1. Overview of the KSTAR commissioning M. Kwon 3 June, 2008

2. 1. To test the components and systems after system integration. 2. To demonstrate that systems are in accordance with the design values and the performance criteria. 3. To identify any defect preventing the device operation and plasma experiments. Commissioning Objective

3. 1. Vacuum quality in every environment, before & after cool-down. 2. Controlled cryogenic cool-down of all superconducting magnet system. 3. Status of the SC magnet assembly without individual cool-down test. 4. Performance of the Nb 3 Sn magnet system during the 1 st plasma discharge. Checkpoints during the Commissioning

4. Commissioning Milestones 1 st Plasma June 30 Cooled-down May 02

5. Vacuum pumping system operation VV baking operation Discharge cleaning Gas fuelling system operation Base pressure of VV Target : 5 x 10 -7 mbar, achieved < 3 x 10 -8 mbar Base pressure of cryostat at room temperature Target : 1 x 10 -4 mbar, achieved < 1 x 10 -5 mbar VV baking : 100 0 C DC glow discharge cleaning(H2, He) Fueling system operation & testing  Major Operation  Operation Results Vacuum commissioning Gas : He No. of Electrodes : 1 RF Power : 200 W DC Bias Voltage : 400 V DC Current : 4 A Operation Pressure : 6.0  10 -3 mbar

6. Vacuum vessel pressure (Mar. 08)

7. Cryostat pressure (Mar. 08)

8. Operation & control of the helium refrigeration system & helium distribution system (9 kW @ 4.5 K). Controlled cool-down of cold systems: SC magnet, structures, busline, thermal shields, current leads. Superconducting phase transition  Major Operation  Control & Monitoring Hydraulic parameters Temperature, pressure & flow distribution Mechanical monitoring Stress & displacement Superconductor monitoring Coil resistance & SC phase transition Safety Vacuum & helium pressure monitoring Cool-down commissioning

9. TF coilCS coilPF Coil conductorNb3Sn & Incoloy 908 Nb3Sn & Incoloy 908 (PF5) NbTi & 316 LN (PF6,7) No. of coil164 pair3 pair Total length10.2 km3.8 km11.2 km Cooling channel of each coil4 CS1 : 10, CS2 : 8 CS3 : 4, CS4 : 6 PF5 : 8 PF6 : 8, PF7 : 6 Length of each channel160 m67 m PF5 : 176 m PF6 : 315 m, PF7 : 285 m Cold mass170 ton60 ton70 ton Operating temperature5 K Coolant 4.5 K SHe P > 5.5 bar Mass flow rate > 300 g/s 4.5 K SHe P > 5.5 bar Mass flow rate ~150 g/s 4.5 K SHe P > 5.5 bar Mass flow rate ~ 150 g/s CS1U CS2U CS3U CS4U CS1L CS2L CS3L CS4L KSTAR SC coils

10. Cool-down of KSTAR In April 26, KSTAR superconducting coils were successfully cooled-down.

11. Controlled cool-down (∆T < 50 K) The maximum temperature difference in the magnet structures was carefully controlled within 50 K during the cool-down.

12. Mass flow rate The gaseous helium of maximum 200 g/s was supplied by the clod box. After cool-down, the SC coils were cooled by the 600 g/s supercritical helium of cryogenic circulator to its operating temperature.

13. Temperature distribution in the thermal shields The cryostat thermal shields were well cooled below 70 K. The maximum temperature of the CRTS measured in 180 K on the blank cover plate without cooling lines. The temperature of the vacuum vessel shield was distributed in 90 K ~ 120 K

14. Cryostat vacuum during cool-down After cool-down, the vacuum pressure of the cryostat reached to 2.6E-8 mbar. The partial pressure of each gas greatly decreased as coil cooling and the residual helium gas was kept almost constant pressure level.

15. SC transition measurement The superconducting phase transition of the SC coils was clearly observed during the 1 st cool-down. The SC transition of Nb3Sn and NbTi coils appeared at 18K and 9K, respectively. KSTAR Coils SC strand Tc [K] Expected Measured [K] [K} TFNb3Sn18.317.9 PF1 PF1UNb3Sn 18.318.2 PF1LNb3Sn PF2 PF2UNb3Sn 18.318 PF2LNb3Sn PF3 PF3UNb3Sn18.318 PF3LNb3Sn18.318 PF4 PF4UNb3Sn18.317.9 PF4LNb3Sn18.318 PF5 PF5UNb3Sn18.318 PF5LNb3Sn18.318 PF6 PF6UNbTi9.210 PF6LNbTi9.29.8 PF7 PF7UNbTi9.210 PF7LNbTi9.210 The measured Tc of the 16 TF coils SC transition measurement [The results of the measured Tc of SC coils]

