse coherence; • Laser based methods to measure ultrashort electron beam temporal profile; • Measure ultrashort x-ray profile in FELs; • Measure micron size electron beam with synchrotron radiation interferometer • Enhancing FEL capabilities • Laser heater; • Temporal coherence; • Self-seeding; • Generation of attosecond x-ray pulse. • Plasma accelerator • External injection; • Plasma accelerator based light source. • Other novel concepts • Inverse Compton scattering based x-ray light source; • Inverse free-electron laser accelerator; SSSEPB Discussion Topics

  4. 1. Thermal emittance of conventional cathodes Thermal emittance sets the lower limit • References • D. Dowell and J. Schmerge, Phys. Rev. ST Accel. Beams 12, 074201 (2009). • J. E. Clendenin et al., SLAC-PUB-8284, 1999. • C. P. Hauri et al., Phys. Rev. Lett. 104, 234802 (2010). • H. Qian et al., Phys. Rev. ST Accel. Beams 15, 040102 (2012). • Understand the emission process • What determines thermal emittance? • How to reduce thermal emittance? Gun Linac Linac Bunch compressor Undulator x-ray thermal emittance emittance coherent synchrotron radiation space charge z photoelectrons laser cathode SSSEPB Discussion Topics

  5. 2. Novel electron sources • References • P. Hommelhoff et al., Phys. Rev. Lett. 96, 077401 (2006) • B. J. Claessens et al., Phys. Rev. Lett. 95, 164801 (2005) • A. J. McCulloch et al., Nature Physics 7, 785 (2011) • R.K. Li et al., Phys. Rev. Lett. 110, 074801 (2013) • A.Polyakov et al., Phys. Rev. Lett. 110, 076802 (2013) • Understand the physics • Advantages and disadvantages • Challenges Nanotip cathode (field emission array) Nanostructured cathode Ultracold electron source SSSEPB Discussion Topics

  6. 3. Blowout regime for generation of ellipsoidal beam • References • O.J. Luiten et al., Phys. Rev. Lett. 93, 094802 (2004) • P. Musumeci et al., Phys. Rev. Lett. 100, 244801 (2008) • B. O’Shea et al., Phys. Rev. ST Accel. Beams 14, 012801 (2011) • P. Piot et al., Phys. Rev. ST Accel. Beams 16, 010102 (2013) • Y. Li and J. Lewellen, Phys. Rev. Lett. 100, 074801 (2008) • Understand the physics • Advantages and disadvantages • Sensitivity to laser parameters and charge Space charge induced emittance growth Experimental realization • Recipes to ellipsoidal beam • 3-D laser pulse shaping • Blowout regime: an ultrashort laser with an appropriate transverse profile is used to generate a short beam that automatically evolves to an ellipsoidal beam through longitudinal expansion SSSEPB Discussion Topics

  7. 4. Emittance exchange 0 0 • Understand the physics • Advantages and disadvantages • Applications The ability to tailor a beam’s 6D distribution is one of the ultimate goals in accelerator physics. • References • M. Cornacchia and P. Emma, Phys. Rev. ST Accel. Beams 5, 084001 (2002). • P. Emma, Z. Huang, K.-J. Kim, and P. Piot, Phys. Rev. ST Accel. Beams 9, 100702 (2006). • Y.-E Sun et al., Phys. Rev. Lett. 105, 234801 (2010). • D. Xiang and A. Chao, Phys. Rev. ST Accel. Beams 14, 114001 (2011). • D. Xiang, SLAC-PUB-15196, (2012). Applications in shaping e-beam Use masks to shape beam x-distribution, and then use EEX to shape z-distribution. ‘Beam by design’ 0 Beam line 0 0 0 0 0 Varian's collimator SSSEPB Discussion Topics

  8. 5. Slice energy spread growth in a photoinjector • References • J. T. Moody et al., Phys. Rev. ST Accel. Beams 12, 070704 (2009) • Z. Huang et al., Proceedings of PAC2005, p3570, 2005. • M. Huning and H. Schlarb, Proceedings of PAC03, p2074, 2003. • Z. Huang, SLAC-TN-05-026, 2005. • G. Stupakov and Z. Huang, Phys. Rev. ST Accel. Beams 11, 014401 (2008). • Understand the cause of slice energy spread growth • How to reduce slice energy spread Beam slice energy spread quickly grows from ~eV to ~keV in a photoinjector • Possible causes • RF field (Ez depends on x and y) • Longitudinal space charge field • Intrabeam scattering SSSEPB Discussion Topics

  9. 6. Coherent synchrotron radiation in magnetic bunch compressors • References • E. Saldin et al., Nuclear Instruments and Methods in Physics Research Section A, 398, 373 (1997). • H. Braun et al., Phys. Rev. ST Accel. Beams 3, 124402 (2000). • M. Borland, Phys. Rev. ST Accel. Beams 4, 070701 (2001). • K. Bane et al., Phys. Rev. ST Accel. Beams 12, 030704 (2009). • LCLS Conceptual Design Report, Chapter 7, 2002. • Understand the scaling of CSR effects • Understand how CSR increases bend plane projected emittance • Understand how to properly design a bunch compressor to mitigate CSR induced emittance growth CSR increases beam emittance and energy spread, and reduces peak current SSSEPB Discussion Topics

