Experimental results and Upgrade plan of ECH/CD system in KSTAR

Transcription

1 2015 KSTAR conference, Feb. 27, 2015, Daejeon, Korea Experimental results and Upgrade plan of ECH/CD system in KSTAR J. H. Jeong a, Y. S. Bae a, M. Joung a, J. W. Han a, I. H. Rhee a, I. H. Rhee a, S. W. Jung a, S. W. Yoon a, J. H. Kim a, S. H. Hahn a, M. H. Woo a, W. H. Ko a, S. G. Lee a, K. D. Lee a, H. L. Yang a, J. G. Kwak a, Y. K. Oh a, H. Park a, G. H. Choi b, G. S. Yun b, W. Namkung b, M. H. Cho b, K. Sakamoto c, K. Kajiwara c, Y. Oda c, J. Hosea d, R. Ellis d, H. S. Kim e, Y.-S. Na e, S. H. Lee f, and J. H. Hong f a National Fusion Research Institute, Daejeon, Korea b Department of Physics, POSTECH, Pohang, Korea c Japan Atomic Energy Agency, Naka, Japan d Princeton Plasma Physics Laboratory, Princeton, USA e Seoul National University, Seoul, Korea f Korea Advanced Institute of Science and Technology, Daejeon, Korea jhjeong@nfri.re.kr

2 OUTLINE Introduction Upgrade activities of KSTAR ECH system in 2014 Summary Future plan - 2 -

3 Introduction: Layout of KSTAR ECH system in 2014 Evacuated 31.75mm ID corrugated WG (~40m) 110GHz, loaned from GA (Aug. 2009) 0.3MW/2s (max.) X2 mode at B T =1.4~2.4 T Assisted startup & on-axis heating E-port: 1MW SS (170GHz) N-port: 1MW 15s (110GHz) Evacuated 63.5mm ID corrugated WG (~70m) 170GHz, loaned from JAEA (Jun 2011) 1.0MW/50s (max.) X2 at B T ~3.0 T, X3 at B T ~2.0 T on-axis heating & On/off-axis CD Assisted startup - 3 -

4 Introduction: Mission, requirement and upgrade for 170GHz ECH in 2014 Missions for ECH in 2014 I. On-axis heating to support long-pulse operation KSTAR with high performance II. On/Off-axis CD used for MHD instability control such as ELM period, sawtooth, TM/NTM, toroidal rotation and etc.) And assisted-startup used for reliable startup of KSTAR Requirements Upgrades (Enhancement of performance) I. Long-pulse & high power injection (target parameter was 50sec) Gyrotron conditioning to 1MW/50sec Launcher mirror upgraded for steady-state operation with water-cooled mirrors (successful operation of 0.8MW/41sec) II. RT control of ECH power & target position to change the q profile during a pulse (will be applied for NTM control) Implementation of EC injection timing & mirror position control by PCS - 4 -

5 OUTLINE Introduction Upgrade activities of KSTAR ECH system in Progress of Gyrotron conditioning - Upgrade of ECH launcher mirrors - RT EC injection timing & mirror position control by PCS Summary Future plan successful demonstration of NTM feedback control - 5 -

6 Issue & Progress in conditioning for 170 GHz gyrotron since (1MW/10s/40%) 2012 & 2013 (1MW/20s/40%) 2014 (1MW/50s/40%) Issue Installation & RF generation Action Investigation of operation parameters Alignment of beam & magnet position Issue High power & high efficiency Action Optimized parameter scan 2 nd beam & magnet alignment Issue in 2014 Limitation of pulse duration (due to cathode cooling effect) Action Anode voltage feed-back control Heater voltage control Development of water-cooled mirrors Main mode P j changes (mode conversion) by decrease of I beam dp dt j V I beam( beam I j ) - 6 -

