A bunch compressor design and several X-band FELs Yipeng Sun, ARD/SLAC 2011-04-13, LCLS-II meeting.
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Transcript of A bunch compressor design and several X-band FELs Yipeng Sun, ARD/SLAC 2011-04-13, LCLS-II meeting.
![Page 1: A bunch compressor design and several X-band FELs Yipeng Sun, ARD/SLAC 2011-04-13, LCLS-II meeting.](https://reader035.fdocuments.in/reader035/viewer/2022062315/5697bf8b1a28abf838c8b188/html5/thumbnails/1.jpg)
A bunch compressor designand several X-band FELs
Yipeng Sun, ARD/SLAC
2011-04-13, LCLS-II meeting
![Page 2: A bunch compressor design and several X-band FELs Yipeng Sun, ARD/SLAC 2011-04-13, LCLS-II meeting.](https://reader035.fdocuments.in/reader035/viewer/2022062315/5697bf8b1a28abf838c8b188/html5/thumbnails/2.jpg)
Presentation TitlePage 2
Design of two bunch compressors
![Page 3: A bunch compressor design and several X-band FELs Yipeng Sun, ARD/SLAC 2011-04-13, LCLS-II meeting.](https://reader035.fdocuments.in/reader035/viewer/2022062315/5697bf8b1a28abf838c8b188/html5/thumbnails/3.jpg)
Bunch compressionPage 3
Magnetic bunch compression
e- source
Energy modulation (correlation):RF structure, laser, wake field etc.
RF3-Dip. Chicane
Dispersive region:chicane, wigglerarc, dogleg etc.
Bunch L phase space
![Page 4: A bunch compressor design and several X-band FELs Yipeng Sun, ARD/SLAC 2011-04-13, LCLS-II meeting.](https://reader035.fdocuments.in/reader035/viewer/2022062315/5697bf8b1a28abf838c8b188/html5/thumbnails/4.jpg)
Different bunch compressors
3(4) dipole chicane, R56 <0, T566 >0achromatic to any order
Wiggler, R56 <0, T566 >0achromatic to any order?
Arc, R56 >0, T566 >0
2-Dip. Dogleg w/ quad+sextupole, R56 >0, T566 tunable
Chicane w/ quadrupole+sextupole, R56 tunable, T566 tunable
NLCTA chicane shape
![Page 5: A bunch compressor design and several X-band FELs Yipeng Sun, ARD/SLAC 2011-04-13, LCLS-II meeting.](https://reader035.fdocuments.in/reader035/viewer/2022062315/5697bf8b1a28abf838c8b188/html5/thumbnails/5.jpg)
Bunch compressionPage 5
Dispersion relations
![Page 6: A bunch compressor design and several X-band FELs Yipeng Sun, ARD/SLAC 2011-04-13, LCLS-II meeting.](https://reader035.fdocuments.in/reader035/viewer/2022062315/5697bf8b1a28abf838c8b188/html5/thumbnails/6.jpg)
Bunch compressionPage 6
Bunch compressor with dipoles and drifts
![Page 7: A bunch compressor design and several X-band FELs Yipeng Sun, ARD/SLAC 2011-04-13, LCLS-II meeting.](https://reader035.fdocuments.in/reader035/viewer/2022062315/5697bf8b1a28abf838c8b188/html5/thumbnails/7.jpg)
Bunch compressionPage 7
General chicane (1)
![Page 8: A bunch compressor design and several X-band FELs Yipeng Sun, ARD/SLAC 2011-04-13, LCLS-II meeting.](https://reader035.fdocuments.in/reader035/viewer/2022062315/5697bf8b1a28abf838c8b188/html5/thumbnails/8.jpg)
Bunch compressionPage 8
General chicane (1)
![Page 9: A bunch compressor design and several X-band FELs Yipeng Sun, ARD/SLAC 2011-04-13, LCLS-II meeting.](https://reader035.fdocuments.in/reader035/viewer/2022062315/5697bf8b1a28abf838c8b188/html5/thumbnails/9.jpg)
Bunch compressionPage 9
General chicane (2)
![Page 10: A bunch compressor design and several X-band FELs Yipeng Sun, ARD/SLAC 2011-04-13, LCLS-II meeting.](https://reader035.fdocuments.in/reader035/viewer/2022062315/5697bf8b1a28abf838c8b188/html5/thumbnails/10.jpg)
Bunch compressionPage 10
General chicane (2)
![Page 11: A bunch compressor design and several X-band FELs Yipeng Sun, ARD/SLAC 2011-04-13, LCLS-II meeting.](https://reader035.fdocuments.in/reader035/viewer/2022062315/5697bf8b1a28abf838c8b188/html5/thumbnails/11.jpg)
