MICE- AFC UnitMechanical Design of the

Cold Mass Support System

Oxford University

Rohan Senanayake

Complete Assembly

General Arrangement of the cold mass support system

An Overview of AFC Unit

1. Cold Mass– Bobbin

– G10 Insulation

– Focusing Coils

– Cover Plate/Mounting brackets for Cold Mass

2. Copper Shield

3. End Plates and Cylindrical Core

4. Cold Mass Support System

5. Warm Vessel

Bobbin G10 Insulation Focusing Coil

Bobbin with G10 Insulation and Focusing Coils

Coil Cover Plate with Cold Mass Support Brackets Cold Mass

Cold Mass

Copper Shield

End Plates and Cylindrical Core

Cold Mass, Support System and the Warm Vessel

Section View of the Complete Assembly

Cold Mass Support System• 4 sets of Links anchored to the Cold Mass and Outer Casing to carry an Axial load on Cold Mass of 200 KN. Each link is pre-

tensioned to 50 KN when cold.

• Each pair of links is skewed relative to each other to provide torsional stiffness

• Each Link is made of 2 Glass fiber Epoxy (E-Glass) links and one stainless steel link cooled to 500K. All the links and the cold mass support system are linked through stainless steel pins.

• Anchor point on the outer casing includes a mechanism to pre-tension the links and help to align the cold mass accurately

Arrangement of the links to provide Torsional Stiffness

Vertical Plane

450 Plane

Warm Vessel/ Outer Casing

Components of the Cold Mass Components of the Cold Mass Support SystemSupport System

• E-Glass Straps• Stainless Steel Block• Stainless Steel Shear Pins• Integrated Tensioning Device/ Anchor on warm

vessel• End Cap• Mounting Bracket for Cold Mass Support

Complete Link

E Glass Strap Stainless Steel Block

Components of the Integrated Tensioning Device/ Anchor on warm vessel

The device also prevents twisting of the link during the tensioning operation.

Mounting Brackets on the Cold Mass

Integrated Tensioning Device/ Anchor on warm vessel

End Cap welded to form a vacuum tight joint.

Pre -Tension Control

T = 0.2 Fi dp

T – Torque in N-m

Fi – Tension in support link KN

dp – pitch diameter of thread mm

Tension KN Torque N-m

37.5 300

50.0 400

62.5 500

Example

One turn of the nut moves the screw (cold mass) through one pitch. Pitch of screw = 2 mm

Therefore one turn of the nut moves the corresponding mounting point of the cold mass through 2 mm

Position Control of Cold Mass

A table showing the relationships between angular and radial positions of the cold mass centre line and rotation of the adjustment nuts will be compiled. This can be used during the assembly/ setup

Summary statement

The design on the Cold Mass support system is adequate to take on the imbalance magnet force while allowing independent adjustment of the position of cold mass

Further work

Dip in the vessel shell under tension load:Manual calculations indicate a deflection of 0.5mm. A FE analysis will be done and the anchor points will be strengthened locally if necessary

Shrinkage during vacuum:Would this shrinkage reduces the pre-tension load?

Table of the adjustment of the individual cold mass support link to the positioning / alignment of the magnet.

These will be ready by the next collaboration meeting in October.