A DDBA lattice upgrade of the Diamond ring R. Bartolini, C. Bailey*, - - PowerPoint PPT Presentation

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A DDBA lattice upgrade of the Diamond ring R. Bartolini, C. Bailey*, - - PowerPoint PPT Presentation

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A DDBA lattice upgrade of the Diamond ring R. Bartolini, C. Bailey*, M. Cox*, N. Hammond*, R. Holdsworth*, J. Kay*, J. Jones**, E. Longhi*, S. Mhaskar*, T. Pulampong, G. Rehm*, R. Walker* John Adams Insititute and *Diamond Light Source **

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SLIDE 1

A DDBA lattice upgrade of the Diamond ring

  • R. Bartolini, C. Bailey*, M. Cox*, N. Hammond*, R. Holdsworth*, J.

Kay*, J. Jones**, E. Longhi*, S. Mhaskar*, T. Pulampong, G. Rehm*, R. Walker* John Adams Insititute and *Diamond Light Source ** ASTeC/Cockcroft Institute

3rd Low Emittance Ring Workshop Oxford, 8 July 2013

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SLIDE 2

Outline

  • Diamond upgrade plans

MBAs options considered Tools used for optimisation DDBA lattice and its evolution

  • Cell2 modification for VMX beamline

AP and ID performance Design issues targeting VMX

  • Technical subsystems (requirements, challenges and WIP)

magnets (see C. Bailey’s talk on Tuesday) engineering integration (see N. Hammond’s talk on Wednesday) vacuum, RF, diagnostics, …

  • Future work

3rd Low Emittance Ring Workshop Oxford, 8 July 2013

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SLIDE 3

Emittance in 3rd GLS, DR and B-factories

Transverse coherence requires small emittance Diffraction limit at 0.1 nm requires 8 pm

    4

~ 2013

' y y ' x x 2

4       flux brilliance

2 ph 2 e x x

    

, 2 ph 2 e x x

'

, ' '

    

2 x x x x

) D (

     

2 x x x x

D ) ' (

' 

         4 Lu

ph  u ph

L    '

?

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SLIDE 4

MAX IV 7BA 3 GeV 320 pm 500 mA SS length 5m DA 7mm w/errors Sirius 5BA w/superbend 3 280 500 5m & 6m 5 mm w/errors Spring-8 6BA 6 67.5 300 4.5m & 27m 3 mm w/errors APS 7BA 6 147 100 Pep-X 7BA 4.5 11 200 5 m 10 mm w/errors ESRF Phase II 7BA 6 130 200 5m 10 mm SOLEIL QBA w/longit.. gradient dipole 2.75 980 (220) 500

  • Robins. Wiggler +

beam adapter Diamond

  • mod. 4BA,

5BA, 7BA 3 45-300 300 5m & 7 m 2 mm ALS 5BA - 7BA 2 50-100 500 5 m 2-3 mm BAPS 7BA-15BA 5 50 150 10m & 7m 10 mm w/errors tUSR 7BA 9 3 100 TEV tunnel 0.8 mm

Survey of low emittance lattices (Beijing Nov. 2012)

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SLIDE 5

Lattice design at Diamond

  • Initial criteria

Reuse tunnel and beamlines Reuse as much hardware as possible Phased installation (avoid long shutdown)

  • Evolution of MBA design

Initial low emittance lattice design used standard MBA cells M = 7, 6, 5 and 4 It transpired that a 4BA cell can be modified to introduce an additional straight in the middle of an arc (a generalisation of SOLEIL’s approach*) while keeping the dispersion small and the emittance small

3rd Low Emittance Ring Workshop Oxford, 8 July 2013

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SLIDE 6

Lattice design at Diamond

Early studies with MBAs

3rd Low Emittance Ring Workshop Oxford, 8 July 2013

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SLIDE 7

Original DBA 5BA

5BA and 7BA fitting Diamond cell length

Original DBA 7BA

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SLIDE 8

5BA optimisation

Driving term compensation after 4 cells

Fourth order and detuning terms much harder to compensate

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SLIDE 9

MOGA sumDiff + sumRDTs using harmonic sextupoles; chromaticity (2,2)

