HL-2A Lisboa, Portugal 22 to 24 October, 2007 Dong Yunbo Recent Experiment Results during electron cyclotron heating 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 of main author: Southwestern Institute of Physics (SWIP), Chengdu, China 17 th IAEA Technical Meeting on Research Using Small Fusion Devices

HL-2A Lisboa, Portugal 22 to 24 October, 2007 Dong Yunbo Outline  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

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 Outline

HL-2A Lisboa, Portugal 22 to 24 October, 2007 Dong Yunbo HL-2A Tokamak Physics issues on HL-2A  Transport: thermal transport, particle transport, impurity 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 m -3 Electron temperature: 5.0k eV Ion temperature:600 eV

HL-2A Lisboa, Portugal 22 to 24 October, 2007 Dong Yunbo Layout of HL-2A Tokamak SMBI Pellet Injection 2*500kW /1s /68GHz ECRH/ECCD 1.5MW/50keV/2sN BI system 2*500kW/1s /68GHz ECRH/ECCD 2*500kW /1S /2.45GHz LHCD system Thomson Scattering CXRS 8-Channel HCN interferometer VUV spectrometer MW reflectometer ECE Fast scan probes Neutral Particle Analyzer SDD soft X ray spectrum Bolometer & Soft X ray arrays Other Diagnostics, … …

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;

HL-2A Lisboa, Portugal 22 to 24 October, 2007 Dong Yunbo r/a = 0 r/a = 0.4 Te increasing Density pump-off Radiation increasing H alpha inceasing ECRH Radiation increasing ECH experiments

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 Outline

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 LN 2 output LN 2 inlet Turbo Pump Arrangement for SMBI in the HL-2A  Gas pressure: 1 M Pa to 3 M Pa  Pulse duration of Jet : 2 ms  Pulse interval: 50 ms to 100 ms

HL-2A Lisboa, Portugal 22 to 24 October, 2007 Dong Yunbo During ECRH a series pulse SMBI fueling, the plasma storage energy W E, 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 MPa Pulse number: 10, later 5 pulses during ECRH Pulse duration: 0.3 ms Pulse interval: 50 ms ECRH Power: 1034 kW ECRH 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

HL-2A Lisboa, Portugal 22 to 24 October, 2007 Dong Yunbo Outline  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

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=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.

HL-2A Lisboa, Portugal 22 to 24 October, 2007 Dong Yunbo Non-local transport phenomena  Happened in low density range （ ne~1-2x10 13 cm -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.

HL-2A Lisboa, Portugal 22 to 24 October, 2007 Dong Yunbo Outline  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

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 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.

HL-2A Lisboa, Portugal 22 to 24 October, 2007 Dong Yunbo Reduced core transport after ECRH switch-off Steep SX profile Nearly unchanged T e0 n e 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

HL-2A Lisboa, Portugal 22 to 24 October, 2007 Dong Yunbo Outline  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

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 ( P ECH =450kW); (b) off-axis ECH (P ECH =340kW) 20 normal larger smaller double saturated giant hill humpback

HL-2A Lisboa, Portugal 22 to 24 October, 2007 Dong Yunbo Non-standard sawtooth during ECRH  Double Sawtooth  Compound(saturated+double)Sawtooth m=1 island SVD m=1island SVD 21

HL-2A Lisboa, Portugal 22 to 24 October, 2007 Dong Yunbo 22 Heating effect during crash or reconnection Possible explanation: hillshumpback The Te growth in both case corresponds to some temporary improvement of the global confinement Non-standard sawtooth during ECRH

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=2.0×10 19 m -3, Pecrh=1100kW, r q=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: P ECRH =1393kW, Bt=2.24T, r’=-14cm, Ne=2.4×10 19 m -3, r q=1 =12cm(obtained from SVD) ， deposion location is just outside the q=1 surface.

HL-2A Lisboa, Portugal 22 to 24 October, 2007 Dong Yunbo Outline  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

HL-2A Lisboa, Portugal 22 to 24 October, 2007 Dong Yunbo Fast particle driven instabilities: Fishbones Low field side deposition P ECRH =650kW High field side deposition P ECRH =280kW f （ kHz ） wavelet spectrum Fishbone like instabilities Crash m=1/n=1 “fishbone like instaility” exited with  Electron density < 3x10 13 cm -3  Power of ECRH < 900kW  Both high field side and low field side deposition

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 Normalized precession velocity of circulating electrons 30 – 60 keV 10 –30 keV

HL-2A Lisboa, Portugal 22 to 24 October, 2007 Dong Yunbo Future plan in ECRH/CD experiment on HL-2A  Confinement 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

HL-2A Lisboa, Portugal 22 to 24 October, 2007 Dong Yunbo Thank you for attention!