First st field ld qualit lity y measurem suremen ents ts of a - PowerPoint PPT Presentation

Click to edit Master title style FERMILAB-SLIDES-19-056-TD First st field ld qualit lity y measurem suremen ents ts of a 15 T Nb3Sn n Dipole ole Demo monst nstrat rator or September 24, 2019 Thomas omas Straus uss, E. Barzi, J. DiMarco, V.V. Kashikhin, I. Novitski, M. Tartaglia, G. Velev, A.V. Zlobin US Magnet Development Program This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics. 1 Tue-Mo-Or7-02

Click to edit Master title style Outline • Data collection • Magnetic Measurement System • Measurement sensitivity Centering Corrections • Measurement discussion • • Transfer Function (magnitude of the field) • Loop (Dynamic effects, eddy current) • Z-scan (behavior along magnet length) • Harmonics from Stair Step (geometric harmonics) Comparison with Simulation • • Decay and Snapback • Summary 2

Click to edit Master title style Magnetic Measurement System • Rotating Coil Measurement System at Fermilab Vertical Magnet Test Facility – 0.75 – 1 Hz rotation R ref set to 17 mm (56% of aperture) – Shaft with attached probe to scan ‘warm bore’ of the magnet, 3 m stroke • • Two probes, offset by 130 mm (16 layers, 2 Loops, 13 Windings each) – 130 mm x 22.25 mm PCB probe – 26 mm x 22.25 mm PCB probe – Dipole bucked signal 3

Click to edit Master title style 26 mm Probe sensitivity 130 mm probe sensitivity similar Probe sensitivity b n vs n (26 mm probe) Probe sensitivity a n vs n (26mm probe) 100 100 Ignore Allowed terms 10 10 b n in units a n in units 1 1 0.1 0.1 ~ 0.1 units ~ 0.1 units 0.01 0.01 0 2 4 6 8 10 0 2 4 6 8 10 harmonic order harmonic order Sensitive to ~ n=7 1500 A Stair step 2000 A Stair Step 4000 A Stair Step 1500 A Stair step 2000 A Stair Step 4000 A Stair Step 6000 A Stair Step 8000 A Stair Step 9000 A Stair Step 6000 A Stair Step 8000 A Stair Step 9000 A Stair Step 𝒐−𝟐 ∞ 𝒚 + 𝒋𝒛 𝑪 𝒛 + 𝒋𝑪 𝒚 = 𝑪 𝟐 𝟐𝟏 −𝟓 ෍ 4 ሺ𝒄 𝒐 + 𝒋𝒃 𝒐 ) 𝑺 𝒔𝒇𝒈 𝒐=𝟐

Click to edit Master title style Centering Correction Higher order units versus current Hysteresis feed-down from b 3 0.5 10 0.4 0.3 0 0.2 0.1 Data indicates probe is b n , a n in units b n , a n in units -10 well centered for this 0 position -0.1 -20 -0.2 b8 stair step (26 mm probe) -0.3 b9 stair step (26 mm probe) -30 a8 stair step (26 mm probe) -0.4 a9 stair step (26 mm probe) b2 stair step (26 mm probe) b8 loop (26 mm probe) a2 stair step (26 mm probe) b9 loop (26 mm probe) -0.5 b2 loop (26 mm probe) -40 3000 4000 5000 6000 7000 8000 9000 10000 0 2000 4000 6000 8000 10000 Current [A] Current [A] 5

Click to edit Master title style Transfer Function for multiple measurements 2.2 2.1 All MDPCT1 measurements overlaid 2 1.9 Iron Saturation above 2.5T TF [T/kA] 1.8 1.7 1.6 1.5 Stair step 26 mm Loop 20 A/s (26 mm probe) Loop 20A/s (130 mm probe) Loop 40 A/s (26 mm probe) Loop 40 A/s (130 mm probe) Loop 80 A/s (26 mm probe) Loop 80 A/s (130 mm probe) Acc Cycle (26 mm probe) 1.4 0 1000 2000 3000 4000 5000 6000 7000 8000 9000 Current [A] 6

Click to edit Master title style Loop measurements Conductor uses 11 mm width stainless core (nearly full width of cable) TF vs current for varying ramp rates 1.95 1.9 Pre-cycle and ramp to 9 kA 1.85 1.8 TF [T/kA] 1.75 1.7 1.65 1.6 1.55 Near identical shape at high fields, very small 1.5 variation in the magnetization at low 1.45 0 2000 4000 6000 8000 Current [A] Loop 20 A/s (26 mm probe) Loop 40 A/s (26 mm probe) Loop 80 A/s (26 mm probe) 7

Click to edit Master title style Loop harmonic b3 vs current for various ramp rates 200 Near identical, no large eddy current or coupling between strands likely due to core. 150 Large persistent current/hysteresis effect. 100 b 3 in units 50 0 -50 -100 0 2000 4000 6000 8000 Current [A] Loop 20 A/s (26 mm probe) Loop 40 A/s (26 mm probe) Loop 80 A/s (26 mm probe) 8

Click to edit Master title style 20 A/s Loop measurements normal harmonics b 3 , b 5 , b 7 and b 9 vs current for Loop measurements 50 b 3 ‘drift’ is due to iron saturation (see previous talk, wait for comparison with calculation later) 30 b n in units 10 -10 -30 -50 0 2000 4000 6000 8000 Current [A] b3 Loop 20 A/s (26 mm probe) b5 Loop 20 A/s (26 mm probe) b7 Loop 20 A/s (26 mm probe) b9 Loop 20 A/s (26 mm probe) 9

