Operational progress of 1MW ECH system in KSTAR Meeting... · 8th IAEA TN on SSO for magnetic fusion devices (May. 29, 2015, NARA, Japan) -3- Introduce: Layout of KSTAR ECH system

Operational progress of 170GHz‐1MW ECH system in KSTAR

J. H. Jeonga, Y. S. Baea, M. Jounga, M. H. Wooa, S. H. Hahna, H. Hana, S. W. Junga, J. W. Hana,I. H. Rheea, H. L. Yanga, J. G. Kwaka, Y. K. Oha, H. Parka, M. Kwona,

K. Sakamotob, K. Kajiwarab, Y. Odab,

J. Hoseac, R. Ellisc, W. Namkungd and M. H. Chod

a National Fusion Research Institute, Daejeon, Koreab Japan Atomic Energy Agency, Naka, Japan

c Princeton Plasma Physics Laboratory, Princeton, USA d Department of Physics, POSTECH, Pohang, Korea

E-mail : [email protected]

8th IAEA TM on Steady State Operation of Magnetic Fusion Devices, May. 29, 2015, NARA, JAPAN

- 2 -8th IAEA TN on SSO for magnetic fusion devices (May. 29, 2015, NARA, Japan)

OUTLINE

Introduction

Progress in conditioning for 170GHz gyrotron

Upgrade activities of KSTAR ECH system in 2014• extension of pulse duration for 170GHz gyrotron • upgrade of launcher mirror for Steady-state operation

Summary

Future plan


Introduce: Layout of KSTAR ECH system in 2014110GHz, loaned from GA (Aug. 2009)

• 0.3MW/2s (max.)• Assisted startup & on-axis heating• X2 mode at BT=1.4~2.4 T

170GHz, loaned from JAEA (Jun 2011)• 1.0MW/50s (max.)• on-axis heating & On/off-axis CD• X2 at BT~3.0 T, X3 at BT~2.0 T

Evacuated 63.5mm ID corrugated WG (~70m)

Actively water-cooled mirror:1MW SS (170GHz)

1ch equatorial launcher with passively cooled mirror: 1MW/15s


Achievements of plasma current and pulse length in KSTAR since the First Plasma

4

2008 (100kA,#794)

2009 (320kA,#2048)

2010 (500kA, 5s, #3862)

2011 (600kA, 12s, #6388)

2012 (600kA, 20s, #7883)

2012 (900kA, 8s, #7200)

2013 (600kA, 21s, #9388)

2014 (600kA, 45s, #11660)

2014 (500kA, 47s, #11664)

2014 (1000kA, 17s, #11721)

Since the first plasma, huge efforts To increase the plasma current

toward MA and the pulse length toward 50 s

as well

0.8MW 170GHz ECH (2011~ ) used as main ECH & supported long-pulse discharge of KSTAR • Therefore, long-pulse operation of

entire EC system required in 2014

0.4MW/2sed 84GHz ECH &0.3MW/2sec 110GHz ECH used for pre-ionization & assisted startup


OUTLINE

Introduction

Progress in conditioning for 170GHz gyrotron

Upgrade activities of KSTAR ECH system in 2014• extension of pulse duration for 170GHz gyrotron • upgrade of launcher mirror for Steady-state operation

Summary

Future plan


170GHz gyrotron (TE31,12 mode) is working at NFRI

June, 2011 @ JAEA July, 2011 @NFRI Sept., 2011 @NFRI


Issue & Progress in conditioning for 170 GHz gyrotron since 20112011(0.75MW/10s/31%)

Successful demonstration of 170GHz EC beam to plasma

24% of flux saving by 0.6 MW 20-deg co-CD injection (et al., Jeong, FEC2012)

Issue ActionInstallation & RF generation

Investigation of operation parameters


Issue & Progress in conditioning for 170 GHz gyrotron since 2011

Issue Action

High power &high efficiency

Optimized parameter scan 2nd beam & magnet alignment

2011(0.75MW/10s/31%) 2012 & 2013 (1MW/20s/40%)

V_cpd (23 kV)V_anode (-5.5 kV)

V_cathode (-49 kV)

I_beam (~53 A)

RF power

(curr. drop from 53 A to 45 A due to the cathode cooling)



1 sec.5 sec.