Presentation TitlePage 11
An FEL withLCLS injector (S-band+X-band
harmonic)Plus X-band Linac2 and Linac3
![Page 12: A bunch compressor design and several X-band FELs Yipeng Sun, ARD/SLAC 2011-04-13, LCLS-II meeting.](https://reader035.fdocuments.in/reader035/viewer/2022062315/5697bf8b1a28abf838c8b188/html5/thumbnails/12.jpg)
Presentation TitlePage 12
Scaling
Total length of acceleratorAssume 70% RF in linac
250-10pC
Final bunch length versus bunch charge
![Page 13: A bunch compressor design and several X-band FELs Yipeng Sun, ARD/SLAC 2011-04-13, LCLS-II meeting.](https://reader035.fdocuments.in/reader035/viewer/2022062315/5697bf8b1a28abf838c8b188/html5/thumbnails/13.jpg)
Presentation TitlePage 13
Longitudinal wake potential
'long' range
![Page 14: A bunch compressor design and several X-band FELs Yipeng Sun, ARD/SLAC 2011-04-13, LCLS-II meeting.](https://reader035.fdocuments.in/reader035/viewer/2022062315/5697bf8b1a28abf838c8b188/html5/thumbnails/14.jpg)
Presentation TitlePage 14
Linac3 length needed for de-chirp after BC2
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Presentation TitlePage 15
Accelerator shape (LCLS injector + X-band)
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Presentation TitlePage 16
LiTrack, LCLS, 250pC, 3kA
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Presentation TitlePage 17
LiTrack, LCLS injector+X-band, 250pC, 3kA
![Page 18: A bunch compressor design and several X-band FELs Yipeng Sun, ARD/SLAC 2011-04-13, LCLS-II meeting.](https://reader035.fdocuments.in/reader035/viewer/2022062315/5697bf8b1a28abf838c8b188/html5/thumbnails/18.jpg)
Presentation TitlePage 18
Optics
LCLS
LCLS-Injector + X-band
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Presentation TitlePage 19
Elegant simulation, 250 pC, 3 kA (w/ and w/o CSR)
LCLS
LCLS w/o CSR
![Page 20: A bunch compressor design and several X-band FELs Yipeng Sun, ARD/SLAC 2011-04-13, LCLS-II meeting.](https://reader035.fdocuments.in/reader035/viewer/2022062315/5697bf8b1a28abf838c8b188/html5/thumbnails/20.jpg)
Presentation TitlePage 20
Elegant simulation, 250 pC, 3 kA
LCLS
LCLS-Injector + X-band (½ R56 in BC2, 0.7 bending angle)
![Page 21: A bunch compressor design and several X-band FELs Yipeng Sun, ARD/SLAC 2011-04-13, LCLS-II meeting.](https://reader035.fdocuments.in/reader035/viewer/2022062315/5697bf8b1a28abf838c8b188/html5/thumbnails/21.jpg)
Presentation TitlePage 21
Elegant simulation, 250 pC, 5 kA
LCLS (L3, 30degree)
LCLS-Injector + X-band (½ R56 in BC2, 0.7 bending angle)
![Page 22: A bunch compressor design and several X-band FELs Yipeng Sun, ARD/SLAC 2011-04-13, LCLS-II meeting.](https://reader035.fdocuments.in/reader035/viewer/2022062315/5697bf8b1a28abf838c8b188/html5/thumbnails/22.jpg)
Presentation TitlePage 22
Elegant simulation, 250 pC, 5 kA, Projected emittance
LCLS (L3, 30degree)
LCLS-Injector + X-band (½ R56 in BC2, 0.7 bending angle)
![Page 23: A bunch compressor design and several X-band FELs Yipeng Sun, ARD/SLAC 2011-04-13, LCLS-II meeting.](https://reader035.fdocuments.in/reader035/viewer/2022062315/5697bf8b1a28abf838c8b188/html5/thumbnails/23.jpg)
Presentation TitlePage 23
Elegant simulation, 250 pC, 5 kA, Trajectory
LCLS (L3, 30degree)
LCLS-Injector + X-band (½ R56 in BC2, 0.7 bending angle)
![Page 24: A bunch compressor design and several X-band FELs Yipeng Sun, ARD/SLAC 2011-04-13, LCLS-II meeting.](https://reader035.fdocuments.in/reader035/viewer/2022062315/5697bf8b1a28abf838c8b188/html5/thumbnails/24.jpg)
