EuroCirCol: 16T dipole based on common coils (DRAFT) T. Martinez, J. Munilla, F. Toral - CIEMAT FCC Week, April 13th, 2016
Outline Introduction 2-D magnetic design 2-D mechanical design 2
Introduction (I) The common coil layout is based on two flat coils. A unique support structure for two apertures, placed at the same vertical plane. Main advantage: pure flat coils. Disadvantages: large stored energy and electromagnetic forces, assembly. Traditionally, American labs (BNL, LBNL, Fermilab) have worked on this layout, even for high fields. Chinese colleagues (IHEP) are working on a 20-Tesla dipole design based on common coils. In the framework of EuroCirCol project, CIEMAT is working on a 16-Tesla dipole design based on common coils. Courtesy R. Gupta (BNL) 3
Introduction (II) The starting parameters are common for the three design options under study (cos-theta, block and common coil): 4
2-D magnetic design The influence of a number of parameters has been analyzed to optimize the 2-D magnetic design and to better understand the sensitivity factors: Intra-beam distance. Iron outer diameter. Nominal current. Cable: number of strands, strand diameter. Number of coils. Magnet protection. 5
2-D magnetic design: intra-beam distance A short intra-beam distance implies a strong cross-talk between apertures: The superconductor efficiency decreases. The field quality is very difficult to achieve. 6
Outline Introduction 2-D magnetic design 2-D mechanical design 7
Overview 8
General remarks Magnetic forces calculation: Ansoft Maxwell Imported to structural Ansys Mechanical Wires modelled in Ansoft “Coil” material for each stack of wires on Ansys 9
General remarks Mechanical feasibility of a Common Coil design has been analyzed. Internal grading version of the magnet is considered the baseline option Mechanical properties for materials from previous agreements. Stress limit (MPa) 293/4 K E (GPa) P α (293 to 4.2 K) Coil 150 200 Ex=52 Ey=44 Gxy=21 0,3 X=3,1e-3 Y=3,4e-3 316LN 350 1050 193 210 0,28 2,8e-3 7075 480 690 70 79 4,2e-3 Iron 180 720 213 224 2,0e-3 Titanium 800 1650 130 1,7e-3 10
Coils Coils are modeled according two different assumptions: Whole Package made of mean coil material Coil blocks made of Coil material All coils are bonded together Coils are just supported by frictionless supports Supports include keys for horizontal and vertical preload Aluminum shrinkage is around iron Loaded cases: Assembly Cool down (4,2 K) Magnet ON – 16 T Magnet ON – 18 T 11
Iron and Shell Different Iron configurations are being studied: Split in vertical or horizontal axis Alternative arrangement of iron (vertical/horizontal) Aluminum shrinkage (cylindrical) is included, value of initial clearance is under evaluation Values of preload and clearance of V & H keys under study Improved stiffness is being studied by different possibilities, including for example by two-halves SS cylinder 12
First Results Horiz. Stress Vert. Stress Good news: Coils stresses: < 200 MPa @16 T (Sligthly higher @18T) Main challenges: Big displacements in the coils Iron stresses Results considering symmetry in x edge for iron 13
Challenges: Coils Displacement Horiz. Displ. (mm) Vert. Displ. (mm) Total displacement in the order of mm in x axis It includes small rotation of coils Not enough lateral stiffness from iron and shell to withstand magnetic forces Several approaches are being studied to reduce this effect Shell deformation (enlarged) 14 Results considering symmetry in x edge for iron
Challenges: Iron Iron (Von Misses): 16T @ 4,2K Von Mises = 736 Mpa Max. Prin. Stress = 232 Results considering symmetry in x edge for iron 15
Conclusions 2D Mechanical model for Common Coil is being studied (Internal grading) is included Mechanical design seems to be feasible for this kind of magnet, but more work is needed Assembly tolerances are being included The coil is considered completely bonded Contacts between coil and supports are frictionless Effect of manufacturing processes on contacts, gaps, not included Axial support for 3D structure is not considered yet 16