16. Joint Resistance The voltage drops were measured at each SC bus-line, which consists of several numbers of electrical joints. The joint resistances were estimated by linear fitting to the measured V-I curves. All of the KSTAR lap joint resistances satisfied the design value of 5 nΩ. Coil Lap Joints [EA] Total R [nΩ] Average [nΩ /joint] Design Value TF811.11.38 < 5 nΩ PF1715.62.23 PF2711.11.59 PF31220.31.69 PF41217.41.45 PF51225.22.1 PF61211.20.93 PF784.110.51 [The KSTAR lap joint of the SC bus-line]

17. TR No. Radial displacements (mm), @ 11K Sensor indication (Reset at 311 K) Contraction from 293 K FEM analysis Deviation TR 01-8.59 - 7.93 -8.2-0.27 TR 02-8.26-7.67-8.2-0.53 TR 03-8.33 -7.66 -8.2-0.54 TR 04-8.26-7.71-8.2-0.49 Radial displacements of the toroidal ring Reference ; “KSTAR Magnet Structure Stress Analysis”, Efremove, July, 2003 Radial displacements of the toroidal ring from 293 K to 11 K were measured in the range of 7.66 mm ~ 7.93 mm, which is comparable of the FEM analysis result. The maximum deviation of the segments is just 0.006 % as compared with the diameter of the ring, 5780 mm.

18. Superconducting joint resistance measurement Insulation test at cryogenic temperature Magnet power supply control TF coil charge & discharge : up to 15 kA (B0 = 1.5 T, Bm = 3.1 T) PF coil charge & blip operation  Major Operation  Control & Monitoring Coil current & voltage Field on SC magnet, in vacuum vessel Coil performance under the dc & pulse field variation Interlock & safe discharge (quench discharge) SC Magnet Commissioning

19. TF magnet SD & FD test SD & FD test at 5 kA QD & MD adjust

20. TF coil charging test (15 kA, 8 hr)

21. PF Blip Operation PF1 : 2.7 kA PF2 : 2.1 kA PF3 : 2.8 kA PF5 : 2.1 kA PF6 : 2.3 kA PF4 : 2.6 kA PF7 : -2.3 kA

22. PF1 coil blip test

23. TF & PF1 coil charging test

24. ICRF Discharge test

25. Cathode voltage (yellow) Body voltage (green) Beam current (pink) Body current (blue) RF power: ~ 400 kW, 100 ms pulse Beam current Forward RF signal Backward RF signal Forward RF signal (at the end of transmission line) Gyrotron operation parameters (80 kV, 18 A, 100 ms) 84 GHz, 500kW CPI Gyrotron (2008. 4. 21)  Gyrotron installation: 2008. 4. 21  Gyrotron Aging: 2008. 4. 28 –  400 kW, 100 ms RF aging  Transmission line is under aging Status of KSTAR ECH commissioning

26. Fueling & wall conditioning Heating system readiness test MPS and BRIS tuning ECH pre-ionization Plasma start-up and optimization  Major Test  Control & Monitoring Coil performance under the dc & pulse field variation Measurement of plasma parameters (current, density, image, loop voltage, H-alpha etc.) Change of ECH parameters Plasma control and monitoring Plasma Start-up Commissioning

27. KSTAR SHOT number 586 (2008. 05. 30) ECH Power (A.U) PF Current (A) Line Density (10 19 m -2 ) H- α Intensity (A.U) Loop Voltage (V) Total Current (A) Time (sec)

28. KSTAR will be one of the most effective devices for ITER relevant operation and physics for reliable fusion reactor.  Accumulation of the technical know-how for the superconducting tokamak operation  Leading the high performance steady-state plasma experiment Goal Phase First plasma SC tokamak operation technology (Bt = 3.5 T) D-shaped plasma (Ip >1 MA, D 2 ) H -mode achievement Collaboration for operation First plasma SC tokamak operation technology (Bt = 3.5 T) D-shaped plasma (Ip >1 MA, D 2 ) H -mode achievement Collaboration for operation Long pulse operation (t pulse > 100 s) AT operation Tech. (P heat < 20 MW) ITER pilot device operation Collaboration for steady- state operation Long pulse operation (t pulse > 100 s) AT operation Tech. (P heat < 20 MW) ITER pilot device operation Collaboration for steady- state operation Long pulse operation (t pulse > 300 s) Stable AT operation (P heat > 20 MW) ITER satellite operation Collaboration for advanced research Long pulse operation (t pulse > 300 s) Stable AT operation (P heat > 20 MW) ITER satellite operation Collaboration for advanced research High beta AT mode & long pulse Reactor material test (divertor, blanket) High beta AT mode & long pulse Reactor material test (divertor, blanket) SC Tokamak Operation Technology Steady-state Operation High-beta, AT Operation Steady-state AT Activities 1 st PlasmaD-D Reaction100 s1MAIon Temp > 10 keV Year PHASE 1PHASE 2PHASE 3PHASE 4 08091011121314151617181920212223242507 ITER Construction StartITER 1 st Plasma Milestone Long-term operation plan

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