Presentation TitlePage 24
LCLS-Injector + X-band (0.5 R56 in BC2, 0.7 bending angle), 250 pC, 5 kA
BC1 end BC2 end Linac3 endBC2 entrance
![Page 25: A bunch compressor design and several X-band FELs Yipeng Sun, ARD/SLAC 2011-04-13, LCLS-II meeting.](https://reader035.fdocuments.in/reader035/viewer/2022062315/5697bf8b1a28abf838c8b188/html5/thumbnails/25.jpg)
Presentation TitlePage 25
Potential X-band advantage over S-band
• Maintain a flat energy profile when pushing for shorter bunch length and higher peak current (i.e. 6kA at 250pC), due to stronger X-band longitudinal wake in Linac3, to remove energy correlation (chirp); plus possible cancellation of nonlinear chirp between RF, wake and CSR effects.
• Similar or smaller CSR emittance growth in BC2, benefiting from a weaker dipole and a larger energy correlation generated in Linac2 (previous argument)
• Compact (300m vs 1000m, at 14GeV)
• For LCLS, increasing current from 3kA to 6kA requires a smaller L1 phase to generate a longer bunch in ~400m Linac2, so that the L wake chirp is much smaller, and the bunch is compressed more in BC2 with same L2 phase; if keeping similar L1 phase and increasing L2 phase (i.e. from 36d to 37.5), the final energy profile will be very nonlinear.
![Page 26: A bunch compressor design and several X-band FELs Yipeng Sun, ARD/SLAC 2011-04-13, LCLS-II meeting.](https://reader035.fdocuments.in/reader035/viewer/2022062315/5697bf8b1a28abf838c8b188/html5/thumbnails/26.jpg)
Presentation TitlePage 26
Elegant simulation, 250 pC, 5 kA
LCLS (L1, 19degree; L2, 36degree; L3, 30degree)
LCLS (L1, 22degree; L2, 37.5degree; L3, 0degree)
![Page 27: A bunch compressor design and several X-band FELs Yipeng Sun, ARD/SLAC 2011-04-13, LCLS-II meeting.](https://reader035.fdocuments.in/reader035/viewer/2022062315/5697bf8b1a28abf838c8b188/html5/thumbnails/27.jpg)
Presentation TitlePage 27
An X-band RF based FEL with optics linearization
250 pC
![Page 28: A bunch compressor design and several X-band FELs Yipeng Sun, ARD/SLAC 2011-04-13, LCLS-II meeting.](https://reader035.fdocuments.in/reader035/viewer/2022062315/5697bf8b1a28abf838c8b188/html5/thumbnails/28.jpg)
Bunch compressionPage 28
Bunch length after compression
Final coordinate (square)
Minimum lengthMinimum length
Neglect small initial un-correlated energy spread
1st order optimal compression:
2nd order optimal compression:
3rd order optimal compression:
![Page 29: A bunch compressor design and several X-band FELs Yipeng Sun, ARD/SLAC 2011-04-13, LCLS-II meeting.](https://reader035.fdocuments.in/reader035/viewer/2022062315/5697bf8b1a28abf838c8b188/html5/thumbnails/29.jpg)
Bunch compressionPage 29
Full compression using optics linearization
1st order dispersion
2nd order dispersion
3rd order dispersion
![Page 30: A bunch compressor design and several X-band FELs Yipeng Sun, ARD/SLAC 2011-04-13, LCLS-II meeting.](https://reader035.fdocuments.in/reader035/viewer/2022062315/5697bf8b1a28abf838c8b188/html5/thumbnails/30.jpg)
Bunch compressionPage 30
Minimize CSR (1) short interaction time
![Page 31: A bunch compressor design and several X-band FELs Yipeng Sun, ARD/SLAC 2011-04-13, LCLS-II meeting.](https://reader035.fdocuments.in/reader035/viewer/2022062315/5697bf8b1a28abf838c8b188/html5/thumbnails/31.jpg)
New design BC1 (1) first order
B10.2m7 degree
B20.2m3 degree
B30.2m-3 degree
B40.2m-7 degreeQD
QF
R56 = 17 mm
![Page 32: A bunch compressor design and several X-band FELs Yipeng Sun, ARD/SLAC 2011-04-13, LCLS-II meeting.](https://reader035.fdocuments.in/reader035/viewer/2022062315/5697bf8b1a28abf838c8b188/html5/thumbnails/32.jpg)
