AWB 041003 1

NSTX TF Flag Joint Design Review

April 10, 2003

Art Brooks

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Overview of TF Flag Analyses

• Thermal/Electrical Response ( ANSYS )– Impact of Assumed Contact Resistance on Joint

temperature and pulse length

• Inductive Effects ( SPARK )

• Force Distribution ( SPARK )

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ProE Model of TF Flag Geometry

Epoxy layer(not present in latestdesign)

Contact region

Inner LegOuter Turn

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Geometry Imported to ANSYS and Meshed

Higher order tetra elementsused to auto-mesh irregular geometry

71/2 KA Current

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Contact Region Modeledas finite thickness withequivalent resistivity

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71 KA Waveform Driving Thermal Model

0

10000

20000

30000

40000

50000

60000

70000

80000

-1 -0.5 0 0.5 1 1.5 2 2.5

Full I2T L/R

108712

Analytic

Analysis assumes the Full I2t (6.5e9 a2s) based on .7 sec FT and L/R decay.

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End Of Flat-Top Temperature Distribution

assuming 6 in2

Note:

6 in2

Contact Resistancerequires ~1.4 ksicontact pressure(Copper-on-Copper)

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End Of Flat-Top

Temperature Distribution

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End of Pulse Temperature Distribution assuming 6 in2

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Temperature Peaks shortly after EOFT

176 C

Flat top would have to be shortened to ~0.26 s to limitmax temperature to 120 Cat 6 -in2

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Note:4 micro-ohm-in2Contact Resistancerequires ~2.0 ksicontact pressure(Copper-on-Copper)

End Of Flat-Top Temperature Distributionassuming 4 in2

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End Of Pulse

Temperature Distribution

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Flat top would have to be shortened to ~0.41 s to limitmax temperature to 120 Cat 4 -in2

Again, Temperature Peaks shortly after EOFT

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End Of Flat-Top Temperature Distributionassuming 1 in2

Note:

1 in2

Contact Resistanceexpected with Silver Plated Joint and minimum 1 ksi press

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End Of Pulse Temperature Distributionassuming 1 in2

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Temperature Peaks shortly after EOFT

Flat top of 0.7 s achievableMax temperature less than 120 Cat 1 -in2

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Flat Top Time to Limit Max Temperature at Joint to 120 C

71 KA Waveform, L/R Decay

0.0

0.2

0.4

0.6

0.8

1.0

0 2 4 6 8Contact Resistance, -in2

Fla

t top

, sec

120 C Limit at Joint

~80 C Limit in Turn

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Thermal Response Summary

• Peak Temperature at Joint occurs near threaded inserts, but localized

• Peak Temperature very dependent on Assumed contact resistance– Higher than expected contact resistance will force

shortening of flat top at 6 kG– Full I2t achievable at 1 -in2

• Bulk Heating of Flag small.• Bulk Temperature not significantly impacted by

assumption of contact resistance

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Inductive Effects

• ANSYS analyses of Joint Heating assumed currents were resistively distributed

• SPARK Model used to assess current penetration• Time constants for current penetration shown to

be small

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SPARK Model of NSTX TF Coil

Geometry Only With Current Flow

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t=.01 s t=. 1 s

Current Penetration very quick

Current penetrates from both sidesof Lower Flag due to field from Upper Flag

Current nearly resistively distributed

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Current Fraction In Upper Half of Upper TF Flags

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0 0.5 1

Time, sec

Fra

ctio

n i

n U

pp

er H

alf

Inner Leg Inner Turn

Inner Leg Outer Turn

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EM Force Distribution In Flags

• Spark Model Also Used to Determine EM force distribution in Flag from TF Field– Out of Plane forces from PF not repeated at this time.

• Forces Calculated for split flag configuration• Resultant forces predominately vertical with 1/R

distribution• Forces not recalculated for solid flag, but

– Vertical forces should still have same 1/R behavior and magnitude

– Radial forces should be larger in flag and should work to keep joint closed

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Force Distribution on TF Flags

0

100

200

300

400

500

600

700

800

900

1000

0.00 5.00 10.00 15.00

Distance from Contact Joint, in

Ru

nn

ing

Lo

ad

, l

bs

/in

Upper Flag, Upper Half

Upper Flag, Lower Half

Lower Flag, Upper Half

Lower Flag, Lower Half

1/R fit LL

1/R Fit LU

1/R Fit UL

1/R Fit UU

Note: Jump in loadsat ends results fromchange in FEA mesh density

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2 D distribution of IL Outer TurnFlag Forces

Radius, in 0.00 1 1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 6.00 6.50 7.00 7.50 8.00 8.50 9.00 9.50 10.0 10.5 11.0

Lower Flag 63 67 64 60 55 51 46 43 39 36 33 31 29 27 25 24 22 21 20 18 17 17 33 Upper Half 136 146 137 129 120 110 102 94 87 81 76 71 66 62 59 56 53 50 47 45 43 41 83(Forces in Newtons) 159 172 160 149 138 127 118 110 103 96 90 85 81 76 73 69 66 63 60 58 56 54 111

184 200 181 165 151 138 128 120 112 105 99 94 89 85 81 77 74 71 68 65 63 61 128215 236 204 180 162 148 137 128 120 113 107 102 97 92 88 85 81 78 75 72 69 66 142132 133 106 90 81 74 68 64 60 57 54 52 49 47 45 43 42 40 39 37 35 33 89

Running Load, lbs/in 400 429 383 347 317 291 270 251 234 220 207 195 185 175 167 159 152 145 139 133 127 122 2631/R Fit 484.013 429 384 349 319 294 272 254 238 223 211 200 189 180 172 164 158 151 145 140 135 130 126

Lower Flag 108 119 125 124 118 110 102 95 88 82 77 72 68 64 61 58 55 53 50 48 47 47 99 Lower Half 233 265 261 255 241 226 210 196 183 171 161 151 143 135 129 122 117 112 107 103 100 96 182(Forces in Newtons) 284 318 299 282 263 245 227 212 198 186 176 166 157 149 142 136 130 125 120 115 111 106 203

347 387 347 313 285 261 242 225 211 198 187 178 169 161 154 147 141 135 130 125 120 115 223419 480 406 349 309 281 259 242 227 215 204 194 185 177 170 164 157 152 146 141 135 130 255285 286 223 184 162 147 136 128 121 115 109 105 100 96 93 90 87 84 81 78 75 72 144

Running Load, lbs/in 754 834 747 677 620 570 529 494 462 435 411 389 369 352 337 322 309 296 285 275 265 255 4971/R Fit 942.386 834 748 679 621 572 530 494 463 435 411 389 369 351 335 320 307 294 283 272 262 253 245

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Summary

• Thermal distributions and EM loading provided as input to Structural Analysis being performed and presented by Irv Zatz