7 Extension of pulse-duration at high-power regime (collaboration with JAEA) I. Anode voltage (V AK ) control at highest power condition # 103: V AK control # 106: No V AK control II. Pre-heating prior to pulse added to extend pulse length (with anode voltage control) # 129: w/o heater control # 139: heater control Power [kw] (@ V DETECTOR ) Mode shift Power [kw] (measured at diode detector) V AK : kv V AK : no control V K : 48.0 kv V BODY : 24.0 kv V AK control V AK control I BEAM I BEAM 25 sec pulse Maximum pulse duration was 30 sec. Additional heater control required!! V HEAT : 25.7 V V HEAT : 28 V/30 sec over heating prior 1 minutes - 7 -

8 1 MW/50 sec operation of 170GHz gyrotron (collaboration with JAEA) RF power: 0.8 MW avg. 53 A V AK control Beam current: not stabilized even for overheating during pulse Vac. Ion curr A max. RF power (calorimetric method) Dummy load (June 03, 2014) 41 A 50 sec long-pulse operation at ~0.94MW (avg. power at the window) achieved by heater boosting (28 V) anode voltage control Total electrical efficiency is about 40 % Maximum collector surface temperature was ~150 degree with I BEAM ~ 50 A Calorimetric power measurement (all of water cooling temperature saturated) Channels ΔT [deg.] Power [kw] Fraction [%] Dummy load % Pre-load % MOU chamber % Collector surface temp. Dc break % Window % V HEATER : 28V over heating during a pulse - 8 -

9 Upgrade of KSTAR ECH launcher (collaboration with PPPL, POSTECH & UNIST) Passively cooled mirrors (used until 2013): - collaboration with PPPL and POSTECH - 1MW for 15seconds, every 15 minutes - 0.8MW/10sec EC beam delivered to KSTAR (limitation of passively cooled mirror) Max. temp. increased to 91ºC for steering mirror [J. W. Han] Laser welding Upgraded with water-cooled mirrors in 2014: - 1MW for CW operation - 1.2MW 170GHz EC beam assumed for thermal analysis (190W/cm 2 Bessel squared heat flux distribution, 30W/cm 2 heat flux from plasma is assumed for steering mirror [R. Ellis, 2014 KSTAR conference]) - Brazing & welding techniques are used for fabrication of mirrors - Rectangular water coolant path enhance the cooling effect Water cooling pipe bellows fixed mirror Shutter Rectangular shape of water coolant path steerable mirror - 9 -

10 Successful operation of water-cooled mirrors for 2014 KSTAR plasma Max. Temp of MOU: ~50 C (ΔT~25 C) ECH: ~41 sec Saturation of ΔT Max. Temp of T/L: ~ 32 C (ΔT~10 C) KSTAR shot sec EC beam delivered to KSTAR to support the highβ & long-pulse operation of KSTAR ΔT of water cooling for mirrors are saturated at 2.6ºC Power loss: 1.40kW (=190W/cm 2) for steering mirror & 1.28kW (=170W/cm 2 ) for fixed Heat flux from the plasma obtained using ΔP of both mirrors and it was ~1.6W/cm 2 Delivered power of 0.8MW is estimated by absorbed power at the fixed mirror (0.16% of absorbed-fraction) Nominal surface temp. of T/L was 32 C (ΔT~10 C). Especially, MOU output port increased to ~50 C Further extension of the pulse width is possible with enhanced water cooling for T/L!! Measurement of surface temperature for T/L by TC sensors Gyrotron MOU TC sensors

11 EC injection & mirror control by PCS (Heating Integrated control system) arbitrary modulation Power control system Change of injection time & modulation period in real time APS controlled by PCS to extract beam current which is the advantage of triode-gun ECE Mirror position scanning in poloidal

12 Demonstration of NTM control [et al., M. H. Woo] shot # Mode amplitude Critical amplitude shot # Critical amplitude Mode amplitude EC power injection MHD control start up Search & suppress Active q tracking Search & suppress algorithm is working correctly Active q tracking algorithm is working correctly Power is injected above the threshold amplitude

13 Summary & future plan Long pulse operation of 170 GHz ECH/CD system in KSTAR Oscillation of 1MW for 50sec was obtained using V AK feed-back and Heater boosting Maximum pulse duration of 41sec EC beam delivered to KSTAR using newly developed water-cooled mirrors Saturation of temperature for gyrotron & launcher-mirror prospects to achieve more than 1MW 100sec. Successfully implemented EC power & mirror control system into the plasma control system

