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SW IP
HL-2A
Lisboa, Portugal 22 to 24 October, 2007 Dong Yunbo
Recent Experiment Results Recent Experiment Results during electron cyclotron during electron cyclotron
heating on HL-2Aheating on HL-2A
Y.B.Dong, Y.Liu, H.J.Sun, W. Chen, W.W.Xiao, J. Zhou, W. Deng, L.H.Yao, B.B.Feng, J.Rao , Q.W.Yang , X.T.Ding , Yong Liu , and C.H.
Pan
E-mail of main author: [email protected]
Southwestern Institute of Physics (SWIP), Chengdu, China
17th IAEA Technical Meeting on Research Using Small Fusion Devices
SW IP
HL-2A
Lisboa, Portugal 22 to 24 October, 2007 Dong Yunbo
OutlineOutline ECRH experiment on HL-2A
Experiment results on HL-2A
Confinement enhancement by SMBI during ECRH
Non-local transport phenomena induced by SMBI
Reduced core transport after ECRH switch-off
Sawtooth behaviour during ECRH
Exiting of the m=1/n=1 mode during ECRH
Future plan in ECRH/CD experiment on HL-2A
SW IP
HL-2A
Lisboa, Portugal 22 to 24 October, 2007 Dong Yunbo
ECRH experiment on HL-2A
Experiment results on HL-2A
Confinement enhancement by SMBI during ECRH
Non-local transport phenomena induced by SMBI
Reduced core transport after ECRH switch-off
Sawtooth behaviour during ECRH
Exiting of the m=1/n=1 mode during ECRH
Future plan in ECRH/CD experiment on HL-2A
OutlineOutline
SW IP
HL-2A
Lisboa, Portugal 22 to 24 October, 2007 Dong Yunbo
HL-2A Tokamak
Physics issues on HL-2APhysics issues on HL-2A Transport: thermal transport, particle transport, im
purity transport, … SOL and divertor: Edge and pedestal physics: MHD and disruptions: NTM, ELMs, TAEs, … Turbulence: Zonal Flows Confinement and advanced scenarios: H-mode, …
Main parameters of HL-2A
•Major radius: 1.65 m•Minor radius: 0.40 m•Toroidal field: 2.8 T-3.5T•Plasma current: 480 kA•Magnetic flux: 5.0 Vs•Discharge duration:1.5 sec.•Plasma density: 4.2 x 1019 m-3
•Electron temperature: 5.0k eV•Ion temperature: 600 eV
SW IP
HL-2A
Lisboa, Portugal 22 to 24 October, 2007 Dong Yunbo
Layout of HL-2A Tokamak
SMBISMBIPellet InjectionPellet Injection
2*500kW 2*500kW /1s /68GHz /1s /68GHz ECRH/ECCDECRH/ECCD
1.5MW/1.5MW/50keV/2sNBI 50keV/2sNBI systemsystem
2*500kW/2*500kW/1s /68GHz 1s /68GHz ECRH/ECCDECRH/ECCD
2*500kW 2*500kW /1S /1S /2.45GHz /2.45GHz LHCD LHCD systemsystem
Thomson Thomson ScatteringScattering
CXRSCXRS
8-Channel HCN 8-Channel HCN interferometerinterferometer
VUV spectrometerVUV spectrometer
MW reflectometerMW reflectometer
ECEECE
Fast scan probesFast scan probes
Neutral Neutral Particle Particle AnalyzerAnalyzer
SDD soft X ray SDD soft X ray spectrumspectrum
Bolometer & Soft X ray Bolometer & Soft X ray arraysarrays
Other Diagnostics, … …Other Diagnostics, … …
SW IP
HL-2A
Lisboa, Portugal 22 to 24 October, 2007 Dong Yunbo
The fundamental O-mode EC wave with the wide steering angles in poloidal (~25º) and toroidal (~25º) directions
The ECW launched from 2 equatorial ports, 4 gyrotrons
The maximum power is 2 MW (1.7 MW in experiments)
ECRH systerm
Transmission line
corrugated waveguide, miterbends, DC breaks;
Launcher
focusing mirrors, steering mirrors;
SW IP
HL-2A
Lisboa, Portugal 22 to 24 October, 2007 Dong Yunbo
r/a = 0r/a = 0
r/a = 0.4r/a = 0.4
Te increasing
Density pump-off
Radiation increasing
H alpha inceasing
ECRH
Radiation increasing
ECH experiments
SW IP
HL-2A
Lisboa, Portugal 22 to 24 October, 2007 Dong Yunbo
ECRH experiment on HL-2A
Experiment results on HL-2A
Confinement enhancement by SMBI during ECRH
Non-local transport phenomena induced by SMBI
Reduced core transport after ECRH switch-off
Sawtooth behaviour during ECRH
Exiting of the m=1/n=1 mode during ECRH
Future plan in ECRH/CD experiment on HL-2A
OutlineOutline
SW IP
HL-2A
Lisboa, Portugal 22 to 24 October, 2007 Dong Yunbo
SMBI on HL-2A
The SMBI with clusters may be of benefit for deeper fuelling
Stair-shaped density increments
The plasma density increases after MBI, while a temperature drop was observed in the central ECE channel.
