recent results of kstar h-modes, elm mitigations and tm stabilisation yong-su na on behalf of the...
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![Page 1: Recent Results of KSTAR H-modes, ELM Mitigations And TM stabilisation Yong-Su Na on behalf of the KSTAR Team](https://reader035.vdocuments.pub/reader035/viewer/2022062722/56649f2b5503460f94c45a61/html5/thumbnails/1.jpg)
Recent Results of KSTARH-modes, ELM Mitigations
And TM stabilisation
Yong-Su Na on behalf of the KSTAR Team
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Contents
• Short introduction to KSTAR
• H-modesL-H transition power threshold
Characteristics of H-mode discharges
Effect of ECRH on rotation
• Control of Edge Localized ModesEffect of resonant magnetic perturbation
Direct pedestal heating by ECRH
ELM mitigation by SMBI
ELM pacemaking by Vertical jog
• Control of Tearing Modes
2
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To achieve the superconducting tokamak construction and operation experiences, and
To develop high performance steady-state operation physics and technologies that are essential for ITER and fusion reactor development
Major radius, R0
Minor radius, a
Elongation, Triangularity, Plasma volume
Bootstrap Current, fbs
PFC Materials
Plasma shape
Plasma current, IP
Toroidal field, B0
Pulse length
N
Plasma fuel
Superconductor
Auxiliary heating /CD
Cryogenic
PARAMETERS
1.8 m
0.5 m
2.0
0.8
17.8 m3
> 0.7
C, CFC (W)
DN, SN
2.0 MA
3.5 T
300 s
5.0
H, D
Nb3Sn, NbTi
~ 28 MW
9 kW @4.5K
Designed
1.8 m
0.5 m
2.0
0.8
17.8 m3
-
C
DN
1.0 MA
3.6 T
10 s
> 1.5
H, D, He
Nb3Sn, NbTi
2.0 MW
5 kW @4.5 K
Achieved
KSTAR Parameters
• Black : achieved• Red : by 2011
KSTAR Mission
KSTAR Mission and Achievements
3
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NBI-1100 keV
1.5 MW, 10 s
PFC Baking & Cooling200 C
Cryogenic helium supply4.5 K, 600 g/s
vacuum pumpingECH
84 GHz / 110 GHz0.3 MW, 2 s
ECH170 GHz
0.7 MW, cw
KSTAR Device for 2011 Campaign
ICRF0.5MW, 1s
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Contents
• Short introduction to KSTAR
• H-modesL-H transition power threshold
Characteristics of H-mode discharges
Effect of ECRH on rotation
• Control of Edge Localized ModesEffect of resonant magnetic perturbation
Direct pedestal heating by ECRH
ELM mitigation by SMBI
ELM pacemaking by Vertical jog
• Control of Tearing Modes
5
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60.2 1.2 2.20
0.5
1
1.5
beta
p
time[s]
0
500
Wto
t
0
1000
2000
EC
E [
a.u.
]
0
5
Ha
[a.u
.]
