The Ultimate Light Source A. Ropert, ESRF

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The Ultimate Light SourceA. Ropert, ESRF

• Outline
• Objectives
• Ultimate Storage Ring Light Source
• Alternative solutions

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The ESRF today
DBA lattice with distributed dispersion ex 4
nm, coupling 0.7 I 200 mA 43 beamlines (31 ID)
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Options for future machine upgrade

• Fulfil present and future requirements of the
  majority of ESRF users
• Maximum flux in the 5 - 50 keV energy range

• Reduction of the electron beam horizontal
  emittance, leading to a higher transverse
  coherence and an increase of the brilliance

and / or

• Increase of the number of ID beamlines

• Increase the current

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Achromat design guidelines

• Emittance dictated by the scaling law

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USRLS parameters
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The lattice
Optimisation strategy
BUT Doubling of straight sections for
RF Unavailable straight sections Power (1.2 MW
for 10 wigglers) ID technology
Use of damping wigglers ? 10 to reduce the
emittance by a factor of 2
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Alternative scenarios

• The 2 km ring may look too speculative

• What can we do in the ESRF storage ring tunnel ?

• Modification of the existing lattice

• Replacement of the storage ring by a new ring
  located in the existing tunnel

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Boundary conditions

• Same energy

• Same circumference

• Keeping untouched the existing tunnel and
  beamlines

• Length of straight sections optimised to
  accommodate 1 or 2, 1.7 m long ID segments

• Same alternating high/low bx at IDs

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Lattice feasibility (1)

• Criteria to identify critical characteristics
• of first-order optics

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Lattice feasibility (2)

• Gradient in dipoles
• Combined function magnets

Gmax 4 T/m in existing rings
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Combined function magnetsPreliminary study by
T. Perron (ESRF)
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Beam-stay clear requirementsL. Farvacque (ESRF)
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Beam-stay clear requirements (2)L. Farvacque
(ESRF)
Vertical
Main contribution from closed orbit allowance

• Requirements
• 10 coupling for injected beam
• First turn orbit control

BSC 8 mm
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Emittance reduction
Applied in several machines But moderate gain
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Lattices
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Increase of the number of straight sections
Concept already applied to several rings
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Comparison of the different options
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The double DBA structure
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Future plans (1)

• Assess the feasibility of the lattice design
• First-order optics free space between elements
• magnet gradients
• beam stay clear requirement
• Non-linear dynamics optimisation of dynamic
  aperture

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Future plans (2)

• R D work and prototyping on equipment
• Innovative combined function magnets of
  unprecedented small aperture
• HOM-free RF cavities fitting in the limited space
• Vacuum chamber and impedance
• Instability thresholds