  10. 7. Laser heater • References • Z. Huang et al., Phys. Rev. ST Accel. Beams 7, 074401 (2004). • J. Wu et al., SLAC-PUB-10430, 2004. • Z. Huang et al., Phys. Rev. ST Accel. Beams 13, 020703 (2010). • C. Behrens, Z. Huang and D. Xiang, Phys. Rev. ST Accel. Beams 15, 022802 (2012). • Understand microbunching instability • How laser heater works • Reversible heater Microbunching instability (uBI) • SMALL initial modulation gets amplified and leads to SERIOUS degradations to beam quality • A laser heater increases beam slice energy spread to suppress uBI undulator injector injector undulator With laser heater Without laser heater laser undulator beam SSSEPB Discussion Topics

  11. 8. Temporal coherence of SASE FELs • References • R. Bonifacio, L. De Salvo, P. Pierini, N. Piovella, and C. Pellegrini, Phys. Rev. Lett. 73, 70 (1994). • E. Saldin, E. Schneidmiller, and M. Yurkov, Optics Communications 148, 383 (1998). • J. Wu, C. Pellegrini, and A. Marinelli, Proceedings of FEL12, 2012. • D. Xiang, Y. Ding, Z. Huang and H. Deng, Phys. Rev. ST Accel. Beams 16, 010703 (2013). • B. W. J. McNeil,, N. R. Thompson, and D. J. Dunning, Phys. Rev. Lett. 110, 134802 (2013). • Understand statistic properties of radiation produced in a SASE FEL • Various ways to improve temporal coherence and their pros and cons Self-amplified spontaneous emission (SASE) FELs start from shot noise • In SASE FELs, radiation overtakes e-beam by one radiation wavelength λ per undulatorperiod • Radiation fields with distance larger than Nλ evolve independently and therefore are uncorrelated in phase • iSASE, pSASE, HB-SASE to improve temporal coherence e-beam N N N SASE FEL power profile SSSEPB Discussion Topics

  12. 9. Self-seeding in SASE FELs • References • J. Feldhaus et al., Opt. Communications, 140, 341 (1997). • G. Geloni, V. Kocharyan, and E. Saldin, Journal of Modern Optics, 58, 1391 (2011). • Y. Ding, Z. Huang and R. Ruth, Phys. Rev. ST Accel. Beams 13, 060703 (2010). • J. Amann et al., Nature Photonics 6, 693 (2012). • Understand the physics of various self-seeding configurations • Advantages and disadvantages • How to improve the power stability of a self-seeded SASE FEL Introducing a seed with excellent temporal coherence to dominate over shot noise allows generation of fully coherent x-rays in a SASE FEL SASE monochromator amplify to GW SSSEPB Discussion Topics

  13. 10. Generation of attosecond x-ray pulses in FELs • References • Y. Ding et al., Phys. Rev. Lett. 102, 254801 (2009). • J. Rosenzweig et al., Nucl. Instrum. Methods Phys. Res., Sect. A 593, 39 (2008). • P. Emma et al., Phys. Rev. Lett. 92, 074801 (2004). • I. P. S. Martin and R. Bartolini, Phys. Rev. ST Accel. Beams 14, 030702 (2011). • Understand the physics • Advantages and disadvantages Faster pulses are needed to explore the dynamics of fast events Compress a low charge beam Using a few-cycle laser Slotted foil in a chicane SSSEPB Discussion Topics

  14. 11. Transverse coherence • References • Vartanyants et al., Phys. Rev. Lett. 107, 144801 (2011) • Z. Huang and K.-J. Kim, Phys. Rev. ST Accel. Beams 10, 034801 (2007) • A. Singer et al., Optics Express 20, 17480 (2012) • M.D. Alaimo et al., Phys. Rev. Lett. 103, 194805 (2009) • Why FEL has good transverse coherence • How to measure transverse coherence Coherence is a degree of predictability What do they need? -Coherence! FEL has good transverse coherence Young’s double slit z pinhole for synchrotron radiation Gain guiding in FEL SSSEPB Discussion Topics

  15. 12. Laser based methods to measure ultrashort e-beam • References • E. Saldin et al., Nuclear Instruments and Methods in Physics Research Section A, 539, 499 (2005). • G. Andonian et al., Phys. Rev. ST Accel. Beams 14, 072802 (2011). • Y. Ding et al., Proceedings of FEL2011, p431, Shanghai, 2011. The wavelength of optical laser may be a perfect ruler to measure e-beam Optical replica synthesizer Optical oscilloscope Optical streaking • Understand the physics • Advantages and disadvantages x e- TCAV undulator SSSEPB Discussion Topics