20 sec pulse


OUTLINE

Introduction

Upgrade activities of KSTAR ECH system in 2014- Progress of Gyrotron conditioning- Upgrade of ECH launcher mirrors- RT EC injection timing & mirror position control by PCS

successful demonstration of NTM feedback control

Summary

Future plan


Requirement and upgrade for 170GHz ECH in 2014

Requirements Upgrades (Enhancement of performance)I. Long-pulse with high power injection

(target operation was 50 sec)

II. RT control of ECH power & target position (will be applied for NTM control)

Long pulse operation of Gyrotron with 1MW/50sec (collaboration with JAEA)

Launcher mirror upgraded for steady-state operation with water-cooled mirrors (collaboration with PPPL)

RT control of EC power (using anode control) & mirror position control implemented on KSTAR PCS (to apply MHD control)



Issue in 2014 ActionLimitation of pulse duration (due to cathode cooling effect)

Anode voltage feed-back control Heater voltage controlDevelopment of water-cooled mirrors

Main mode Pj changes (mode conversion) by decrease of Ibeam

2014 (1MW/50s/40%)

jbeambeam21j PI)VP,(P

dtdP

j

Issue Action

High power &high efficiency

Optimized parameter scan 2nd beam & magnet alignment

2011(0.75MW/10s/31%) 2012 & 2013 (1MW/20s/40%)



I_beam (~53 A)

(curr. drop from 53 A to 45 A due to the cathode cooling)


# 103: VAK control# 106: No VAK control

≈ ≈ ≈

VAK: 44.4 45.6 kV

VAK: no control

Power [kW](@ VDETECTOR)

IBEAM

Mode shift

Maximum pulse duration was 30 sec.Additional heater control required!!

VAK control

I. Anode voltage (VAK) control at highest power condition

# 129: w/o heater control# 139: heater control

25 sec pulse ≈ ≈

II. Pre-heating prior to pulse added to extend pulse length (with anode voltage control)

≈

VHEAT: 25.7 V

VHEAT: 28 V/30 sec over heating prior 1 minutes

Power [kW](measured at diode detector)

VK: 48.0 kVVBODY: 24.0 kV

IBEAM

≈

VAK control

Extension of pulse-duration at high-power regime(collaboration with JAEA)


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 IBEAM~ 50 A

Channels ∆T [deg.] Power [kW]

Fraction[%]

Dummy load 20 743 91%Pre-load 10 44 5.5%MOU chamber 12 18 2%

Dc break 25 11 1%Window 0.7 1 0.5%

Calorimetric power measurement (all of water cooling temperature saturated)

RF power: 0.8 MW avg.

Beam current:not stabilized even for overheating during pulse

Vac. Ion curr. 1.5×10-6 A max.

Collector surface temp.

VAK control

RF power (calorimetric method)

53 A 41 A

Dummy load

(June 03, 2014)

over heating during a pulseVHEATER: 28V

1 MW/50 sec operation of 170GHz gyrotron(collaboration with JAEA)


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)

Upgraded with water-cooled mirrors in 2014:- 1MW for CW operation- 1.2MW 170GHz EC beam assumed for thermal

analysis (190W/cm2 Bessel squared heat flux distribution, 30W/cm2 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

Max. temp. increased to 91ºC for steering mirror[J. W. Han]

steerable mirror

Shutter

Water cooling pipe

bellows

fixed mirror

Laser welding

Rectangular shape of water coolant path


Successful operation of water-cooled mirrors for 2014 KSTAR plasma

41 sec EC beam delivered to KSTAR to support the highβ & long-pulse operation of KSTAR• ∆T of water cooling for mirrors are saturated at 2.6ºC • Power loss: 1.40kW (=190W/cm2) for steering mirror &

1.28kW (=170W/cm2) for fixed• Heat flux from the plasma obtained using ∆P of both

mirrors and it was ~1.6W/cm2

• 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 (∆T~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 !!

