ultimate storage rings pep-x and spring-8 ii r. hettel for the pep-x design team
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Ultimate Storage Rings PEP-X and SPring-8 II
R. Hettel for the PEP-X design teamand T. Watanabe et al., SPring-8
FLS 2012JNAL
March 7, 2012
PEP-IISPEAR3
2 km warm linac (33 GeV) + damping rings:
PEP injectionFACETLCLS 2
LCLS injector
LCLS
1 km warm linac (16 GeV):LCLS 1
LCLS 2
What is the Future of X-ray Sources at SLAC?
PEP-X Design Study
E = 4.5 GeVI = 1.5 Aex = 150 pm-rad(~0.06 nm-rad w/o IBS)
ey = 8 pm-rads = 3/6 mm(without/with 3rd harm rf)t = ~1 htop-up injection every few seconds (~7 nC, multiple bunches)
PEP-X Baseline Concept (consolidated experimental halls)
• 2 arcs of DBA cells with 32 ID beam lines (4.3-m straights)
• 4 arcs of TME cells
• ~90 m damping wigglers• 6 ea 120-m straights for injection, RF,
damping wigglers long IDs, etc.
Same coherent flux as 11-pm USR: higher emittance and current
PEP-X: Diffraction-Limited Storage Ring at SLACEnergy 4.5-5 GeVCurrent 200 mAEmittance (x/y) 11/11 pmBunch size (x/y, ID) 7.4/7.4 mm rms†Bunch length 4 mm rms*Lifetime >2 h*Damping wigglers ~90 mID length (arc) ~4 mID length (straight) <100 mBeta at ID center, (x/y) 4.92/0.8-5 mCircumference 2199.32 mHarmonic number 3492† Vertical beam size can be reduced towards 1 mm
* Harmonic cavity system would increase bunch length to ~8 mm and double the lifetime
sufficient dynap for off-axis injection
Multibend Achromat Cells
optimizing dynap and lifetime with ELEGANT
M. Borland
7BA cell
modified from MAX-4
cancelling all 3rd and 4th order resonances except2nx-2ny
Y.Cai et al., SLAC-PUB-14785, 2011
1.E+17
1.E+18
1.E+19
1.E+20
1.E+21
1.E+22
1.E+23
0.01 0.1 1 10 100
brig
htne
ss (p
h/s/
mm
2 /mr2
0.1%
BW
)
photon energy (keV)
Brightness Envelopesnot including SC IDs
1
2
3
4
5
ALS upgrade: 1.9 GeV, 0.5 A, 195 m 2200 x 30 pm-rad, 4-4.5 m IDs
1
NSLS-II: 3 GeV, 0.5 A, 792 m600 x 8 pm-rad, 3-4 m IDs
2
MAX-IV: 3 GeV, 0.5 A, 528 m263 x 8 pm-rad, 3.8 m IDs
3
PETRA IIII: 6 GeV, 0.1 A, 2304 m1000 x 10 pm-rad, 5 m IDs
4
APS upgrade: 7 GeV, 0.18 A, 1060 m 2500* x 8 pm-rad, 4.8 m IDs
5
SDLS: 2 GeV, 0.5 A, 250 m40 x 40 pm-rad, 4 m IDs
7
PEP-X: 4.5 GeV, 0.2 A, 2200 m11 x 11 pm-rad, 4 m IDs
8
USR7: 7 GeV, 0.2 A, 3160 m15 x 15 pm-rad, 8 m IDs9
TevUSR: 11 GeV, 0.1 A, 6283 m1.3 x 1.3 pm-rad, 4 m IDs
10
7
8
9
10
USRs - Spectral Brightness
25-m ID
5-m ID
6
Cornell ERL: 5 GeV, ~3150 m30 x 30 pm-rad, 0.1 A or8 x 8 pm-rad, 0.025 A
6
6
1.E-05
1.E-04
1.E-03
1.E-02
1.E-01
1.E+00
0.01 0.1 1 10 100
cohe
rent
frac
tion
photon energy (keV)
Coherent Fraction
7 TevUSR: 1.3 x 1.3 pm
5 USR7: 15 x 15 pm
3 MAX-IV: 260 x 8 pm
6 PEP-X: 11 x 11 pm
4 SDLS: 40 x 40 pm
2 NSLS-II: 600 x 8 pm
1 ALS upgrade: 2200 x 30 pm1
2
3
45
6
7
USRs – Coherent Fraction
PEP-X Soft X-ray FEL in switched bypass
Ee- = 4.5 GeV ex,y = ~11 pm-radlFEL = 1 nm l/4p = 80 pm-radIpk = 300 Apk LID = 50-100 mPpk = few hundred kW rep rate: kHz
Can inject special short, high peak current bunch to lase for a few turns
Preliminary studies show that radiation from 50-100 m undulator whose first harmonic is tuned to < ~380 eV (> 3.3 nm) would be enhanced by one to two orders of magnitude by the SASE FEL process acting with the stored beam.
