sssepb discussion t opics

SSSEPB Discussion Topics

Dao Xiang, On behalf of the organizing committeeJuly-22-2013

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10 groups

number name1 Cesar, D Deng, L Giorgianni, F Wacker, V

2 Huang, R Jhalani, V Shaw, J Vafaei-Najafabadi, N

3 Roberts, K Vrielink, A Wein, J Zeng, H

4 Chaikovska, I Fu, F Grandsaert, T

Lueangaramwong, A

Poor Rezaei, K

5 Chen, Q Curry, E Fuhs, G Vodnala, P Wen, X

6 Derksen, J Fang, Y Howe, I Hu, T Karger, O

7 Emma, C Ferrari, E Heinemann, T

Wang, Zhiwen Wang, D

8 Hanuka, A Pirez, E Turgut, O Xia, Y Zhang, Zhe

9 Li, S Massimo, F Pompili, R Volta, L Yang, J

10 Nause, A Pfeiffer, S Vella, A Villa, F Zhang, Zhen

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List of topics

Electron sourcesThermal emittance of conventional cathodes; Novel electron sources (nanotip, ultracold beam source);

Beam dynamicsBlowout regime for generation of ellipsoidal beam.Emittance exchange;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 capabilitiesLaser heater; Temporal coherence;Self-seeding;Generation of attosecond x-ray pulse.

Plasma acceleratorExternal injection; Plasma accelerator based light source.


Other novel conceptsInverse Compton scattering based x-ray light source; Inverse free-electron laser accelerator;

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1. Thermal emittance of conventional cathodes

Thermal emittance sets the lower limit

ReferencesD. 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).SSSEPB Discussion Topics

Gun Linac Bunch compressor Linac Undulator

emittance

Understand the emission process What determines thermal emittance? How to reduce thermal emittance?

cathode

laser

photoelectrons

space charge

coherent synchrotron radiation

z

x-ray

thermal emittance

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2. Novel electron sources

ReferencesP. 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

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3. Blowout regime for generation of ellipsoidal beam

ReferencesO.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 beam3-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

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4. Emittance exchange

ReferencesM. 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).


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. Beam line

11 12 13 14 0

21 22 23 24 0

31 32 33 34 0

41 42 43 44 0

''R R R R xxR R R R xxR R R R zzR R R R

0 00 0

0 00 0

Applications in shaping e-beamUse masks to shape beam x-distribution, and then use EEX to shape z-distribution.

Varian's collimator

‘Beam by design’

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5. Slice energy spread growth in a photoinjector

ReferencesJ. 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 causesRF field (Ez depends on x and y)Longitudinal space charge fieldIntrabeam scattering

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6. Coherent synchrotron radiation in magnetic bunch compressors

ReferencesE. 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

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7. Laser heater

ReferencesZ. 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

Without laser heater

injector undulator

With laser heater

injector undulator

undulator

laser

beam

A laser heater increases beam slice energy spread to suppress uBI

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8. Temporal coherence of SASE FELs

ReferencesR. 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 noiseIn SASE FELs, radiation overtakes e-beam by one radiation wavelength λ per undulator periodRadiation fields with distance larger than Nλ evolve independently and therefore are uncorrelated in phase

N N N

SASE FEL power profile

iSASE, pSASE, HB-SASE to improve temporal coherence

e-beam

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9. Self-seeding in SASE FELs

ReferencesJ. 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

monochromatorSASE

amplify to GW

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10. Generation of attosecond x-ray pulses in FELs

ReferencesY. 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 eventsCompress a low charge beam

Using a few-cycle laser

Slotted foil in a chicane

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11. Transverse coherence

ReferencesVartanyants 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 predictabilityWhat do they need? -Coherence!

FEL has good transverse coherence

Young’s double slit

zGain guiding in FEL

pinhole for synchrotron radiation

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12. Laser based methods to measure ultrashort e-beam

ReferencesE. 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


undulator

x

TCAVe-

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13. Measure ultrashort x-ray pulses in FELs

ReferencesU. 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

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14. Synchrotron radiation interferometer

ReferencesT. 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 patternSpeckles from an incoherent source

Synchrotron radiation interferometer

Michelson stellar interferometer

Understand the physics Applications and limitations

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15. External injection in plasma accelerator

ReferencesE. 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, 2006A. 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


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16. Plasma accelerator based light source

ReferencesM. 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 compactUndulator radiation

Realizing FEL gain

Betatron radiation

Understand the physics Understand the challenges

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17. Coherent diffraction imaging

ReferencesJ. 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

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18. Inverse Compton scattering (ICS) based x-ray source

ReferencesI.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 radiationWhy and how

Gain in ICS

Increase number of photons / second

Understand the physics How to increase photons per second? How to get gain?

e-beam

laser

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19. Inverse free-electron laser accelerator

ReferencesE. 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 undulatorFEL 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

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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

http://www.slac.stanford.edu/~dxiang/



sssepb discussion t opics

Documents

ultrashort electron

ultrashort laser

st accel

laser parameters

transverse coherence

measuring ebeam

attosecond xray pulse

appropriate transverse