Emittance Gymnastic Studies P.Raimondi On behalf of the Accelerator - - PowerPoint PPT Presentation

Emittance Gymnastic Studies

P.Raimondi On behalf of the Accelerator and Source Division ESRF June 15,2012

Outline

• Introduction to 4th generation SR
• ESRF toward a 4th generation SR
• ASD Short and Mid term path
• Conclusions

2

The 4th Generation SR

The last few years have been characterize by a World-Wide R&D carried

• n by Accelerator Engineers to find solutions to improve the SR beam

parameters. The Science in general benefits by any of this improvements:

• Horizontal Emittance
• Vertical Emittance => Diffraction Limit reached routinely everywhere
• Bunch Length => Very costly solutions (e.g. SC Crab Cavities)
• Energy Spread => No solutions exists for a significant decrease

(< 0.05-0.1%) in SR

• Beam Current => Close to the limits imposed by the BL

3

Low Horizontal Emittance SR

The most immediate advantages of such machines are:

• Brigthness Increase while maintaining the same flux
• Spacial Resolution Increase
• Transverse Coherence

The first two points improve almost linearly for an emittance decrease from 2-4nm down to 50-100pm. For lower emittance the gain become less than linear due to:

• the diffraction limit
• mismatch of the electron beam with the X-Ray beam

The coherence starts to be of significance for emittances below 5-10pm. For example: @10KeV 80% coherence needs about 1pm emittance.

4

J.Chavanne

5

Brilliance at lower horizontal emittance

Electron beam: 6.039 GeV I=0.2 A

• Hor. Emittance [nm]

4 0.15 0.01

• Vert. Emittance [pm]

3 2 2 Energy spread [%] 0.1 0.09 0.09 Betax[m]/Betaz [m] 37/3 6/2 6/2

10

20

10

21

10

22

10

23

Ph/s/0.1%bw/mm

2/mr 2 4 5 6 7 8 9

1 keV

2 3 4 5 6 7 8 9

10 keV

2 3 4 5 6 7 8 9

100 keV Photon Energy [eV]

6 m Undulators , min. gap=11 mm (U35, HU88) 4 m In-Vacuum undulators, min. gap=6 mm (IVU22, CPMU18)

~ x 25 ~ x 5

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

coherent fraction 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 pm 1 2 3 4 5 6 7

USRs – Coherent Fraction

Brilliance vs Hor. Emittance & Energy Spread

J.Chavanne

7

1.0x10-3 0.8 0.6 0.4 0.2 Relative Energy Spread [] 0.01

2 3 4 5 6 7

0.1

2 3 4 5 6 7

1

2 3 4

Horizontal emittance [nm]

120 100 80 60 40 30 20 10 5 2

1.0x10-3 0.8 0.6 0.4 0.2 Relative Energy Spread [] 0.01

2 3 4 5 6 7

0.1

2 3 4 5 6 7

1

2 3 4

Horizontal emittance [nm]

500 3 2 1 5 100 80 60 40 30 2 10 5 2

Fundamental (n=1) Harmonic # 9 ESRF today =1 Undulator: CPMU18, L=4m Betax=4.5m, betaz=2.5m No dispersion Vertical emittance= 3pm

8

All solutions to Lower the SR Horizontal-Emittance are based on this formula!

PEP-X 40pm@4.5GeV Multibend Achromat Cells

• ptimizing dynap and lifetime

with ELEGANT

• M. Borland

7BA cell

modified from MAX-4

cancelling all 3rd and 4th order resonances except 2nx-2ny

Y.Cai et al., SLAC-PUB-14785, 2011

ESRF toward a 4th Generation SR

The world wide effort in lattice design and technology developments has paved the road the possibility of studying options to upgrade the ESRF storage ring lattice in

• rder to significantly lower (by a factor 20-40) the equilibrium horizontal, within the

constraints underlined in the ESRF “purple book” (par. 3.1.8), in particular:

• Maintain as much as possible unchanged the existing Straight Sections and

BeamLines

• Maintain the present Injection Scheme and Injection Complex
• Reuse as much as possible the existing ARCs hardware (Power Supplies,

Vacuum System, Diagnostic etc…)

• Reduce Operation Costs, specifically Wall-Plug Power.