0
2
4
n e [10
19 m
-3]
0
0.5
1
Pex
t [M
W]
0
0.5
I p [M
A]
PNBI
PECRH
midplane
divertor
R=1.67 m (core)
R=1.35 m (edge)
0.2 1.2 2.20
5
10
q95
time[s]
0
1li
0
0.5
delta
bot
1
1.5
2
kapp
a
• ~30 shots achieved in 5 days• BT = 2 T, Ip ~ 0.6 MA, ne ~ 2e19 m-3
• PNBI ~ 1.3 MW (80 keV, co-NBI)• PECH ~ 0.25 MW (cntr-injection to Ip)• POH ~ 0.2 MW• Double null, κ ~ 1.8, R ~ 1.8 m, a ~ 0.5 m• Boronization with carborane• Pthres ~1.1 MW (ITER physics basis,
1999)
ELMs
~80% increase of βp
sharp increase of edge ECE
H-mode#4333
Da
Typical H-mode in KSTAR (2010)
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7
Roll-over of H-mode threshold power at low density
𝐏𝐭𝐡𝐫 , 𝐬𝐜𝐚𝐥𝐢𝐧𝐠=𝟎 .𝟎𝟒𝟖𝟖±𝟎 .𝟎𝟎𝟐𝟖𝐧𝐞𝟐𝟎𝟎.𝟕𝟏𝟕±𝟎.𝟎𝟑𝟓𝐁𝐓
𝟎.𝟖𝟎𝟑±𝟎.𝟎𝟑𝟐𝐒𝟎 .𝟗𝟒𝟏 ±𝟎 .𝟎𝟏𝟗
Progress in ITER Physics Basis (2007)
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8
E estimated using measured stored energy and ASTRA simulation with some assumptions
Assuming 20% (due to low density regime) fast ion fraction in the stored energy, the experimental E was estimated L-mode: E= ~86ms, HL96=1.3 H-mode: E=~130ms, HH98=1.1
a)
b)
dtdWPPPPP
PWW fast
totfastionradauxOhmloss
losstotE,exp )(
Energy Confinement Time is in Line with Multi-Machine Database for L- and H-mode
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9
Extended Operation Boundary to high βN
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10
Structure of pedestal from CES measurementsPedestal width is larger for VT
Width of Ti ~2.5 cm
Width of VT ~3.5 cm
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11
ECH effect on toroidal rotation in H-mode(by XICS measurements)
Core Ti drop
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12
Rotation drop is larger for the central region
CES measurements
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13
Smaller counter torque with off-axis ECH
Scan of ECH deposition layer
Smaller drop of Ti
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Contents
• Short introduction to KSTAR
• H-modesL-H transition power threshold
Characteristics of H-mode discharges
Effect of ECRH on rotation
• Control of Edge Localized ModesEffect of resonant magnetic perturbation
Direct pedestal heating by ECRH
ELM mitigation by SMBI
ELM pacemaking by Vertical jog
• Control of Tearing Modes
14
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15
Courtesy by G.S. Yun (Postech) and J.G. Bak(NFRI)PRL 2011
A single large ELM crash was composed of a series of multiple filament bursts
Similar observations on ion satura-tion currents measured from diver-tor probes
KSTAR #4362
Time [sec]
Inner Diver-tor (EP 42)
Outer Divertor (EP 54)
2D ECEI Observation: A Single Large ELM Crash Event Consisted of A Series of Multiple Filament Bursts
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16
Suppression of ELMs withn=1 Resonant magnetic perturbations
Top-RMPMid-RMPBot-RMP
BT=2.0TPNBI=1.4MW
• 90 phasing RMP strongly mitigated or suppressed ELMs- In JET, ELM mitigated by n=1 (Y.Liang, PRL, 2007)
• Two distinctive phases observed(1)ELM excitation phase(2)ELM suppression phase
• Density (~10%) pumping out initially. Then, increasing when ELM sup-pressed
• Stored energy drop by ~8% initially. Then slightly increased or sustained when ELM suppressed
• Rotation decreased (~10%) initially. Then sustained when ELM suppressed
• Te/Ti changes were relatively small
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Strong locking observed instead of ELM-Suppres-sion at relatively high edge Te
17
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Direct ECH in the pedestal region
Optimal edge heatingat BT0 = 2.3 T
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192.2 2.4 2.6 2.8 3 3.2 3.4 3.6
100
150
200
250
VT [
km/s
]
time[s]
0.7
0.8
0.9
1
p
1.5
2
2.5
3
nel [
1019
/m3 ]
0
5
10
D [
a. u
.]
0
0.5
1
1.5
Pex
t [M
W]
PECH
110 GHz
PECH
170 GHz
PNBI
ECH near pedestal increases fELM
Shot 6313At relatively low ν*fELM before ECH ~20~30 HzfELM during ECH ~40 HzfELM after ECH ~20~30 Hz
Clear ne & VT dropSimilar W△ ELM
No clear effect of ECCD
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20
0 1 2 3 4 5 6-100
0
100
200
VT [
km/s
]
time[s]
0.4
0.6
0.8
1
p
0
2
4
nel [
1019
/m3 ]
0
5
10
D [
a. u
.]
