1. HT-7U CASIPP 1 The Engineering Design of the Poloidal Field System of HT-7U Tokamak PF Group of HT-7U Team Chinese Academy of Sciences, Institute of Plasma Physics (CASIPP) P.O.Box 1126, Hefei, Anhui 230031 P.R.C. HT-7U Wu Weiyue, Li Baozeng, Cao Yunluo

2. HT-7U CASIPP 2 1. Main parameters of HT-7U 2. PF coils position & size 3. Conductor design 4. Winding & insulation 5. Analysis on strength of the magnets & structure 6. Fabrication & testing 7. Outlook for the near future

3. HT-7U CASIPP 3 1. Main Parameters of HT-7U Major Radius, R o 1.79 ~ 1.96 m Minor Radius, a0.4 ~ 0.55 m Plasma Current, I P 1 MA Elongation, K x 1.6 ~ 2 Triangularity,  x 0.6 Toroidal Field, B t 3.5 T Plasma Duration~ 1000 s Configuration: Pump limiter Double null Single null Heating and Driving: LHCD3.5 MW ICRH3~3.5 MW ECRH0.5 MW

4. HT-7U CASIPP 4 7095mm 3430mm   7600mm 2500mm H  13300mm

5. HT-7U CASIPP 5 2. PF Coils Position and Size Center of the device Equator plane All PF coils are placed symmetrically about the equator plane

6. HT-7U CASIPP 6  6.65m  6.47m PF Magnets System of HT-7U

7. HT-7U CASIPP 7 Parameters of PF coils No.R(cm)Z(cm)NrNzBw(cm) Bh(cm) 156.4044.10857202.1542.213 256.40454.37257202.1542.213 356.404104.63657202.1542.213 496.447172.051142.1542.213 596.447181.92117122.1542.213 6289.623 149.926101.9742.034 7 324.01983.3 481.9742.034

8. HT-7U CASIPP 8 3. Conductor for PF coils NbTi strands(UNK) with segregated copper is chosen for all PF coils The configuration of the PF CICC Ⅰ (for PF1-5)

9. HT-7U CASIPP 9 The configuration of the PF CICC Ⅱ (for PF6-7)

10. HT-7U CASIPP 10 PF1-PF4 PF5-PF6 Strands conf.(2SC+2Cu)  3  4  (5+1)(1SC+2Cu)  3  4  (5+1) No. of Sc strand12060 No. of Cu strand141 (Φ0.98) 120 (Φ0.98)+ 21 (Φ0.87) Surface Coating with Ni  2  m Pb-Sn-Sb  3  m Peak field  4.5T>2.5T CICC size20.4mm×20.4mm18.6mm×18.6mm Conduit material316LN316LN Conduit thickness1.5mm1.5mm Current (Io)14.5kA14.5kA f(Io/Ic)0.2240.31 Temperature Margin(ΔTs)2.24K1.99K Stable margin(ΔE)350mJ/cm 3 400mJ/cm 3 Parameters about PF CICC

11. HT-7U CASIPP 11 4. Winding and insulation Turns insulation 2 layers kapton 0.06mm, fiberglass 0.44mm; Pancake insulation 0.84mm fiberglass carpet; Ground insulation 5mm fiberglass wrapping; Vacuum pressure impregnates with epoxy resin

12. HT-7U CASIPP 12 PF coil’s winding structure Turns 140 (1 CICC) Inner Radius 55cm Outer Radius71cm Height46cm CICC Length565m (no joint)

13. HT-7U CASIPP 13 7  20=140 turns 2 current terminates 4 cooling tubes Cooling channel L is 130m (28 turns) View of one piece central solenoid coil 0.45m 0.16m  1.1m

14. HT-7U CASIPP 14 6 coils through bolts preloading; Height is 4 m; Total is 6  140=840 turns 4m 5. Analysis on magnets strength and structure

15. HT-7U CASIPP 15 Helium tubes Current terminates Top view of central solenoid  1.87m Helium tubes in a different angle with the current terminates about 45 degree; 6 coils are set in different angle each other also, according to the terminates and helium tubes.

16. HT-7U CASIPP 16 PF coils current waveforms for the basic scenarios Plasma current Ip ignition OH discharge OH charge end

17. HT-7U CASIPP 17 Moment Fr Fz Fr Fz Fr Fz Electromagnetic Force on solenoid are different on each coil and in each moment. Analysis on the structure for the preloading force and Electromagnetic Force on support parts of the assembly solenoid.

18. HT-7U CASIPP 18 6.1mm & 279 MPa 0.3mm & 16 MPa 47.5 MPa The results show the design on strength is suitable and safety enough.

19. HT-7U CASIPP 19 CSMC after winding CSMC with supports A central solenoid model coil (CSMC) had been fabricated in 2000 & tested in 2001. 6. Fabrication and testing for PF system

20. HT-7U CASIPP 20 Parameters of CSMC Inductance 15.4mh Cooling channel 365m I operating 14.5/18KA Peak field5T Stored energy1.62/2.5MJ Parameters of solenoid Turns 9  14=126 Inner radius 37.6cm Outer radius57.3cm Height28.6cm CICC length 368m Inductance 26mh Cooling channel 130m I operating 14.5KA Peak field4.5T Stored energy2.74MJ Turns 7  20=140 Inner radius 55cm Outer radius71cm Height46cm CICC length 565m

21. HT-7U CASIPP 21 CSMC set in testing facility in 2001

22. HT-7U CASIPP 22 Test Facility Parameters D in  3.1 m H in 4.7 m Vacuum 1×10 -5 torr Current leads 2 pairs Imax. 30 kA Refr. 500W/4.5k T opr. 4.5/3.8K

23. HT-7U CASIPP 23 4 days cooling down for CSMC in 1 st testing Part view next

24. HT-7U CASIPP 24 Resistance disappeared in 2 days from 6.5m  Part view next

25. HT-7U CASIPP 25 Resistance from 1m  to 80  in half hour

26. HT-7U CASIPP 26 13 KA in CSMC when 1 st testing in 2001

27. HT-7U CASIPP 27 CSMC just VPI last month in CASIPP

28. HT-7U CASIPP 28 A 600m CICC jacketing line has been set up in CASIPP

29. HT-7U CASIPP 29 Several types CICC have been fabricated More than 8 types CICC with different configuration have been designed and made during past three years. 2 types CICC was made in China(including cabling) 6 types CICC cabling in VNIIKP(Russia) and jacketing in CASIPP

30. HT-7U CASIPP 30 Two pieces 600m CICC has been fabricated in CASIPP this year

31. HT-7U CASIPP 31 7. Outlook for PF system The final design of the PF system will be finished this year. One section of central solenoid coils will be fabricated and tested in the end of this year. All the components(coils, structure and connecting parts) of PF system will be fabricated completely in next year. The assembly central solenoid will be testing with the structure and preloading. The assembly of HT-7U device is planed to start in next year.

32. HT-7U CASIPP 32 HT-7U device will be build in Institute of Plasma Physics, Chinese Academy of Sciences(CASIPP) Sciences Island

33. HT-7U CASIPP 33

34. HT-7U CASIPP 34 Diameter ф0.87mm Critical current (I c )500A(4.5K,5T) 426A(4.5K,5.8T) Number of SC filaments8910 Diameter of SC filament6μm twist10mm Ratio of s. cu1.38:1 Parameters of NbTi Strands (UNK) Polyamide+Vacuum Pressure Impregnates No strands splice No lubricant

35. HT-7U CASIPP 35

36. HT-7U CASIPP 36 Change the insulation bmp with Zhu Ning new-drawing.