Transcript PETRA III, FLASH, European XFEL: Synchrotron Light Source

FLASH 2 Beam Dynamics Issues
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DESY –MPY-
FLASH II
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FLASH II Proposal
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Principal Layout
Operation Modes
SASE operation
Seeded schemes:
HGHG operation
HHG operation
Hybrid: HHG seed with HGHG stage
EEHG under study
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Layout
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Extraction into FLASH II
• Preserve beam quality
• Simultaneous operation of FLASH & FLASH II
– Kicker – Septum extraction
– No optics changes
– R56 = 0 to have similar compression behavior
• Arc should allow for energy collimation
• Space for laser beam ‘injection’
• Foresee space for additional beamline (FLASH III)
Challenges:
• Very limited space between ACC7, extraction and collimation
• CSR induced projected emittance growth, especially important for
cascaded HGHG and HHG schemes
• See also BD meeting 2009.01.26 and others
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1st Layout of Extraction Arc
okay for SASE but to large projected
emittance growth (factor 4-8)
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Principal Solutions
• Keep bends shorter than overtaking length and try to minimize
dispersion downstream
• Avoid high betas where CSR transients still cause energy loss
• Try cancellation effects with appropriate phase advance between
bending sections
• Optimization tends to minimum emittance cell solutions
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Principal Solutions - Example
Triple bend achromat with total of 10 deg bending
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Open Questions
• Septum: Lambertson or Current-Sheet ?
• FLASH Bypass or commissioning dump ?
• Maintain FLASH collimation or move
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First Collection of Requirements (tbc)
Requirement
Specifiation
Priority
Intrabunchtrain switching
10 Hz switch with < 50 ms rise
high
Maximum Energy
1.6 GeV
high
Minimum Energy
0.5 GeV
high
Energy Bandwidth P2P
>1%
high
Max. projected emittance growth
x 2 at low energy, x 1.5 at high
to be verified
Max. energy spread
EEHG smallest, SASE relaxed
to be verified
Max. slice emittance growth
about 10%
medium
Arc geometry: total angle
8-11 deg
high
Arc gemeotry: total length to und
24 m
low
Distance Kicker Septum
6m
medium
Max. slice energy spread
Collimators (beta & energy)
high
Extraction FLASH III
high
Trans. Feedback Kickers
medium
Tuneable R56 around zero
high
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