Post on 12-Jan-2016
SSSEPB working group discussion topics
Gabriel Marcus, on behalf of the organizing committee
August 3-7, 2015
2
Working groups
• 1.5 hours at the end of each day will be dedicated to
working groups
• ~ 4 students per group
• Choose a topic relevant to the SSSEPB material
• A list of suggested references will be provided
• Prepare a short (15 – 20 minute) presentation on the
chosen topic to be given by one group member on Friday
3
10 groups
number name
1 A AbuAli D Khan G WangZ Wang
L Gupta 7
2 M Hamamou S Li
3 E Curry J MacArthur Y Xu K LarsenA Hanuka
13
4 D Cesar A Hanna M Croia O Mohsen 14
5 C Emma J Franssen MK Weikum X Nie 3
6 C-K Huang D Yang A Halavanau P Niknejadi 12
7 N Sudar Q Gao A Vrielink ZH Guo 6
8 E Welch S Mohamed L Zeng W Qin 16
9 X Xu T Rui G Campogiani M Sangroula 9
10 I Ali L Zheng J Scifo M Marongiu 4
4
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.
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;
Enhancing FEL capabilities
Laser heater;
Temporal coherence;
Self-seeding;
Generation of attosecond x-ray pulse.
Plasma accelerator
External injection;
Plasma accelerator based light source.
SSSEPB Discussion Topics
Other novel concepts
Inverse Compton scattering based x-ray light
source;
Inverse free-electron laser accelerator;
5
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).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
6
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)
SSSEPB Discussion Topics
Understand the physics Advantages and disadvantages Challenges
Nanotip cathode (field emission array)
Nanostructured cathode
Ultracold electron source
7
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)
SSSEPB Discussion Topics
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
8
4. Emittance exchange
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).SSSEPB Discussion Topics
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 xx
R R R R xx
R R R R zz
R R R R
0 0
0 00 0
0 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’
9
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).
SSSEPB Discussion Topics
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
10
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.
SSSEPB Discussion Topics
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
11
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).
SSSEPB Discussion Topics
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
12
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).
SSSEPB Discussion Topics
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 period
Radiation 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
13
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).
SSSEPB Discussion Topics
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
monochromator
SASE
amplify to GW
14
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).
SSSEPB Discussion Topics
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
15
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)
SSSEPB Discussion Topics
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
zGain guiding in FEL
pinhole for synchrotron radiation
16
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.
SSSEPB Discussion Topics
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
undulator
x
TCAVe-
17
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).
SSSEPB Discussion Topics
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
18
14. 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).
SSSEPB Discussion Topics
Ultrashort laser pulse used to optically trigger the injection of electrons
Self injection
Plasma photocathode
Colliding pulse injection
Understand the physics Advantages and disadvantages
19
15. 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).
SSSEPB Discussion Topics
Cheaper and more compact
Undulator radiation
Realizing FEL gain
Betatron radiation
Understand the physics Understand the challenges
20
16. 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).
SSSEPB Discussion Topics
‘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
21
17. 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).
SSSEPB Discussion Topics
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?
e-beam
laser
22
18. 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).
SSSEPB Discussion Topics
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
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SSSEPB discussion sessions
SSSEPB Discussion Topics
To-do-list:
- Each group will choose one topic from the list (Monday)- Read papers and have discussions with group members in the
afternoon sessions (Monday – Thursday)- Each group have one representative give a 15 – 20 minute talk
(~15 slides) (Friday morning)- Get references from me or from other tutors
Have a fun and productive
week at SLAC!