DA optimisation

3rd Low Emittance Ring Workshop Oxford, 8 July 2013 The optimisation of the DA and lifetime is an iterative process that involves Linear optic matching and working point selection RDT analysis, FM and detuning curve check MOGA DA achieved (WIP) 4BA DA 5 mm 5BA DA 3.5 mm 7BA DA 1 mm

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SLIDE 10

IBS emittance blow-up as a function of stored current coupling 10% 900 bunches – computed with elegant

4BA H emittance

IBS emittance increase

3rd Low Emittance Ring Workshop Oxford, 8 July 2013

5BA H emittance 7BA H emittance

4BA lattice 265 pm  280 pm @ 300 mA relative increase 6% 5BA lattice 140 pm  180 pm @ 300 mA relative increase 29% 7BA lattice 45 pm  90 pm @ 300 mA relative increase 100%

300 mA 300 mA 300 mA

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SLIDE 11

Lattice design at Diamond

4BA

3rd Low Emittance Ring Workshop Oxford, 8 July 2013

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SLIDE 12
  • Increase dispersion at chromatic sextupoles
  • Optimize magnets positions and length leaving more distance between dipoles

(no coil clash)

  • removed sextupoles in the new straight
  • Longer mid-cell straight section from 3m to 3.4 m – longer is unmanageable

A 4BA lattice for Diamond-II

  • riginal DBA cell

3rd Low Emittance Ring Workshop Oxford, 8 July 2013

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SLIDE 13

This lattice combines the ideas of doubling the capacity of the ring with the low emittance

Parameters Modified 4BA Circumference [m] 561.0 Emittance [pm.rad] 275 Tune Point [Qx / Qy] 50.76/18.36 Chromaticity(ξx / ξy)

  • 128/ -94

straight sections [m] 9.1 / 6.7 / 3.2 Momentum compaction 1.02e-04 Bunch length [mm] 1.77 Energy spread (rms) 7.94e-4 Damping time h/v/s [ms] 14.78/19.60/11.70 Energy loss/turn [MeV] 0.573

A 4BA lattice for Diamond-II

3rd Low Emittance Ring Workshop Oxford, 8 July 2013

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SLIDE 14

Optimisation (I): driving terms

Qx: 4.5 /cell Qy: 0.775*2 /cell 1 superperiod i.e. 4 cells give (2n)pi All first terms cancellation within 1 super period Cell phase advance adjusted to compensate 1st order RDTs Chromaticity set to (2,2): detuning terms still large; higher order resonances still large 3rd Low Emittance Ring Workshop Oxford, 8 July 2013

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SLIDE 15

DA still below 5 mm – under optimisation

Optimisation (II): Multi-objective GA for DA

3rd Low Emittance Ring Workshop Oxford, 8 July 2013

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SLIDE 16

Lattice design at Diamond

One (or more) modified 4BA cells in the present lattice (to be called DDBA)

3rd Low Emittance Ring Workshop Oxford, 8 July 2013

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SLIDE 17

One DDBA cell in the existing lattice

DDBA cell

Replacing the existing cell2 with a DDBA cell

  • Introduces an additional straight section

(bending magnet beamline upgraded to ID beamline)

  • Serves as a prototype for low emittance

lattice upgrade

  • In line with phased upgrade
  • Lots of R&D required (magnet design

challenging, vacuum with small apertures, engineering integration, etc)

Additional straight

3rd Low Emittance Ring Workshop Oxford, 8 July 2013

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SLIDE 18

Cell 2 upgrade for VMXi-VMXm

VMXm VMXi 3rd Low Emittance Ring Workshop Oxford, 8 July 2013

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SLIDE 19

ID performance

(courtesy EL)

VMXi moved from the side branch to the middle of the straight 2

2 m U21 in-vac 0.7 m U30 ex-vac 3rd Low Emittance Ring Workshop Oxford, 8 July 2013