30 nm 42 eV
3.3 nm379 eV
Soft X-ray Partial Lasing with Stored Beam in PEP-XZ. Huang, C. Pellegrini et al.
Option: 2-pass with 2.5-GeV linac
PEP-X ERL – some options
• SCRF = 1.3 GHz• “bunch stealing” @ ~ 1 MHz could drive FELs
SPring-8 II
http://www.spring8.or.jp/en/about_us/whats_sp8/spring-8_II
Goal:- Significant improvement in light source performance,
especially brilliance- In 2019 with 1 year shutdown- Cost range: approx. 40 billion Japanese yen
“Boundary conditions”:- To take full advantage of existing resources
>> Reuse the existing tunnel- ID beamline hutches should not be moved.- Same X-ray spectral range : a few to 100 keV- Good stability
SPring-8 upgrade plans (from T. Watanabe)
A high-quality injection beam is needed.At SPring-8 we have XFEL Linac, which will be used as a full-energy injector to the storage ring.
Energy: 8 GeV (max.)Emittance: 40 pm.radEnergy Spread: 0.01 %Bunch Length: 30 fs (rms)Electron Charge: 300 pC – 1 nC
XFEL(SACLA)
SRBooster
Linac Parameters:(typical)
14
SPring-8 II – at-energy linac injector
1 10 100 10001017
1018
1019
1020
1021
1022
1023
1024
6 GeV 8 GeV Current
Bril
lianc
eEnergy (keV)
4 – 6 GeV is the best6 GeV is presently assumed, but 4.5-5 GeV under consideration
Intra-beam scattering (IBS)
6 GeV is better than8 GeV up to 100+ keV
SPring-8 II – electron energy
Natural emittance = 67 pm.rad
+Damping by ID'sDamping wigglerDamping partition controlCoupling controletc...
Emittance = K (Electron energy)2
(# bends)3X D
SPring-8 II – 6-bend achromat lattice
SPring-8 II – damping by IDs and wigglers
SPring-8 SP-8 II (planned)
Electron energy 8 GeV 6 GeVCurrent 100 mA ~300 mAEmitance 3.4 nm.rad 67→10 pm.radEnergy spread 0.0011 ~0.001Coupling 0.2 % ~2 %Bunch length (rms) 13 ps >20 psCircumference 1436 m 1436 m# beamlines 62 max. 62+ max.
* Parameters for SP8-II may be changed.
X 1000
Energy : 6 GeVEmittance: 35 pm.radCoupling: 2 %Energy spread: 0.1%Current: 300 mA
Brilliance: SPring- 8 vs. SPring-8 II
40ps 40ps 40ps1ps
XFEL
SP-8 II
~10 fs
Rough image:
1) ~ 1 ps, using x3.5 harmonic cavity2) Should not affect extremely small emittance bunch
Now under discussion with users
SPring-8 II – possibility of short bunch operation
※DA ~ ±3 mm
A single device that enables both on- and off-axis injections
SPring-8 II – new injection scheme
A quarter of the unit cell
Beam
Critical magnets
Need R&DNew vacuum design necessary
SPring-8 II – strong multipole magnets
SPring-8 II – new RF system
Bell-shaped(measured)
SP8-II(MAFIA)
f [MHz] 508.58 508.58
mode TM010 TM020
Q0 40000 61300
Rz [MΩ] 6.2 7.6
Rz/Q0 155 12352
0 m
m
Goal:8MΩ
Fundamental RF system
Compact design for fitting in newstraight sections.
HOMdamper
New design
Cavity forcurrentSP8
e-bunch needs to be lengthenedfor lifetime and less IBS effect
New higher harmonic RF systemenables it.
SPring-8 II – harmonic RF system
Sextupole alignment error: = 10 mm, cutoff = +/-20 mm
Dynamic aperturewith 20um SX errors
SPring-8 II – dynamic aperture
- Goal: ~10pm.rad = ultimate storage ring
- Planned for 2019 with one-year shutdown
- Take full advantage of existing resources
- Now under extensive studies for lattice design and technology developments
- Challenging issues clarified
- New components proposed and studied, but need more
- A couple of design alternatives. Open to any change.
- R&D will start in FY2012
SPring-8 II – Summary
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