These constraints pose limits to the ultimate ring performances and raise technical and logistic challenges. On the other end they are consistent with the following crucial points:

• Cost comparable with a “Phase II” budget expenditure
• Upgrade to be completed by beginning of next decade (2020)
• Less than 1 year ShutDown for installation and commissioning

10

Present ESRF lattice

• L. Farvacque

11 03/05/2012

5 10 15 20 25 10 20 30 40 50 60 s [m] b [m] nx= 2.277 1 period nz= 0.837 C= 52.774 0.1 0.2 0.3 0.4 0.5 0.6 h [m] bx bz hx

Low emittance:

Careful tuning of 𝛾x and 𝜃x in the dipoles (where the radiation occurs) 𝛾x: envelope function 𝜃x: dispersion

Present ESRF lattice

• L. Farvacque

12 03/05/2012

5 10 15 20 25 10 20 30 40 50 60 s [m] b [m] nx= 2.277 1 period nz= 0.837 C= 52.774 0.1 0.2 0.3 0.4 0.5 0.6 h [m] bx bz hx

ex = Kg 2q 3

K: lattice dependent 𝛿: electron energy 𝜄: bending angle

Low emittance:

Careful tuning of 𝛾x and 𝜃x in the dipoles (where the radiation occurs) 𝛾x: envelope function 𝜃x: dispersion

Present ESRF lattice

• L. Farvacque

13 03/05/2012

5 10 15 20 25 10 20 30 40 50 60 s [m] b [m] nx= 2.277 1 period nz= 0.837 C= 52.774 0.1 0.2 0.3 0.4 0.5 0.6 h [m] bx bz hx

ex = Kg 2q 3

K: lattice dependent 𝛿: electron energy 𝜄: bending angle

Low emittance:

Careful tuning of 𝛾x and 𝜃x in the dipoles (where the radiation occurs) 𝛾x: envelope function 𝜃x: dispersion

• Increase the number of cells
• Put more dipoles per cell

Emittance reduction ⇒

New lattice

03/05/2012

• L. Farvacque

14

5 10 15 20 25 10 20 30 40 50 60 s [m] b [m] nx= 2.277 1 period nz= 0.837 C= 52.774 0.1 0.2 0.3 0.4 0.5 0.6 h [m] bx bz hx

ex = 4 nm

DBA

New lattice

03/05/2012

• L. Farvacque

15

5 10 15 20 25 10 20 30 40 50 60 s [m] b [m] nx= 2.277 1 period nz= 0.837 C= 52.774 0.1 0.2 0.3 0.4 0.5 0.6 h [m] bx bz hx 5 10 15 20 25 10 20 30 40 50 60 s [m] b [m] nx= 4.729 2 periods nz= 1.725 C= 52.801 0.1 0.2 0.3 0.4 0.5 0.6 h [m] bx bz hx

ex = 4 nm ex = 0.13 nm

DBA 7-bend achromat

• Cell packed with magnets
• Stronger focusing: tunes

36.44/13.39 → 75.66/27.60

• Chromaticity:
• 130/-58

→

• 102/-75
• Smaller 𝛾 functions

Chromaticity correction needs

• Smaller dispersion

stronger sextupoles

• Less radiated power (x2 less)

New lattice

03/05/2012

• L. Farvacque

16

5 10 15 20 25 10 20 30 40 50 60 s [m] b [m] nx= 2.277 1 period nz= 0.837 C= 52.774 0.1 0.2 0.3 0.4 0.5 0.6 h [m] bx bz hx 5 10 15 20 25 10 20 30 40 50 60 s [m] b [m] nx= 4.729 2 periods nz= 1.725 C= 52.801 0.1 0.2 0.3 0.4 0.5 0.6 h [m] bx bz hx

ex = 4 nm ex = 0.13 nm

} ⇒ {

DBA 7-bend achromat

Preliminary features:

• 2 dipole families
• 1 with gradient
• 7 quadrupole families
• 2 sextupole families
• ID straight:

5 m long instead of 7.84 m (in “6 m” section)

• No more alternating high-

and low-𝛾 sections

New lattice

03/05/2012

• L. Farvacque

17

5 10 15 20 25 2 4 6 8 10 12 14 16 18 20 s [m] b [m] nx= 2.364 1 period nz= 0.863 C= 26.400 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.1 h [m] bx bz hx

Electron beam size [µm] ESRF New High-𝛾 412 28 Low-𝛾 50 Electron beam divergence [µrad] ESRF New High-𝛾 11 5 Low-𝛾 107

New Lattice

03/05/2012

• L. Farvacque

18

• Weak bending magnet with strong gradient
• Equivalent to a quadrupole of 33 T/m offset by 1.5 cm
• Strong quadrupoles
• Strong sextupoles
• Dynamic aperture comparable (factor 1-3 smaller) with

the present lattice

• Chromatic correction made with “standard”sextupoles
• Total bend length more than doubled => energy lost

in synchrotron radiation halved

ESRF New lattice Dipole [T] 0.86 0.49 Quadrupole [T/m] 17 (25) 112 Sextupole [T/m2] 460 1650