H2 inlet
CCD Camera
SMB Valve
Hα Array 1
Hα Array 2
Separatrix
Lower divertor
Target plate
LN2 output
LN2 inlet
Turbo Pump
Arrangement for SMBI in the HL-2AGas pressure: 1 M Pa to 3 M PaPulse duration of Jet : 2 msPulse interval: 50 ms to 100 ms
SW IP
HL-2A
Lisboa, Portugal 22 to 24 October, 2007 Dong Yunbo
During ECRH a series pulse SMBI fueling, the plasma storage energy WE, Beta_p, line averaged density ne and “fusion neutron” account increase, the plasma confinement was improved.
Confinement enhancement by SMBI during ECRH
Gas pressure of D2: 2.0 MPaPulse number: 10, later 5 pulses during ECRHPulse duration: 0.3 msPulse interval: 50 msECRH Power: 1034 kWECRH duration: from 800 ms to 1200 ms
neutron account
spring
Laval nozzle
valve
piston
inlet outlet
A new pneumatic supersonic molecular beam injector is developing to realize the SMBI from HFS, which will be beneficial to deeper injection and higher fuelling efficiency.
SMB Injector
SW IP
HL-2A
Lisboa, Portugal 22 to 24 October, 2007 Dong Yunbo
OutlineOutline ECRH experiment on HL-2A
Experiment results on HL-2A
Confinement enhancement by SMBI during ECRH
Non-local transport phenomena induced by SMBI
Reduced core transport after ECRH switch-off
Sawtooth behaviour during ECRH
Exiting of the m=1/n=1 mode during ECRH
Future plan in ECRH/CD experiment on HL-2A
SW IP
HL-2A
Lisboa, Portugal 22 to 24 October, 2007 Dong Yunbo
high field side
Ha and radiation losses drop ( Enhanced energy confinement )
Non-local transport phenomena induced by SMBI
15
q=2q=2
(PECRH = 800 kW, TSMBI = 810 ms)
After the injection of SMB, outside r~20cm the plasma is cooled while the core Te increase. A steep Te profile in the plasma core is sustained for about 40ms. Meanwhile the radiation of bolometer and Ha decrease.
SW IP
HL-2A
Lisboa, Portugal 22 to 24 October, 2007 Dong Yunbo
Non-local transport phenomena
Happened in low density range ( ne~1-2x1013cm-3 ) Located between q=1 and q=2 surface
Central temperature increase of 200ev
Duration of the process is longer: the effect lasts about 5ms in RTP, it is about 40ms in HL-2A
Radiation of bolometer and Ha decrease in HL-2A, there is no sign of the decrease in RTP
The non-local effect appears after the injection of the latter two SMBs during ECRH and OH, while the first one doesn’t induce such an effect. The effect always occurs with low density and the density limit is larger during ECRH.
SW IP
HL-2A
Lisboa, Portugal 22 to 24 October, 2007 Dong Yunbo
OutlineOutline ECRH experiment on HL-2A
Experiment results on HL-2A
Confinement enhancement by SMBI during ECRH
Non-local transport phenomena induced by SMBI
Reduced core transport after ECRH switch-off
Sawtooth behaviour during ECRH
Exiting of the m=1/n=1 mode during ECRH
Future plan in ECRH/CD experiment on HL-2A
SW IP
HL-2A
Lisboa, Portugal 22 to 24 October, 2007 Dong Yunbo
Steep SX profile
Te increase
Reduced core transport after ECRH switch-off
23
Delayed Te decrease
Off-axis ECRH
0
20
40
60
15 17 19 21 23 25 27
r( cm)
Xe(c
m2/m
s)
OHECRHj ust af ter ECRH
Power deposition location
The central Isx remains constant for some times after ECRH switch off, while the off-axis Isx decrease, ▽Te increase and the transport coefficients reduce.
SW IP
HL-2A
Lisboa, Portugal 22 to 24 October, 2007 Dong Yunbo
Reduced core transport after ECRH switch-off
Steep SX profile
Nearly unchanged Te0
ne increase slightly
Off-axis ECRH switch-off leads to current density redistribution and transiently low shear, causing a local confinement improvement.