Click to edit Master title style 20 A/s Loop measurement skewed harmonics a 3 , a 5 , a 7 and a 9 vs current for Loop measurements 4 a 3 offset points to small misalignment between coils, 2 hysteresis origin could be from b 3 contribution 0 a n in units -2 -4 -6 -8 -10 0 2000 4000 6000 8000 Current [A] a3 Loop 20 A/s (26 mm probe) a5 Loop 20 A/s (26 mm probe) a7 Loop 20 A/s (26 mm probe) a9 Loop 20 A/s (26 mm probe) 10

Click to edit Master title style Z scan TF along magnet bore Measured at 9kA 1.6 Return end Lead end 1.4 1.2 1 TF [T/kA] 0.8 0.6 0.4 0.2 0 -0.5 -0.3 -0.1 0.1 0.3 0.5 z position around magnet center [m] z scan 26 mm probe (26 mm step) z scan, 130 mm probe (130 mm step) z scan 26 mm probe (130 mm step) 11

Click to edit Master title style Z scan TF, zoom Variations due to end field contributions Measured at 9kA z scan TF along center axis 1.476 Lead end Return end 1.474 1.472 1.47 TF [T/kA] 1.468 1.466 1.464 1.462 1.46 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 z position around magnet center [m] z scan 26 mm probe (26 mm step) z scan 130 mm probe (130 mm step) 12

Click to edit Master title style Z scan harmonics Measured at 9kA, 26 mm probe b3 in center is consistent with loop • 20 and stair case measurements 15 Return end • Oscillatory pattern likely due to Lead end cable transposition pitch (~12 cm) 10 5 b n in units 0 -5 -10 -15 -20 -25 b2 b3 b5 -30 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 z position around magnet center [m] Errors smaller than symbols 13

Click to edit Master title style Z scan harmonics • a3 depends on z-axis (possible Measured at 9kA misalignment), and value in center is 15 consistent with loop and stair case measurements Lead end 10 Return end • Oscillatory pattern likely due to cable transposition pitch (~12 cm) 5 a n in units 0 -5 -10 a2 a3 a5 -15 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 z position around magnet center [m] Errors smaller than symbols 14

Click to edit Master title style Geometrical Harmonics Geometric harmonics nearly identical in stair step and loop, small except for a2,a3,b2, and b3 • Stair step, 26 mm probe current B main TF b2 b3 b4 b5 b6 b7 b8 b9 a2 a3 a4 a5 a6 a7 a8 a9 7003 10.599 1.514 1.4 -7.4 -0.9 0.1 -0.1 1.3 0.1 0.1 -1.3 -3.4 0.6 0.1 0.1 0.0 0.0 0.0 • Loop, 20 A/s, both probes, 130 mm offset in between Loop 20 A/s 26 mm 6996 1.512 1.4 -7.6 -1.0 0.2 -0.2 1.4 0.1 -0.2 -1.4 -3.7 0.8 0.2 0.2 0.1 0.0 0.0 Loop 20 A/s 130 mm 6996.030 1.514 -1.2 -7.2 -1.8 -1.3 -0.1 0.7 0.2 0.0 -1.5 -3.0 2.4 1.2 0.1 0.1 -0.1 0.0 15 Harmonics averaged harmonics in units b2 b3 a2 a3 10 from up and down ramp 5 0 -5 -10 -15 0 2000 4000 6000 8000 10000 Current [A] 15

Click to edit Master title style Transfer Function Deuterium probe was loaned to FNAL by GMW MDPCT1 TF vs current Stair Step (26 mm probe) Rubber NMR (2.5-5.5T) 1.90 Large magnetization at Comsol 3D low currents 1.80 Deuterium NMR (8-22T) ROXIE 2D TF [T/kA] 1.70 1.60 1.50 Vadim Kashikhin: 2% difference between the 2D Roxie and 3D COMSOL transfer functions at high field due to boundary condition in 2D setup while 3D is ok. 1.40 0 2,000 4,000 6,000 8,000 10,000 Current [A] 16

Click to edit Master title style b 3 versus dipole field 100 Plotting against the main field resolve 2D simulation offset for fair comparison 50 b 3 in units 0 Persistent current is large, as expected -50 b3 Roxie 2D b3 Stair Step (26 mm probe) -100 b3 20 A/s Loop (26 mm probe) b3 20 A/s Loop (130 mm probe) -150 0 2 4 6 8 10 12 14 B 1 in [T] 17

Click to edit Master title style b 5 versus dipole field 25 b5 Roxie 2D 20 b5 Stair Step (26 mm probe) 15 b5 20 A/s Loop (26 mm probe) b 5 in units 10 b5 20 A/s Loop (130 mm probe) 5 0 -5 0 2 4 6 8 10 12 14 B 1 in [T] 18

Click to edit Master title style Decay and Snapback 100 A reset current 760 A plateau for 15 min b 3 versus time 10 A/s 0 1000 -5 800 -10 Current [A] b 3 in units 600 -15 -20 400 -25 200 -30 -35 0 700 800 900 1000 1100 1200 1300 1400 time [s] B3 Current 19

Click to edit Master title style Snapback 100 A reset current 760 A plateau for 15 min b 3 versus time 10 A/s -25 1200 -27 1100 Current [A] b 3 in units -29 1000 -31 900 -33 800 -35 700 1300 1320 1340 1360 1380 1400 time [s] B3 Current 20