Present status of the flux return yoke design Joint Institute for Nuclear Research Present status of the flux return yoke design A.Efremov, Yu.Lobanov, A.Makarov Torino, 16.06.2009

Magnet design

Yoke layout (new) change in positions of the spacers in the forward door for better accommodation of the muon chambers more thin axial bars (25x30 mm) between the barrel steel plates for more space for the muon counters change in the screw attachment of the end caps to the barrel absence of some connecting bars around the recesses in the upper barrel beam for insertion of muon panels

Support frame layout (new) increased distance between I-form beams of the vertical and inclined bars of the frame for the better rigidity increased dimensions of the plates coupling the I-form beams in the bars decreased (by 160 mm) distance between the rails, according to the new bars thickness inclusion of electric drive motors into the model

Support frame layout (new) View from the below

TS layout (new) Side view

TS layout (new) Side view (detail)

TS layout (new) Side view (detail)

Yoke cross-section The door halves will be screwed to each other when they are closed The end caps must be screwed to the barrel during the magnet movement Free door opening: removal of spacers + deviation of direction by 1O (TT comment #2: spacers OK, why 1O ?) The open doors are fixed in vertical position by the upper roller guide system (TT comment #2: why it is so massive?) The free space should be left for access to the screws

Yoke and support front view

2D FE model Analysis subject: Cryostat and detectors weight application points Iron yoke (distributed gravity load) The yoke weight is supported by the movable platform Analysis subject: deformation difference between different cases of support point positions (wheels, lifts and permanent supports) deformation of the platform supporting the doors Door gravity load points (when the doors are attached to the barrel during the magnet movement in the hall) The door halves are fixed to each other

Deformations due to gravity: 2 points of support Cryostat and detectors are supported by the upper barrel beam Dy = -1.6 mm H X1 X2 Support point DH = -0.95 mm DX1 = +1.2 mm DX2 = +0.7 mm The doors are supported by the side barrel beams

Deformations due to gravity: 4 points of support Cryostat and detectors are supported by the upper barrel beam H X1 X2 Support points DH = -1.6 mm DX1 = +2.1 mm DX2 = +1.1 mm The doors are staying on the rails supported by the jacks

Deformations due to gravity: 6 points of support Cryostat and detectors are supported by the upper barrel beam H X1 X2 Support points DH = -1.5 mm DX1 = +2.0 mm DX2 = +1.0 mm The doors are staying on the rails supported by the jacks

3-D model Positions of the screw connections

3-D model Cryostat and detectors weight Magnetic pressure Points of attachment to the frame displacement The load case corresponds to 4+4 points of support

3-D model View from Z-direction Cryostat and detectors weight Magnetic pressure Points of attachment to the frame displacement The load case corresponds to 4+4 points of support

3-D model Vertical deformations including the support frame DY = -3.1 mm DX = ± 1.2 mm Without support frame: DY = -8.7 mm, DX = ± 4.8 mm

3-D model Vertical deformations along the line DY = 0.09 mm

3-D model Vertical deformations along the line DY = 0.23 mm

3-D model Vertical deformations along the line DY = 0.08 mm

3-D model Vertical deformations along the line DY = 0.27 mm

3-D model Horizontal deformations along the line DX = 0.02 mm

3-D model Upper barrel beam Axial magnetic force 227 kN Magnetic pressure Cryostat and detectors weight Axial magnetic force 227 kN Connection with the adjusting beam

3-D model Upper barrel beam Axial magnetic force 227 kN

3-D model Upper barrel beam Axial magnetic force 227 kN Small contact areas

3-D model Upper barrel beam Vertical displacements DY = 0.44 mm

3-D model Upper barrel beam Vertical displacements (detail)

3-D model Upper barrel beam Buckling analysis 1-st mode n = 24.5 (safety margin)

3-D model Upper barrel beam Buckling analysis 2-nd mode n = 27 (safety margin)

Summary The relative deformations of the yoke during the movement in the framework of the considered concept of the platform (4 pairs of the railing wheels) are about 2 mm. The deformations in 3D and 2D models do not differ much The deformations for support systems with 4 or 6 jacks are almost equal The suspension system for cryostat and detectors should be designed so that their positions would not critically depend on the yoke deformations The change of the distance between the upper and lower barrel beams must be taken into account for design of the target pipe connecting the Target Production, IP and Target Recovery systems In order to ensure the rails supporting the doors to be straight-line (for the unhindered door sliding), the supports for them in the experimental hall should be provided (in addition to the jacks supporting the main platform) The contact area between the upper beam and the downstream door is small (the stress is 90 MPa), so increase of the recess in the beam is not allowable Stability analysis of the magnet on the jacks, including seismic mode - ?