Possible explanation:
Larger sawtooth
SW IP
HL-2A
Lisboa, Portugal 22 to 24 October, 2007 Dong Yunbo
OutlineOutline ECRH experiment on HL-2A
Experiment results on HL-2A
Confinement enhancement by SMBI during ECRH
Non-local transport phenomena induced by SMBI
Reduced core transport after ECRH switch-off
Sawtooth behaviour during ECRH
Exiting of the m=1/n=1 mode during ECRH
Future plan in ECRH/CD experiment on HL-2A
SW IP
HL-2A
Lisboa, Portugal 22 to 24 October, 2007 Dong Yunbo
Sawtooth behaviour during ECRH
A sawtooth tends to saturate or decrease in its ramp phase, and the sawtooth shape is usually changed, leading to formation of a saturated sawtooth, a compound sawtooth, a humpback or a hill.
The auxiliary heating power is up to 2MW in the ECRH experiment of HL-2A tokamak. on-axis ECH (with a more peaked profile)off-axis ECH (with flat profile, no “hot ears”)
(a) on-axis ECH ( PECH=450kW);
(b) off-axis ECH (PECH=340kW)
20
normal
larger
smaller
double
saturated
giant
hill
humpback
SW IP
HL-2A
Lisboa, Portugal 22 to 24 October, 2007 Dong Yunbo
Non-standard sawtooth during ECRH
Double Sawtooth
Compound(saturated+double)Sawtooth
m=1 islandSVD
m=1islandSVD
21
SW IP
HL-2A
Lisboa, Portugal 22 to 24 October, 2007 Dong Yunbo 22
•Heating effect during crash or reconnection
Possible explanation:
hills humpback
The Te growth in both case corresponds to some temporary improvement of the global confinement
Non-standard sawtooth during ECRH
SW IP
HL-2A
Lisboa, Portugal 22 to 24 October, 2007 Dong Yunbo
axisq=1 surface
25
The most significant response to a change in the heating location is the rapid change in sawtooth shape and period as the heating location crosses the inversion surface.
Stabilization of sawtooth activity–giant sawtooth
Ne=2.0×1019m-3, Pecrh=1100kW, rq=1 = 11cm,
The maximum sawtooth period is obtained for power deposition close to the HFS q=1 surface, located at 9.8cm. The sawtooth periods are smaller near the axis.
Large sawtooth: PECRH=1393kW, Bt=2.24T, r’=-14cm, Ne=2.4×1019m-3, rq=1=12cm(obtained from SVD), deposion location is just outside the q=1 surface.
SW IP
HL-2A
Lisboa, Portugal 22 to 24 October, 2007 Dong Yunbo
OutlineOutline ECRH experiment on HL-2A
Experiment results on HL-2A
Confinement enhancement by SMBI during ECRH
Non-local transport phenomena induced by SMBI
Reduced core transport after ECRH switch-off
Sawtooth behaviour during ECRH
Exiting of the m=1/n=1 mode during ECRH
Future plan in ECRH/CD experiment on HL-2A
SW IP
HL-2A
Lisboa, Portugal 22 to 24 October, 2007 Dong Yunbo
Fast particle driven instabilities: Fishbones
Low field side deposition PECRH =650kW
High field side deposition PECRH=280kW
•0.4
•0.5
• f(kHz)
•wavelet spectrum
•700 •705 •710 •715 •720 •725 •730
•5
•15
•20
•10
Fishbone like instabilities
Crash
m=1/n=1 “fishbone like instaility” exited with
Electron density < 3x1013cm-3
Power of ECRH < 900kW
Both high field side and low field side deposition
SW IP
HL-2A
Lisboa, Portugal 22 to 24 October, 2007 Dong Yunbo 32
Destabilizing effect of suprathermal electrons
Increase of hard X ray during ECRH
Electron fishbone excited by the barely trapped electrons(Procession reversal )(Ding X.T,Liu Yi,Nuclear Fusion Vol.42,No5(2002)491)
Electron fishbone excited by the circulating electrons
Z.T.Wang,Nuclear Fusion47
0.0 0.2 0.4 0.6 0.8 1.0
-0.4
-0.2
0.0
0.2
s=-0.1 s=-0.02 s=0 s=0.02 s=0.1
Gc
k
Normalized precession velocity of circulating electrons
30 – 60 keV
10 –30 keV
SW IP
HL-2A
Lisboa, Portugal 22 to 24 October, 2007 Dong Yunbo
Future plan in ECRH/CD experiment on HL-2AConfinement enhancement with ECRH ( H-mode )
Transport study with ECRH
ITB formation;
Non-local transport phenomena
Electron heat transport and ECRH modulation experiments
MHD study with ECRH/CD
Correlation between MHD activities and ITB emergence
Control of NTM mode by controlling of sawtooth period
Exiting of the e-fishbone during ECRH
46
Future plan in ECRH/CD experiment on HL-2A