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Ex-situ NMR LDRD Progress report 01/27/03. Magnetic and mechanic design Paolo Ferracin. Field calculation for a line current. 2D azimuthal component of the field: Only odd normal (b 3 , b 5, b 7 ,…) and even skew (a 2 , a 4, a 6 ,…) harmonics. y. - I. + I. a. p (r, J). F. x. y.
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Ex-situ NMR LDRDProgress report 01/27/03 Magnetic and mechanic design Paolo Ferracin
Field calculation for a line current • 2D azimuthal component of the field: • Only odd normal (b3, b5, b7,…) and even skew (a2, a4, a6,…) harmonics. y - I + I a p (r, J) F x Paolo Ferracin
y x d t + I - I Line currents in NMR configuration • Distance from the sweet spot: d. • Distance from the y axis: t. • We move the line currents horizontally. • We compute, for a given d and t, the field harmonics. Paolo Ferracin
x d t - I + I Main field y Paolo Ferracin
x d t - I + I Skew quadrupole y Paolo Ferracin
x d t - I + I Normal sextupole y Paolo Ferracin
Comments • Comparison of the curves with Roxie: • line currents: perfect agreement; • blocks ( 20 20 mm) with d 30 mm: very good agreement; • You can cancel either a2 or b3 with 2 horizontal coils (with the same current): • • You can cancel both a2 and b3 with 3 horizontal coils (with the same current): • Paolo Ferracin
2D analysis: HD and RD HD RD • NbTi cables. • Distance d ~ 40 mm, total width 200 mm. • Main field: 2000 3000 Gauss. • Field homogeneity (without full optim.): R = 5 mm 10-3; R = 1.5 mm 10-4 10-5. Paolo Ferracin
2D analysis: SM coils, upper part • Nb3Sn cables. • Distance d ~ 40 mm, total width 200 mm. • Main field: ~ 6000 Gauss. • Field homogeneity: R = 5 mm 10-3; R = 1.5 mm 10-4 10-5. Paolo Ferracin
2D analysis: SM coils • Nb3Sn cables. • Distance d ~ 40 mm, total width 200 mm. • Main field: 2000 3000 Gauss (return current effect). • Field homogeneity: R = 5 mm 10-3; R = 1.5 mm 10-4 10-5. Paolo Ferracin
3D analysis: SM coils • Main field: 2000 3000 Gauss. • Field quality: • strong 3D effect of the ends. • Cube of 3 mm side: • By: 10-4 homogeneity; • Bx and Bz ~ 0.01 By. • Work in progress: • coil geometry optimization; • effect of the iron (2D performed). Paolo Ferracin
3D analysis: SM coils 10-4 10-4 Byy Byx Bz Bx Paolo Ferracin
Mechanical design: Lorentz forces • Fx (internal coil) = - 0.3 MN. • Fx (two external coil) = + 0.5 MN. • Fx in the SM = + 0.6 MN. • Assuming: • shell 20 mm thick (upper limit) and 100 mm long; • shell azimuthal stress at cold: ~ 100 MPa (cool-down) Fx on the coils = ~ 0.4 MN. Paolo Ferracin