Modular coil winding form EM analysis 13 model

Modular coil winding form EM analysis 1/3 model, cover 120 degree (totally 18 coil forms) Air z 6 coil forms (1/3 model) Material: stainless steel (80 K) A 1 A 2

Modular coil winding form EM analysis 1. Coil form mesh size: 2”. 2. Stainless steel resistivity at 80 K: 65 e-8 ohm-m. 3. Time step: 0. 3 ms. 4. Poloidal cuts by modifying elem material property, to simplify the modeling. A 1 B 2 A 2 C 1 B 1 Poloidal cuts Welding Material: stainless steel A 1 B 1 C 1 A 2 C 2 B 2

Boundary conditions Symmetry planes (flux parallel) Bz z A 1 B 1 C 2 C 1 A 2 Bz At z=+57” and z=-57”, give arbitrary external magnetic field Bz=-1 T@t=1 E-6 s, then Bz ramp to 0 T@t=1 E-4 s and lasts for 40 ms. Note: symmetry BC is an approximation because CYCLIC doesn’t work due to the complexity of this model (i. e. highly unmatched mesh at the low and high edges).

TIME Evaluation point Estimate time constant z 1. Choose the center point at z=0 to read B result. Choosing different point will have different result. Several evaluation points can be chosen to have an average result for time constant. 2. Estimated time constant: 8 ms (40 ms range), 12 ms (~80 ms range), 19 ms (~190 ms range) 3. Eddy current decays faster at the beginning and then more and more slowly after a while. But if the island size becomes small enough, it is still acceptable. Otherwise, it may be a problem. 1. 00 E-06 5. 05 E-05 1. 00 E-04 2. 00 E-02 3. 98 E-02 4. 01 E-02 4. 25 E-02 4. 49 E-02 4. 73 E-02 4. 97 E-02 5. 21 E-02 5. 45 E-02 5. 69 E-02 5. 93 E-02 6. 17 E-02 6. 41 E-02 6. 65 E-02 6. 89 E-02 7. 13 E-02 7. 37 E-02 7. 61 E-02 7. 85 E-02 8. 09 E-02 8. 33 E-02 8. 57 E-02 8. 81 E-02 9. 05 E-02 9. 29 E-02 9. 53 E-02 9. 77 E-02 0. 10008 0. 10248 0. 10488 0. 10727 0. 10967 0. 11207 0. 11447 0. 11687 0. 11927 0. 12167 0. 12407 0. 12647 0. 12887 0. 13126 0. 13366 0. 13606 0. 13846 0. 14086 0. 14326 0. 14566 0. 14806 0. 15046 0. 15286 0. 15526 0. 15765 0. 16005 0. 16245 0. 16485 0. 16725 0. 16965 0. 17205 0. 17445 0. 17685 0. 17925 0. 18165 0. 18404 0. 18644 0. 18884 BSUM_84404 0. 269136 0. 196311 0. 106803 1. 58 E-03 6. 74 E-04 6. 96 E-04 6. 29 E-04 5. 65 E-04 5. 08 E-04 4. 56 E-04 4. 08 E-04 3. 65 E-04 3. 26 E-04 2. 92 E-04 2. 61 E-04 2. 32 E-04 2. 07 E-04 1. 86 E-04 1. 66 E-04 1. 49 E-04 1. 33 E-04 1. 19 E-04 1. 07 E-04 9. 67 E-05 8. 72 E-05 7. 85 E-05 7. 11 E-05 6. 50 E-05 5. 88 E-05 5. 27 E-05 4. 89 E-05 4. 47 E-05 4. 13 E-05 3. 82 E-05 3. 47 E-05 3. 25 E-05 2. 99 E-05 2. 78 E-05 2. 58 E-05 2. 40 E-05 2. 28 E-05 2. 10 E-05 2. 01 E-05 1. 87 E-05 1. 76 E-05 1. 69 E-05 1. 55 E-05 1. 41 E-05 1. 34 E-05 1. 26 E-05 1. 14 E-05 1. 09 E-05 1. 00 E-05 9. 46 E-06 9. 40 E-06 8. 70 E-06 8. 49 E-06 7. 59 E-06 7. 18 E-06 6. 73 E-06 6. 40 E-06 5. 96 E-06 5. 52 E-06 5. 50 E-06 5. 13 E-06 4. 71 E-06 4. 70 E-06 time constant (ms) 4. 73871734 7. 972166998 10. 282 11. 88059914 13. 70875 16. 18444444 18. 644

Eddy current pattern (lower half) y x z B 2 A 2 B 2 cut

Eddy current pattern (upper half) y z x B 2 A 2 cut

Eddy current pattern (lower half) C 1 cut C 1 C 2 y x z

Eddy current pattern (upper half) C 2 cut C 1 C 2 y z x

Eddy current pattern (lower half) A 1 cut y z B 1 x A 1

Eddy current pattern (upper half) B 1 cut y z x