New design BC1 (2) second order
SF1&2 SD1&2 symmetricK3(SF1) = -K3(SD2)K3(SF2) = -K3(SD1)
T166 = T266 = 0; T566 = 170 mm
![Page 33: A bunch compressor design and several X-band FELs Yipeng Sun, ARD/SLAC 2011-04-13, LCLS-II meeting.](https://reader035.fdocuments.in/reader035/viewer/2022062315/5697bf8b1a28abf838c8b188/html5/thumbnails/33.jpg)
Bunch compressionPage 33
Minimize CSR (2) phase space matching
general
x
X’
CSR
Large βx
X’
CSR
Small β x
X’
CSR
Optimalβ and α
specific
Optimized to minimize CSR impact on emittance
![Page 34: A bunch compressor design and several X-band FELs Yipeng Sun, ARD/SLAC 2011-04-13, LCLS-II meeting.](https://reader035.fdocuments.in/reader035/viewer/2022062315/5697bf8b1a28abf838c8b188/html5/thumbnails/34.jpg)
Bunch compressionPage 34
X-band based 2 stage FEL (1) 250pc, 300micron
![Page 35: A bunch compressor design and several X-band FELs Yipeng Sun, ARD/SLAC 2011-04-13, LCLS-II meeting.](https://reader035.fdocuments.in/reader035/viewer/2022062315/5697bf8b1a28abf838c8b188/html5/thumbnails/35.jpg)
Presentation TitlePage 35
Final profile at 7GeV (collimation in middle of BC1)
![Page 36: A bunch compressor design and several X-band FELs Yipeng Sun, ARD/SLAC 2011-04-13, LCLS-II meeting.](https://reader035.fdocuments.in/reader035/viewer/2022062315/5697bf8b1a28abf838c8b188/html5/thumbnails/36.jpg)
Presentation TitlePage 36
Slice emittance evolution, 250 pC, 6 kA
BC1 entrance BC2 entrance Linac3 endBC1 end
![Page 37: A bunch compressor design and several X-band FELs Yipeng Sun, ARD/SLAC 2011-04-13, LCLS-II meeting.](https://reader035.fdocuments.in/reader035/viewer/2022062315/5697bf8b1a28abf838c8b188/html5/thumbnails/37.jpg)
Presentation TitlePage 37
An X-band RF based FEL with normal chicane BC
10 pC
![Page 38: A bunch compressor design and several X-band FELs Yipeng Sun, ARD/SLAC 2011-04-13, LCLS-II meeting.](https://reader035.fdocuments.in/reader035/viewer/2022062315/5697bf8b1a28abf838c8b188/html5/thumbnails/38.jpg)
Bunch compressionPage 38
Max bunch length w/o harmonic RF
![Page 39: A bunch compressor design and several X-band FELs Yipeng Sun, ARD/SLAC 2011-04-13, LCLS-II meeting.](https://reader035.fdocuments.in/reader035/viewer/2022062315/5697bf8b1a28abf838c8b188/html5/thumbnails/39.jpg)
Bunch compressionPage 39
Bunch compressor and linac design
BC1 BC2 Linac cell
![Page 40: A bunch compressor design and several X-band FELs Yipeng Sun, ARD/SLAC 2011-04-13, LCLS-II meeting.](https://reader035.fdocuments.in/reader035/viewer/2022062315/5697bf8b1a28abf838c8b188/html5/thumbnails/40.jpg)
X-band based 2 stage FEL (3) 10pc, 40micron
54 MeV (C. Limborg) 6 GeV
![Page 41: A bunch compressor design and several X-band FELs Yipeng Sun, ARD/SLAC 2011-04-13, LCLS-II meeting.](https://reader035.fdocuments.in/reader035/viewer/2022062315/5697bf8b1a28abf838c8b188/html5/thumbnails/41.jpg)
FEL simulation Setup
• FEL at 2 keV , 6 Å (FEL at 8 keV, 1.5 Å)• Electron Charge 10 pC, Centroid Energy 6
GeV, peak current 3 kA with profile as shown in previous slides– S2E file down to undulator entrance
• LCLS Undulator with larger gap lw = 3 cm (1.5 cm); beta-function ~ 15 m
Juhao Wu
![Page 42: A bunch compressor design and several X-band FELs Yipeng Sun, ARD/SLAC 2011-04-13, LCLS-II meeting.](https://reader035.fdocuments.in/reader035/viewer/2022062315/5697bf8b1a28abf838c8b188/html5/thumbnails/42.jpg)
Presentation TitlePage 42
FEL performance
Juhao Wu
1.5 angstrom6 angstrom
