rfq structural mods scott lawrie. vacuum pump flange vacuum flange coolant manifold cooling pockets...

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