AWB NSTX TF Flag Joint Design Review April 10, 2003 Art Brooks

AWB 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 )

AWB ProE Model of TF Flag Geometry Epoxy layer (not present in latest design) Contact region Inner Leg Outer Turn

AWB Geometry Imported to ANSYS and Meshed Higher order tetra elements used to auto-mesh irregular geometry 71/2 KA Current

AWB Contact Region Modeled as finite thickness with equivalent resistivity

AWB KA Waveform Driving Thermal Model Analysis assumes the Full I2t (6.5e9 a2s) based on.7 sec FT and L/R decay.

AWB End Of Flat-Top Temperature Distribution assuming 6  in 2 Note: 6  in 2 Contact Resistance requires ~1.4 ksi contact pressure (Copper-on-Copper)

AWB End Of Flat-Top Temperature Distribution

AWB End of Pulse Temperature Distribution assuming 6  in 2

AWB Temperature Peaks shortly after EOFT 176 C Flat top would have to be shortened to ~0.26 s to limit max temperature to 120 C at 6  -in2

AWB Note: 4 micro-ohm-in2 Contact Resistance requires ~2.0 ksi contact pressure (Copper-on-Copper) End Of Flat-Top Temperature Distribution assuming 4  in 2

AWB End Of Pulse Temperature Distribution

AWB Flat top would have to be shortened to ~0.41 s to limit max temperature to 120 C at 4  -in2 Again, Temperature Peaks shortly after EOFT

AWB End Of Flat-Top Temperature Distribution assuming 1  in 2 Note: 1  in 2 Contact Resistance expected with Silver Plated Joint and minimum 1 ksi press

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AWB End Of Pulse Temperature Distribution assuming 1  in 2

AWB Temperature Peaks shortly after EOFT Flat top of 0.7 s achievable Max temperature less than 120 C at 1  -in2

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AWB 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

AWB 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

AWB SPARK Model of NSTX TF Coil Geometry Only With Current Flow

AWB t=.01 s t=. 1 s Current Penetration very quick Current penetrates from both sides of Lower Flag due to field from Upper Flag Current nearly resistively distributed

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AWB 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

AWB Note: Jump in loads at ends results from change in FEA mesh density

AWB D distribution of IL Outer Turn Flag Forces

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