![Page 43: A bunch compressor design and several X-band FELs Yipeng Sun, ARD/SLAC 2011-04-13, LCLS-II meeting.](https://reader035.fdocuments.in/reader035/viewer/2022062315/5697bf8b1a28abf838c8b188/html5/thumbnails/43.jpg)
Bunch compressionPage 43
BC parameters summary
![Page 44: A bunch compressor design and several X-band FELs Yipeng Sun, ARD/SLAC 2011-04-13, LCLS-II meeting.](https://reader035.fdocuments.in/reader035/viewer/2022062315/5697bf8b1a28abf838c8b188/html5/thumbnails/44.jpg)
Presentation TitlePage 44
Possible test at NLCTA
![Page 45: A bunch compressor design and several X-band FELs Yipeng Sun, ARD/SLAC 2011-04-13, LCLS-II meeting.](https://reader035.fdocuments.in/reader035/viewer/2022062315/5697bf8b1a28abf838c8b188/html5/thumbnails/45.jpg)
Bunch compressionPage 45
Motivation and simulation condition
Motivationo Demonstrate effective bunch compression (5 to 10 times) with x-band RF
Scheme 1: use normal chicane + positive RF chirp (current NLCTA) Scheme 2: use optics w/ higher order dispersion + positive/negative RF
chirp (need to install 4/6 sextupoles in the big chicane)o Investigate tolerances on timing jitter, misalignment etc.; emittance growth
Simulation condition: In Elegant, including transverse and longitudinal wake, coherent synchrotron
radiation (CSR), longitudinal space charge (LSC) and velocity bunching0.5 million macro-particlesFor scheme 1, current operating opticsFor scheme 2, new optics20 pC beam at 5MeV, 0.5ps RMS bunch length, 5e-3 RMS energy spread, 1
m.mrad transverse emittanceBeam energy: 60 MeV at BC1, 120 MeV at BC2
![Page 46: A bunch compressor design and several X-band FELs Yipeng Sun, ARD/SLAC 2011-04-13, LCLS-II meeting.](https://reader035.fdocuments.in/reader035/viewer/2022062315/5697bf8b1a28abf838c8b188/html5/thumbnails/46.jpg)
Bunch compressionPage 46
NLCTA optics (current operation)
R56 =-73mm T566 = 111mm R56 =-10mm
T566 = 15mm
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Bunch compressionPage 47
Scheme 1 (1) L phase, current and bunch length
Initial
Linac1
BC1
Linac2
BC2
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Bunch compressionPage 48
Scheme 1 (2) no compression, on crest
Initial
Linac1
BC1
Linac2
BC2
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Bunch compressionPage 49
Scheme 1 (3) 2 stage compress 20 times, end
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Bunch compressionPage 50
Scheme 1 (4) effect of timing jitter, near full compression
Timing jitter between laser and RF (assumed same for two RF sections)
On phase + 115 fs (0.5 degree) - 115 fs
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Bunch compressionPage 51
Scheme 1 (5) effect of timing jitter, under compression
Timing jitter between laser and RF (assumed same for two RF sections)
On phase + 115 fs (0.5 degree) - 115 fs
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Bunch compressionPage 52
Scheme 2 (1) optics
Chicane w/ quadrupole+sextupole, R56 tunable, T566 tunable
6 meters long
Install 4/6 sextupoles in the big chicane
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Bunch compressionPage 53
Scheme 2 (2) L phase and current
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Bunch compressionPage 54
Scheme 2 (3) 1 stage compress 10 times, end
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Bunch compressionPage 55
Scheme 2 (4) Sensitivity to timing jitter
Deviation between analytical formulae and simulation due to:Small difference of beam(RF) parameters being employedCollective effects in simulation
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Bunch compressionPage 56
Thank you for your patience!
