mike neubauer muons, inc
DESCRIPTION
RF System for an HCC All the critical RF concepts have been suggested for SBIRs at one time or another by Milorad Popvic, Al Moretti, Mohammad Alsharo’a, and Mike Neubauer. Mike Neubauer Muons, Inc. Assumptions. Individual cavities are fed with RF for an HCC - PowerPoint PPT PresentationTRANSCRIPT
Mike Neubauer Muons, inc. MCDW BNL Dec 1-3
Muon Collider Design Workshop 1
RF System for an HCC All the critical RF concepts have been suggested for SBIRs at one time or another by Milorad
Popvic, Al Moretti, Mohammad Alsharo’a, and Mike Neubauer
Mike NeubauerMuons, Inc.
12/2/2009
Mike Neubauer Muons, inc. MCDW BNL Dec 1-3
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Assumptions
• Individual cavities are fed with RF for an HCC– In general, the more the cavities per HCC period,
the less the RF input power per cavity– The coax feed into the cavity can use 50% of the
length of a single cavity module or cell.– Each cavity has its own RF source phase matched
to its neighbors.• Magnet Coils fit around the outside diameter
of the cavity wall.
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Assumptions, continued
• Ceramic loaded cavities will reduce the OD of the cavity. – The drawings show ceramic loading of one style, but
there are different ways to load the cavity.• Grids are an optimum choice for the use of high
pressure gas in the HCC.– They will be shown, but other choices can be made.
• The RF system that is used to feed each individual module of the HCC is not shown.
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Cavity Module Concept• Single pill-box cavities are made
that are aligned to create an HCC. • Each Cavity has it’s on set of
magnet coils at 50% fill factor along the length of the cell
Magnet coils
Pill box cavity
Coaxial Feed
Grid Window
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An Example of Cavity DetailFormed
Grid
Plated Copper
Ceramic Filled Cavity
Magnetic Coupling
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Ez as a function of Radius for various ceramic loaded 325 MHz “pillbox” cells
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0 5 10 15 20 25 30 35 400.00E+00
1.00E-01
2.00E-01
3.00E-01
4.00E-01
5.00E-01
6.00E-01
7.00E-01
8.00E-01
9.00E-01
1.00E+00
Ez as a function of R for various ceramic loading schemes
Radius, cm
Nor
mal
ized
Ez
No ceramic
Zshunt= 6 54 100 MW/m
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Input Power per Cell (neglecting ceramic losses)
• Pin(v/m)=[V(v/m)]2/Zshunt(MW/m)
• Pin=252/Z for 25MV/m gradient• For copper at RT Z=54 MW/m for an
“optimum” ceramic loaded cavity– Pin=11.6 MW/m or 463 kw per cell
• At 70K, Z ~4.5*ZRT due to copper Ploss
– Pin=2.55 MW/m or 102 kw per cell
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Ceramic Losses
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50 100 150 200 250 3001.00E-05
1.00E-04
1.00E-03
Loss Tangent of Alumina Ceramics as a function of temperature
sapphireWESGO "warm"Friatec "warm"WESGO "cold"
Temperature, K
Loss
Tan
gent
For full ceramicloaded cavity Q=1/tandQ70K~20,000Copper onlyQ70K~100,000
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Complete HCC---Single Period
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Cavity Detail• Ceramic Loaded Cavity reduces size
– Need to verify losses at operating temperature– May need charge dissipative coating on surface seen by the beam
(currently working on a related SBIR)• Copper Plated and Post-machined
– Removes the problem of packaging and voids between ceramic and metal
• Flat moly grid anchored by ceramic ring solves distortion problems. (Puts grid in tension going down to 70K)– Ceramic ring adds mechanical support
• Coaxial Feed can be reduced in size– Need to measure power capability in High Pressure Gas
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This is a 25 cavity per period 400 MHz design
• Approximate Diameter at the coax flange is 40”
Magnet Coil
Pill box Cavity
Coax Feed per
cavity12/2/2009
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Summary
• A conceptual design for putting RF through coils into an HCC is presented.
• Engineering Design issues need to be resolved, and there do not seem to be any “impossible” constraints.
• The most important aspect is: 50% of the cavity module is enough room for an RF coax feed.
• All the critical RF concepts have been suggested for SBIRs at one time or another by Milorad, Moretti, Mohammad, and Neubauer.
12/2/2009