  16. 13. Measure ultrashort x-ray pulses in FELs • References • U. Frühling, Nature photonics, 3, 523 - 528 (2009). • Y. Ding et al., Phys. Rev. ST Accel. Beams 14, 120701 (2011). • Y. Inubushi et al., Phys. Rev. Lett. 109, 144801 (2012). • Y. Ding et al., Phys. Rev. Lett. 109, 254802 (2012). • Understand the physics • Advantages and disadvantages • Challenges THz streaking Correlation functions Measure what x-ray does to e-beam correlation in time correlation in frequency SSSEPB Discussion Topics

  17. 14. Synchrotronradiation interferometer • References • T. Mitsuhashi and T. Naito, Proceedings of EPAC98, p1565, 1998. • T. Naito and T. Mitsuhashi, Phys. Rev. ST Accel. Beams 9, 122802 (2006). Determine beam size from visibility of interference pattern Speckles from an incoherent source Synchrotron radiation interferometer Michelson stellar interferometer • Understand the physics • Applications and limitations SSSEPB Discussion Topics

  18. 15. External injection in plasma accelerator • References • E. Esarey, C. P. Schroeder, and W. P. Leemans, Review of Modern Physics, 81, 1229 (2009) • H. Suk, N. Barov, J. B. Rosenzweig, and E. Esarey, Phys. Rev. Lett. 86, 1011 (2001) • J. Faure et al., Nature 444, 737, 2006 • A. Pak et al., Phys. Rev. Lett. 104, 025003 (2010). • B. Hidding et al., Phys. Rev. Lett. 108, 035001 (2012). Ultrashort laser pulse used to optically trigger the injection of electrons Self injection Plasma photocathode Colliding pulse injection • Understand the physics • Advantages and disadvantages SSSEPB Discussion Topics

  19. 16. Plasma accelerator based light source • References • M. Fuchs et al., Nat. Phys. 5, 826 (2009). • A. R. Maier et al., Phys. Rev. X.2, 031019 (2012). • Z. Huang, Y. Ding, C. Schroeder, Phys. Rev. Lett. 109, 204801 (2012). • L. Chen et al., Nature Scientific Reports 3, 1912 (2013). • S. Corde et al., Rev. Mod. Phys. 85, 1 (2013). Cheaper and more compact Undulator radiation Realizing FEL gain Betatron radiation • Understand the physics • Understand the challenges SSSEPB Discussion Topics

  20. 17. Coherent diffraction imaging • References • J. Zuo et al., Science 300, 1419 (2003). • H. Chapman et al., Nature physics, 2, 839 (2006). • H. Chapman and K. Nugent, Nature Photonics 4,833 (2010). • H. Chapman et al., Nature, 470, 73 (2011). • M. Seibert et al., Nature, 470, 78 (2011). ‘lensless’ technique for 3D structure determination How to form an image? Diffraction before destruction Replace the lens with software • Understand the physics • Understand source requirements • Applications and challenges SSSEPB Discussion Topics

  21. 18. Inverse Compton scattering (ICS) based x-ray source • References • I.V. Pogorelsky et al., Phys. Rev. ST Accel. Beams 3, 090702 (2000). • F. V. Hartemann et al., Phys. Rev. ST Accel. Beams 8, 100702 (2005). • A. Bacci et al., Phys. Rev. ST Accel. Beams 9, 060704 (2006). • Z. Huang and R. Ruth, Phys. Rev. Lett. 80, 976 (1998). Using lasers as undulators for generation of short-wavelength radiation Why and how Gain in ICS Increase number of photons / second • Understand the physics • How to increase photons per second? • How to get gain? laser e-beam SSSEPB Discussion Topics

  22. 19. Inverse free-electron laser accelerator • References • E. Courant, C. Pellegrini and W. Zakowicz, Phys. Rev. A 32, 2813 (1985). • W. D. Kimura et al., Phys. Rev. Lett. 86, 4041 (2001). • J. P. Duris, P. Musumeci, and R. K. Li, Phys. Rev. ST Accel. Beams 15, 061301 (2012). • M. Dunning et al., Phys. Rev. Lett. 110, 244801 (2013). Using lasers to boost electron beam energy in an undulator FEL and inverse FEL Cascading in inverse FELs ~GV/m gradient with optimizations • Understand the physics • How to improve beam quality • Applications and limitations In an FEL, the energy of electron beam is transferred to the radiation field; in an inverse FEL, the energy of radiation (typically a high power laser) is transferred to electron beam Laser waist size, undulator tapering SSSEPB Discussion Topics

  23. SSSEPB discussion sessions • To-do-list: • Each group choose one topic from the list (Monday) • Read papers and have discussions with group members in the afternoon sessions (Tuesday, Wednesday, Thursday) • Each group have one representative give a 10-minute talk (~10 slides) (Friday morning) • Get references here ‘ http://www.slac.stanford.edu/~dxiang/ ’ Wish you a fun and productive week @ SLAC SSSEPB Discussion Topics

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