I would like to thank the following people for their great help and useful discussions:
C. Adolphsen , K. Bane, A. Chao, Y. Cai, Y. Ding, J. England, P. Emma, Z. Huang, C. Limborg, Y. Jiao, Y. Nosochkov, T. Raubenheimer, M. Woodley, W. Wan, J. Wu
![Page 57: A bunch compressor design and several X-band FELs Yipeng Sun, ARD/SLAC 2011-04-13, LCLS-II meeting.](https://reader035.fdocuments.in/reader035/viewer/2022062315/5697bf8b1a28abf838c8b188/html5/thumbnails/57.jpg)
Bunch compressionPage 57
Current less sensitive to RF phase jitter
20pC, 80 micron
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L =6 m L =9 mrf = -25°
L =330 mrf = -41°
L =550 mrf = -10°
BC-1L =6 m
R56= -36 mm
BC-2L =22 m
R56= -25 mm DL-2L =66 mR56 = 0
DL-1L =12 mR56 0
undulatorL =120 m
6 MeVz 0.83 mm 0.1 %
150 MeVz 0.83 mm 0.10 %
250 MeVz 0.19 mm 1.8 %
4.3 GeVz 0.022 mm 0.76 %
13.6 GeVz 0.022 mm 0.01 %
...existing linac
L0
rfgun
L3L1 X
LhL =0.6 mrf=-160
L2
LCLS
L = 16 mrf = -40°
L = 72 mrf = -40°
L 850 mrf = 0°
BC-2L 14 m
R56= -36 mm
BC-3L 18 m
R56= -11 mm
undulatorL =? m
6 MeVz 2.0 mm 0.1 %
120 MeVz 0.5 mm 2.0 %
375 MeVz 0.1 mm 1.4 %
1.64 GeVz 0.020 mm
0.5 %
20.5 GeVz 0.020 mm 0.01 %
L3L0
LhL =1.4 mrf= -191
rfgun C L1
BC-1L 4 m
R56= -76 mm
L = 8 mrf -22°
L2
TESLA-XFEL
(2003 parameters)
Paul Emma
![Page 59: A bunch compressor design and several X-band FELs Yipeng Sun, ARD/SLAC 2011-04-13, LCLS-II meeting.](https://reader035.fdocuments.in/reader035/viewer/2022062315/5697bf8b1a28abf838c8b188/html5/thumbnails/59.jpg)
Energy change + optics (dispersion) (2)Emittance & trajectory (slice)
For sufficiently large slice number, one can assume same energy change in one slice
Change slice emittanceChange slice trajectory
Other terms
![Page 60: A bunch compressor design and several X-band FELs Yipeng Sun, ARD/SLAC 2011-04-13, LCLS-II meeting.](https://reader035.fdocuments.in/reader035/viewer/2022062315/5697bf8b1a28abf838c8b188/html5/thumbnails/60.jpg)
CSR energy change + phase rotation (smear)Emittance & trajectory (slice)
For over-compress, CSR-process can be treated as an integral process, with continuing bunch compression (lengthening).
Change slice trajectory & emittance
Negligible