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SLIDE 20

Ring optics with and without the DDBA cell in cell2

3rd Low Emittance Ring Workshop Oxford, 8 July 2013

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SLIDE 21

Parameters Emittance [m-rad] Tune x Tune y Chromaticity Lifetime [h] 2.5e-9 28.18 13.29 2,2 27 (29)

One DDBA: dynamic aperture and lifetime with MOGA

3rd Low Emittance Ring Workshop Oxford, 8 July 2013

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SLIDE 22

Fight for space

A constant priority in the AP design has been the safeguard of the maximum length in the new mid-cell straight section

  • Mid-cell length increased from 3m to 3.2m to 3.4m – 3.5m proved unworkable
  • pushing magnets apart, merging quads
  • corrector magnets with special design
  • coil overhang of magnets
  • Shortening of ID vessel to maximise ID length: e.g. flexible taper length

3rd Low Emittance Ring Workshop Oxford, 8 July 2013

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SLIDE 23

Saving space: merging quads

3m 3.35m 3.35m

4BA_1 Original DBA

3.35m 3 m 3.35m

4BA_2 4BA_3

3.2m 3.4m 3.35m 3.35m

3rd Low Emittance Ring Workshop Oxford, 8 July 2013

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SLIDE 24

Fight for space: 9cm H/V embedded correctors

3rd Low Emittance Ring Workshop Oxford, 8 July 2013

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SLIDE 25

Saving space: reducing flexible taper length

3rd Low Emittance Ring Workshop Oxford, 8 July 2013

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SLIDE 26

(half) DDBA cell

3.4m mid-cell straight 55 T/m 15 cm 65 T/m 20 cm

  • 14 T/m

66cm

  • 15 T/m

96cm 55 T/m 15 cm 50 T/m2 20 cm

Challenging magnets which require a small bore radius (15mm) but no showstoppers ! Other projects have much more agressive requirements Even if the minimisation of the emittance is not a primary target, the tight control of dispersion and beta functions requires very strong quads

3rd Low Emittance Ring Workshop Oxford, 8 July 2013

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SLIDE 27

Magnets for USR (Beijing November 2012)

Diffraction limited emittance requires magnets with unprecedented strength in storage ring. High gradient and high precision required quadrupole gradient MAX IV has 40.0 T/m ESRF 100 T/m Spring8-II 80 T/m BAPS 50 T/m  USR 90 T/m quadrupoles in dipoles MAX IV has 9 T/m ESRF 30 T/m sextupoles MAX IV has 4000 T/m2 ESRF- USR 7000 T/m2 Spring-8 II 13000 T/m2) BAPS 7500 T/m2 space between magnets (hard edge) 10 cm MAX IV has 2.5 cm Apertures = 20-26 mm diameter in arcs MAX IV inner diam. 22 mm 3rd Low Emittance Ring Workshop Oxford, 8 July 2013

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SLIDE 28

Ring optics with and without two DDBA cells

3rd Low Emittance Ring Workshop Oxford, 8 July 2013

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SLIDE 29

Parameters Emittance [m-rad] Tune x Tune y Chromaticity Lifetime [h] 2.55e-9 29.18 13.30 2,2 8.2 (23.h)

Two DDBAs: dynamic aperture and lifetime with MOGA

3rd Low Emittance Ring Workshop Oxford, 8 July 2013

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SLIDE 30

Conclusions

Diamond is investigating a full ring upgrade for Diamond – II Various MBA options are under analysis. We concentrated on a modified 4BA (DDBA) that doubles the capacity and reduces the emittance by a factor 10. Feasibility studies for the cell2 upgrade to a DDBA cell are promising

  • AP-wise the design is feasible
  • Many technical subsystems prove challenging but no showstoppers have been

identified (magnets, vacuum, engineering integration, diagnostics,. …)

  • Benefit for ID performance are noticeable

Underpins R&D for the full upgrade. Significant further detailed design is needed, as well as R&D for vacuum vessel fabrication and NEG coating Costing exercise is underway but the project has been fully supported from a technical point of view. 3rd Low Emittance Ring Workshop Oxford, 8 July 2013