Inner PF Coil Design Updated C Neumeyer 2/2/10

Changes Since Prior Version Added electrical insulation – Account for 3-wire system ground fault – Account for CHI voltage (PF1a, PF1b only) Re-optimized conductor size and turns in PF1b and PF1c – Necessary to use unique conductor cross sections in all three coils (PF1a, PF1b, PF1c) Preserving conductor similarity in PF1b and PF1c resulted in too much performance reduction in PF1c (already underperforming on ESW basis)

Design Considerations Constraints – Amp-turns per J. Menard – Fit in existing R, Z, dR, dZ per J. Chrz – Use same conductor size in PF1b and PF1c Design variables – PS voltage (1kV or 2kV) – Turn and ground insulation thickness – Number of layers and turns – Cooling hole diameter Design objectives – Favoring increase in #turns rms ripple current < 1% of peak current w/o external filter inductor Transrex current < 24kA and to be minimized – Favoring decrease in #turns Packing factor and ESW capability dI/dt in PF1b and PF1c > 35kA-turn/mS for CHI Forcing factors (V-I*R)/L > existing PF1a and PF1b Voltage induced from OH < 50% of PS voltage Worst case induced voltage ~ Transrex Vdc =1012V << Transrex Vdc_MOV*4 ~ 2.4kV Cooldown time <= 1200s with 400psi pressure drop No change since prior version

Methodology NSTX_CSU_Design Spreadsheet – Input geometry, turns, insulation, etc. – Calculate flow/pressure drop, ESW, self-inductance, ripple current, Idot, etc. Mutual inductance matrix – Calculate mutual inductance matrix using ICC – Estimate max induced voltage assuming I_dot = V/L in each circuit independently Calculate sum of M*I_dot as if each coil open circuited while others at max I_dot Use XL solver to find turns adjuatment ratio in PF1a/b/c to minimize largest induced voltage – Constrain turns such that Transrex PS current < 24kA – Recalculate M matrix using ICC – Determine voltage induced from OH = M*Ioh_dot Worst case induced voltage – Run LRSIM with all circuit at Vmax except one open at a time Cooldown time – Run KCOOL Evaluate results and iterate No change since prior version

Summary of New Design ParameterUnitsExisting PF1APF1APF1BPF1C Total CurrentkA-turn ESWSec nR*nZ=nTurns2*10=204*16=642*16=322*10=20 Current per turnkA Max ripple 1 % Min Forcing factor 2 p.u Max slew rate 3 kA-turn/mS Max OH induced voltageVolt Worst case induced voltageVolt Voltage safety factor turn, ground na29,3552,5130,5230,39 Cooldown timeSec – max ripple (amp rms/rated current) occurs in 1kV, 6-pulse configuration 2 – min forcing factor ocurrs in 1kV configuration 3 – max slew rate based on 2kV configuration

Conductors Was not able to use common conductor for PF1b and PF1c

Power Supplies PF1a  Y + -  Y  Y  Y PF1b (upgrade 1) +8kA PF1c (upgrade 1) +13kA PF1b (upgrade 2) +/-8kA or +8kA PF1c (upgrade 2) +/-18kA or +18kA

Summary Inner PF coil designs revised Meet req’ts except – ESW < 5.5s on PF1a & PF1c Upgrade path exists based on Transrex PS Ready for design point revision – Need influence matrix update (R Hatcher) – Need equilibria update (J Menard) – Will post on web as open revision