14 Near-term future plan (before 2015 campaign) Target in 2015 (1MW/100sec/40%) Advanced heater boosting scenario to achieve longer pulse operation with stable beam current Temperature monitoring system to measure the surface temperature of T/L will be prepared and water cooling jacket is under consideration Current water-cooled steerable mirror will be upgraded with flexible short-bellows type of mirror from PPPL to avoid hightension force from the water-pipes Current passive-cooled mirror will be replaced with new water-cooled mirror for steady-state operation

15 Repair of water-load I. Water leak at the rotating stem Worn-out of stem due to the friction between the seal and rotating stem 1 MW CW dummy load (loaned from JAEA)Pre-load ECH power Dummy load inside II. TiO2 coating melted away on the surface of dummy load

16 Upgrade plan of KSTAR ECH system EC Power GHz, 1MW, 50s 170GHz, 1MW, 100s 105/140GHz, 1MW Launcher 1MW 2set 1MW 2set & Design of two beam launcher (2MW) Speed Motor design 10 degree/sec 170GHz, 1MW 105/140GHz, 2MW 1MW 2set & 2MW 1set (Fabrication of two beam launcher) 170GHz, 1MW (will be return to JAEA) 105/140GHz, 3MW 1MW 2set & 2MW 1set Fast moving system > 50 degree/sec > 50 degree/sec > 50 degree/sec Power cap. Steady-state Steady-state Steady-state Steady-state

17 New 3 MW ECH upgrade plan [et al., Y. S. Bae] E port 1MW SS (170GHz) + New 2-beam, 2 MW SS (105/140GHz) Evacuated mm ID corrugated waveguide (~40 m) Evacuated 63.5 mm ID corrugated waveguide (~70 m) 110GHz/300kW(2s) N port 1MW SS (105/140GHz) Dash lines: New waveguides (63.5 mm ID) New 3 gyrotrons (1MW, 300 s, 105/140 GHz dual freq.) 170GHz/1MW(50s) Room for HV PS 105/140 GHz dual frequency for new ECH system 105 GHz for 1.8 ~ 2.2 T 140 GHz for 2.5 ~ 2.7 T (together with 170 GHz) 105/140GHz dual freq. gyrotron

18 Thank you for your attention! National Fusion Research Institute realizes Green Korea getting joined with human beings, environment and technology

19 EC injection & mirror control by PCS Mirror control system Mirror response time: ~20ms Power control system Change of injection time & modulation period in real time APS controlled by PCS to extract beam current which is the advantage of triode-gun Enhancement of mirror spee by updates of motor driver arbitrary modulation ECE Mirror position scanning in poloidal

20 Plasma experiments using KSTAR ECH system I. Ar transport experiments with ECH [et al., J. H. Hong] Different transport behavior of core plasma according to ECH deposit positions Feasibility of impurity control using ECH? II. Toroidal Rotation Profile Structure in L- and H-mode KSTAR Plasmas [et al., Y. J. Shi] Rotation Profiles for ECH+NBI plasmas No ECH VUV Ar 15+ ECH Non ECH ECH On-axis ECH r/a = SXR emissivity On-axis ECH was most effective to suppress the core accumulation!! H-mode:on-axis ECH make lager Vφ, Clear pivot point inside pedestal L-mode:off-axis ECH make larger Vφ No pivot point in rotation profile ITG TEM transition occurs inner region for on axis ECH outer region for off axis ECH

21 Upgrade plan of ECH launcher system in 2015 Design features of water-cooled steerable mirror with 3-D printing (collaboration with PPPL & UNIST) Enables coolant to be passed through steering fork & tube Flexible short-bellows transfer water from mirror to fork Only one-angular motion per bellows & to reduce high-tension force The fork will be 3-D printed with coolant channels inside Implementation of fast actuator system to apply NTM stabilization (in 2016) Poloidal steering actuator will upgraded with fast motor & encoder [Conceptual design of generation of 2.0 steerable mirror assembly, R. Ellis]