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