ECH: ~41 sec

Saturation of ΔT

Max. Temp of T/L: ~ 32°C (ΔT~10°C)

Max. Temp of MOU: ~50°C (ΔT~25°C)

KSTAR shot 10538

TC sensors

Measurement of surface temperature for T/L by TC sensors

MOU

Gyrotron


EC injection & mirror control by PCS

arbitrary modulation

ECE

Mirror position scanning in poloidal

(Heating Integrated control system)

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


Variation of injection angle & modulation freq. during a pulse

17

KSTAR shot #10997Pnbi ~ 2.4 MW, Pech ~ 0.75 MW (Off-axis X2 170 GHz co-ECCD, Bt = 2.7 T)

<ne>

ECE [keV]

Beam position change in poloidal at the resonance [cm]


Demonstration of NTM control[et al., M. H. Woo]

EC power injection

Mode amplitude

Critical amplitude

Search & suppress

Mode amplitude

Active q tracking

shot # 10566

MHD control start up

shot # 11313

Search & suppress algorithm is working correctly Active q tracking algorithm is working correctly Power is injected above the threshold amplitude

Critical amplitude


Summary & future plan Long pulse operation of 170 GHz ECH/CD system in KSTAR

• Oscillation of 1MW for 50sec was obtained using VAK 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


Near-term future plan (before 2015 campaign)

• Current water-cooled steerable mirror will be upgraded with flexible short-bellows type of mirror to avoid high-tension force from the water-pipes

• Current passive-cooled mirror will be replaced with new water-cooled mirror for steady-state operation

Target in 2015 (1MW/ ?? sec/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


2014 2015 2016 2017

EC Power 170GHz, 1MW, 50s

170GHz, 1MW, 100s105/140GHz, 1MW

170GHz, 1MW105/140GHz, 2MW

170GHz, 1MW (return to JAEA)105/140GHz, 3MW

Launcher 1MW 2set 1MW 2set &Design of two beam launcher (2MW)

1MW 2set &2MW 1set (Fabrication of two beam launcher)

1MW 2set &2MW 1set

Speed Motor design 10 degree/sec

Fast moving system> 50 degree/sec > 50 degree/sec > 50 degree/sec

Power cap. Steady-state Steady-state Steady-state Steady-state

Upgrade plan of KSTAR ECH system


Room for HV PS

105/140GHz dual freq. gyrotron

New 3 MW ECH upgrade plan

110GHz/300kW(2s)

170GHz/1MW(50s)

Evacuated 31.75 mm ID corrugated waveguide (~40 m)

Evacuated 63.5 mm ID corrugated waveguide(~70 m)

N port1MW SS (105/140GHz)

E port1MW SS (170GHz)+ New 2-beam, 2 MW SS (105/140GHz)

New 3 gyrotrons (1MW, 300 s, 105/140 GHz dual

freq.)

Dash lines:New waveguides(63.5 mm ID)

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)


National Fusion Research Institute realizes Green Korea getting joinedwith human beings, environment and technology

23

Thank you for your attention !


Introduction: Mission of KSTAR

• Long term operation plan of KSTAR (presented by Y. K. Oh)

• The mission of the KSTAR is to develop a steady-state-capable advanced superconducting tokamak to establish a scientific and technological basis for an attractive fusion reactor (G.S. Lee, NF 41 (2001))


Repair of water-load

1 MW CWdummy load

(loaned from JAEA)Pre-load

ECH power

Worn-out of stem due to the friction between the seal and rotating stem

I. Water leak at the rotating stem

Dummy load inside

II. TiO2 coating melted away on the surface of dummy load




Gyrotron

Matching optics unit

SCM

Gun oil tank

HV in

T/L

2011(0.75MW/10s/31%)


ECH-assisted startup


Bellows



Issue Action

Installation & RF generation

ECH-assisted startup

2011(1MW/10s/40%) 2012 & 2013 (1MW/20s/40%) 2014 (1MW/50s/40%)

24% of flux saving by 0.6 MW 20-deg co-CD injection

Documents

Operational progress of 1MW ECH system in KSTAR Meeting... · 8th IAEA TN on SSO for magnetic fusion devices (May. 29, 2015, NARA, Japan) -3- Introduce: Layout of KSTAR ECH system