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LARP-CM10, BNL 23-25 Feb., 2008LARP-CM10, BNL 23-25 Feb., 2008 J. Byrd, Lawrence Berkeley National LaboratoryJ. Byrd, Lawrence Berkeley National Laboratory
LHC Crab Cavities: Proposed LBNL Contributions
John Byrd
LARP-CM10, BNL 23-25 Feb., 2008LARP-CM10, BNL 23-25 Feb., 2008 J. Byrd, Lawrence Berkeley National LaboratoryJ. Byrd, Lawrence Berkeley National Laboratory
LBNL Efforts• Design of HOM/LOM couplers (D. Li)
– Extensive Microwave Studio and MAFIA modeling– Possibility of experimental verification on low power
prototypes
• RF Controls (J. Byrd)– Stabilized RF phase distribution (most useful for local
scheme)– RF controller development
• Beam-beam simulations of crabbed beams (J. Qiang)– Strong-strong code to gauge benefit of various crabbing
schemes– See J. Qiang’s talk from the AP session earlier today.
LARP-CM10, BNL 23-25 Feb., 2008LARP-CM10, BNL 23-25 Feb., 2008 J. Byrd, Lawrence Berkeley National LaboratoryJ. Byrd, Lawrence Berkeley National Laboratory
HOM/LOM Coupling• Recent progress….
– Squashed cavity • Reduced magnetic field• Degenerate mode separation
– On-beam-pipe damping• Simulation and experiment shows
stub coupling promising. With an optimized stub length, get Qext~200
– On-cell damping• Field enhancement acceptable• Qext low to several tens• Need to check multipacting
– Multi-cell• Cell-to-cell coupling studied• 2-cell/4-cell structure
• Effort highly leveraged on existing programs
LARP-CM10, BNL 23-25 Feb., 2008LARP-CM10, BNL 23-25 Feb., 2008 J. Byrd, Lawrence Berkeley National LaboratoryJ. Byrd, Lawrence Berkeley National Laboratory
RF controls• Stabilized RF distribution
– Uses interferometrically stabilized optical fiber to deliver ultrastable relative RF phase (<100 fsec)
– Prototype tests at SLAC show stability of ~15 fsec over several weeks (<0.1 mrad@800 MHz)
• RF Controller– Based on long-term
development – Integral to fiber phase
distribution
• Work leveraged on existing development for light sources (LCLS, NSLS-II, Fermi@Elettra)
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LARP-CM10, BNL 23-25 Feb., 2008LARP-CM10, BNL 23-25 Feb., 2008 J. Byrd, Lawrence Berkeley National LaboratoryJ. Byrd, Lawrence Berkeley National Laboratory
Funding requests• Design of HOM/LOM couplers
– $40k labor; $30k
• RF Controls– $40k
• Beam-beam simulations of crabbed beams– $10k
• Travel – $10k
• M&S (RF controls)– $10k
• Total request: $140k