Ultimate Storage Rings PEP-X and SPring-8 II R. Hettel for the PEP-X design team and T. Watanabe et al., SPring-8 FLS 2012 JNAL March 7, 2012.

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 GeV

I = 1.5 A

ex = 150 pm-rad

(~0.06 nm-rad w/o IBS)

ey = 8 pm-rad

s = 3/6 mm(without/with 3rd harm rf)

t = ~1 h

top-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

bri

gh

tne

ss

(ph

/s/m

m2/m

r20

.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 IDs

9

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-rad

lFEL = 1 nm /4l p = 80 pm-rad

Ipk = 300 Apk LID = 50-100 m

Ppk = 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

Bri

llia

nce

Energy (keV)

4 – 6 GeV is the best

6 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 cavity

2) 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: s = 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