RFQ Structural Mods
Scott Lawrie
Vacuum Pump Flange
Vacuum Flange Coolant Manifold
Cooling Pockets Milled Into Vanes
Potentially Bolted Together
Tuner & Coupler Ports
Vanes
Increased Pumping Area
Original design: Twelve 12mm wide slotsPumping area = 7045 mm2
Modified design: Four 25mm wide slotsPumping area = 9749 mm2 (43% greater)
Simulation Bodies
25mm12mm
Section of pump’s debris-catching grill
Inter-vane vacuum
Bulk quadrant vacuum
Pumping slot vacuum
Magnetic Field Results
B-field plot path
≈1W total heat
≈10mW total heat
Turbo-pump grill position
B-field along plot path
Because B-field is not uniform, neither is heat load.Therefore 1W is an over-estimate, but let’s not push it!
Magnetic Field Across Grill
Assume 1mm pitch, square wire grill
Frequency varies with RFQ lengthMode Frequency / MHz
LC
10
Resonant Frequency:
Superfish
Present geometry
Q = 12463Shunt Impedance = 2830 MΩ/mPower/Quadrant/cm = 186 W
Increased quadrant radius to bring on tune
Q = 12749Shunt Impedance = 3022 MΩ/mPower/Quadrant/cm = 174 W
Reduced quadrant radius but increased vane width
Q = 11504Shunt Impedance = 2308 MΩ/mPower/Quadrant/cm = 228 W
20mm wide vanes allow:
1.More material, so greater thermal conductivity and strength2.Easier to machine straight edges3.More room for cooling pocket penetration toward vane tip
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