19

Quadrupole Magnet Design G> 100T/m

EM quadrupole PM quadrupole Solutions Compatible with a “Soleil-type Vacuum Chamber”

New Lattice Engineering

The complexity of the problem is relatively contained, since it is limited only to the design of a 25m long Arc (*32). However the technical aspects are very challenging:

• High gradients magnets (4 times more)
• Tight tolerances (2 times more)
• Small vacuum chamber (2 times less)
• Very compact design

It should be stressed that the 4th Generation SRs take advantage of all the R&D and Know-How accumulated in the last 20 years at ESRF and the rest of the world:

• Lattice design
• Vacuum technologies (e.g. NEG coating that allows the use of smaller vacuum

chambers)

• Magnet technologies (better modeling and manufacturing)
• Diagnostic (e.g. Libera BPMs)
• Controls
• Operations
• …

20

Short and Mid Term path

The ASD has been working very hard in all the machine subsystems in order to improve the performances and reliability of the source. There are a lot of tasks planned for the next few years that, together with what already done will virtually complete most of the envised “Phase-I” upgrades. In order to define a mid term strategy we must consider that a big extend of what has been done so far for Phase-I and the remaining activities are synergic and/or essential for a more radical upgrade of the SR. In particular, the much more demanding SR parameters do require:

• High level of control/diagnostic/stabilization (e.g.: Libera-BPMs, FOC etc)
• HOM-damped RF-Cavities (to allow operation with shorter bunches: 5-10ps)
• TOP-UP (even with the same Dynamic-Aperture of the present ring Tau<2-5hrs)
• Improved reliability
• Smaller Gap/shorter period Undulators (to take full advantage of the increased

vertical stay-clear

• ...

21

Short and Mid Term path

In the next 2-4 years we will continue all the already foreseen activities. In particular:

• TopUp
• HOM-Damped Cavities
• 7m/Low-Beta Section

are an essential part of any possible SR Lattice Upgrade. The amount of effort/FTEs/Budget to be dedicated to a New Lattice Design and related R&D, remains to be defined. Anyway ESRF-Divisions/Groups have enough resources to progress on the studies, without impacting the present activities, at least up to a white-paper stage.

22

7m Section

Initial rationale for the 7m was to install more RF/Undulators in the straight sections. BD Group conceived the possibility of utilizing the 7m to create 2 low-ybeta points in the middle of the undulators: max vertical beta in the undulators decreses by a factor 2-3 The 7m Section will be also the test bench for:

• Studying the possibility to further decrease the Undulators Gap

(6mm=>4mm) and period (18mm=>14.6mm )(Not on ID23 b.t.w.)

• Acquire experience and Know-How on replacing ARC girders. This is the

foreseen way to upgrade the ARC lattice.

23

7 metres coordination meeting -- March 8th, 2012 24

5 metres

Qd6 S22 S24 QF7 Qd8 Qd6 S24 QF7 Qd8 S22

7 metres

Infra Red beam port bpm bpm

7 metre

3 single cell cavities

C C C

QF7_HG

Short Girder

QD6_HG S22_IR S24_200

Infra Red beam port bpm Short CV15 NEG bpm

QF7_HG

Short Girder

QD6_HG S24_200 S22

bpm Short CV3 NEG bpm

C

ID 1.6 m

C

New canting magnets +specific supports Same undulator shifted min gap +0.7 mm

2160 mm10.7mm alu_ID CV

Downstream transition CV ID 1.6 m

C C

2160 mm10.7mm alu_ID CV

New canting magnets + specific supports Same undulator shifted min gap +0.7mm Up stream transition CV

Mini beta test Short CV3 NEG Complement CV

Down&up stream transition CV QD_low

Future Standard 7-m SS23

D x =0.035m βx=0.5m βy=3.02m Qx =36.44 εx=4.0 nm

Possible mini-beta in the 7-m SS23

D x =0.05m βx=0.6m βy=1.00m Qx =36.44 εx=4.0 nm

Reducing minimum gap for IVUS

J.Chavanne 27

10

18

10

19

10

20

Ph/s/0.1%bw/mm

2/mr 2 7 8 9

10 keV

2 3 4 5 6 7 8 9

100 keV Photon Energy CPMU Undulators, L=2 m Present Low beta Straight U18, Min gap 6 mm, Kmax=1.67 Mini Betaz U14.6 Min gap 4 mm,Kmax=1.67

Conclusions

ESRF has maintained the leadership on SR facilities for more than 20 years thanks to the constant effort to improve all the facility subsystems and explore new ideas and develop original solutions. There is a very clear path to further boosts its performances in the next few years and pave the road for a quantum-leap toward a 4th generation source. Thanks all for your attention…..

28