-1
0
1
2
Pex
t [M
W]
PECH 110 GHz
PECH
170 GHz
PNBI
4.55 4.6 4.65 4.7 4.75 4.8 4.85 4.9 4.95
500
550
600
Te
edge
[eV
]
time[s]
110
120
130
140
VT [
km/s
]
0.75
0.8
0.85
p
2.6
2.8
3
nel [
1019
/m3 ]
0
5
10
D [
a. u
.]
00.20.40.60.8
Pex
t [M
W]
Large ELMs are triggered by ECH at relatively high ν*
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21
Mitigation of ELMs with Supersonic Molecular Beam Injection
After SMBI injection, ELM type changed from type-I like to grassy
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ELM pace-making with fast vertical jog
• ~5 mm of vertical excursion trigger ELMs (~3 mm is marginal)• ELM is triggered when plasma moves away with its maximum speed
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Multiple ELMs triggered with larger excursion
In addition to the normal trigger, larger ELMs are triggered when the vertical position is at lower minimum
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Contents
• Short introduction to KSTAR
• H-modesL-H transition power threshold
Characteristics of H-mode discharges
Effect of ECRH on rotation
• Control of Edge Localized ModesEffect of resonant magnetic perturbation
Direct pedestal heating by ECRH
ELM mitigation by SMBI
ELM pacemaking by Vertical jog
• Control of Tearing Modes
24
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25
NTM in KSTAR
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Ip (kA)
NBI (keV)
R (m)
z (m)
κ βp
Vtor (km/s)
Hα
RMP (A)
Time (s) Time (s) Time (s) Time (s)
Te (keV)
Wtot (kJ)NBI (MW)
170 GHz ECH (kW)
110 GHz ECH (kW)
: m/n=2/1 tearing appears#6272
Tearing mode stabilisation experiment
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27
Estimation of Island width from Mirnov coil signals
5.6 5.8 6.0 6.2 6.4 6.6 6.8-15
-10
-5
0
5
10
15
Am
plit
ud
e (a
.u.)
Time (s)
MC1P03FFT
MC1P03
5.6 5.8 6.0 6.2 6.4 6.6 6.80
5
10
15
20
Fre
qu
ency
(kH
z)
Time (s)
FFTanalysis
2/1 mode
4/2 mode
2/1 modetracking
Isla
nd
wid
th (
m)
4.5 4.6
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Determination of Island Location using ECE
core edge
island
R (m)
Isla
nd
wid
th (
m)
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29
Preliminary simulation of the island evolution
- Te From experiment
- ne, ni assumed
- Ti from the Weiland model
Time (s)
Isla
nd
wid
th (
m) exp.
Simul.Ti (keV)
Te (keV)ni (1019m-3)
ne (1019m-3)
Pech (MW/m2)
2/1 island
- Initial width: 0.55 m
- Using a2 = 2
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○ Main Research Direction• Controllable H-mode (> 10 s) at ~1 MA • ITER relevant/urgent physics issues
- ELM mitigation by using RMP, SMBI, ECCD, etc
- IOS-related issues: OPEN!• Supported by Theory and modelling (ex, WCI)
○ Hardware Priority (mission oriented) • NB(+2 MW) -> NB(3.5 MW), LH(0.5 MW), ECH(1 MW)
ICRH(1 MW)• IRC(In-vessel radial control coil) • Thomson(25ch), BES, Reflectometry, Diverter IR
Strategy for 2012 experiments (Pre-liminary)
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• August : Evacuation start • Sep. : Cryo-facility operation and magnet cool-down (300 K ~ 4.5
K)• Sep. : SC magnet and power supply operation• Oct. ~ Nov. : Plasma experiments• Dec. : Closing the experiments and magnet warm-up• (*) During Jan. to July, New NBI installation
Evacuation & Wall conditioning
Magnet cool-down
Plasma experiments
SC magnet operation
Schedule in 2012(tentative)