Longwen Yan, Experimental Progress on HL-2A, 6-8 Jan. 2014, Tsinghua University, Beijing 1/29 HL-2A Southwestern Institute of Physics, Chengdu, China Experimental Progress on HL-2A HL-2A Team (Presented by Longwen Yan) The Second A3 Foresight Workshop on Spherical Torus

Longwen Yan, Experimental Progress on HL-2A, 6-8 Jan. 2014, Tsinghua University, Beijing 2/29 HL-2A  HL-2A tokamak  Diagnostic development  Confinement improvement and transport  Energetic physics and MHD activity  Turbulence and zonal flows  Summary Outline

Longwen Yan, Experimental Progress on HL-2A, 6-8 Jan. 2014, Tsinghua University, Beijing 3/29 HL-2A HL-2A tokamak R:1.65 m a:0.40 m B t :2.7 T I p :450 kA n e :~ 6.0 x m -3 T e :~ 5.0 keV T i :~ 2.8 keV Auxiliary heating systems ECRH/ECCD: 3 MW: 6  0.5 MW/68 GHz/1 s 2 MW: 2  1 MW/140 GHz/3 s Modulated f=10~30 Hz; Amp. 10~100% NBI: 3 MW/55 kV/2 s (5 MW/80keV) LHCD: 2  0.5 MW/2.45GHz (2 MW/3.7GHz) Fuelled system (H 2 /D 2 ): Gas puffing (LFS, HFS, divertor) Extruded PI (40 pellets/LFS, HFS) SMBI (LFS, HFS) LFS: f =10~60 Hz, pulse>0.5ms Gas pressure: MPa HFS: f = 1-5 Hz, MPa

Longwen Yan, Experimental Progress on HL-2A, 6-8 Jan. 2014, Tsinghua University, Beijing 4/29 HL-2A  HL-2A tokamak  Diagnostic development  Confinement improvement and transport  Energetic physics and MHD activity  Turbulence and zonal flows  Summary Outline

Longwen Yan, Experimental Progress on HL-2A, 6-8 Jan. 2014, Tsinghua University, Beijing 5/29 HL-2A Comparison of MSE spectral broadening Simulation parameters Beam dissipation d  ≈1.0° Lens size=37mm Energy dissipation dv=2% Fitted functions I 0 is intensity of central wavelength 0 is Stark splitting at central wavelength and σ is spectral width Jiang N. et al 2013, CPL30,

Longwen Yan, Experimental Progress on HL-2A, 6-8 Jan. 2014, Tsinghua University, Beijing 6/29 HL-2A Profiles of magnetic field pitch angle Radial profiles of magnetic field pitch angles slightly increase with time, indicating current profiles to be peaking gradually

Longwen Yan, Experimental Progress on HL-2A, 6-8 Jan. 2014, Tsinghua University, Beijing 7/29 HL-2A FILD diagnostics successful on HL-2A Shot Bt=1.34 T Frame f=500 fps Probe at R=2.13 m Current flattop during NBI Plasma disruption with NBI Flattop phase: Fast ion loss energy keV and pitch angle Disruption phase: Fast ion loss energy and pitch angle change with magnetic perturbation rather largely.

Longwen Yan, Experimental Progress on HL-2A, 6-8 Jan. 2014, Tsinghua University, Beijing 8/29 HL-2A Pedestal structure during an ELM measured by a new microwave reflectometry with high spatiotemporal resolutions Pedestal structure evolution during ELM

Longwen Yan, Experimental Progress on HL-2A, 6-8 Jan. 2014, Tsinghua University, Beijing 9/29 HL-2A  HL-2A tokamak  Diagnostic development  Confinement improvement and transport  Energetic physics and MHD activity  Turbulence and zonal flows  Summary Outline

Longwen Yan, Experimental Progress on HL-2A, 6-8 Jan. 2014, Tsinghua University, Beijing 10/29 HL-2A Basis of confinement and transport Particle ITB observed in HL-2A for the first time (Xiao W. W. 2010, PRL ) NLT effect induced by SMBI fuelling and ECRH switching off (Sun H.J. et al. 2010, PPCF ; Sun H.J. et al NF 51, ) Turbulence and ELM characteristics (Duan X.R. 2010, NF 50, ; Yan L.W. 2011, NF ) ELM mitigation by SMBI/CJI fuelling succeeded on HL-2A for the first time, and confirmed by KSTAR and EAST (Xiao W. W. et al NF52, ) Duan X.R., NF 49 (2009) Xiao W. W. 2010, PRL Zhong W.L., PoP 17, (2010) Liu Yi, PRE, 84 (2011) Huang Y., NF 52 (2012)114008

Longwen Yan, Experimental Progress on HL-2A, 6-8 Jan. 2014, Tsinghua University, Beijing 11/29 HL-2A ELM mitigated by SMBI successfully n e =1.8~2.3×10 19 m -3 P aux = MW Xiao W. W. et al NF52, Pedestal density gradient drops after SMBI fuelleing, indicating particle confiement degeneration (a)

Longwen Yan, Experimental Progress on HL-2A, 6-8 Jan. 2014, Tsinghua University, Beijing 12/29 HL-2A ELM mitigated by CJI better Cluster jet injection (CJI ） mitigates ELM instability with better effect than SMBI Duan X. R. 2013, NF53,

Longwen Yan, Experimental Progress on HL-2A, 6-8 Jan. 2014, Tsinghua University, Beijing 13/29 HL-2A L-I-H transition by sawtooth crashes L-H transition may be triggered by sawtooth crashes Plasma density and energy increase with time The frequency of I-phase oscillations decrease from 2.2kHz, 1.9kHz to 1.4 kHz. The I-H transition successfully after the fourth sawtooth crash Liu C. H. et al. EPS2013, P5.157 Zhao K. J. et al. NF 53 (2013)

Longwen Yan, Experimental Progress on HL-2A, 6-8 Jan. 2014, Tsinghua University, Beijing 14/29 HL-2A ELM-free H-mode with EHO-like EHO-like mode leads to density rate dropping and turbulent particle flux rising in SOL This mode located near r/a=0.94) with f=5-10 kHz and mode number m/n=3/1 The EHO appears on D  and SXR emission Zhong W. L. 2013, NF53,

Longwen Yan, Experimental Progress on HL-2A, 6-8 Jan. 2014, Tsinghua University, Beijing 15/29 HL-2A Strong particle convection after SMBI Yu D. L. 2012, NF 52, The density at outer channels (Z = -17.5, 24.5 cm) drop after a few milliseconds fuelled by SMBI The density at central region (Z = ±3.5 cm) sustains about 30 ms to be dropping The density gradually peaks after SMBI (h). The results indicate that strongly inward convection exists after SMBI

Longwen Yan, Experimental Progress on HL-2A, 6-8 Jan. 2014, Tsinghua University, Beijing 16/29 HL-2A Impurity transport in Ohmic and ECRH There is a good agreement between the simulation (lines) and the experiments (symbols) results with diffusion D = 0.6 m 2 /s and inner convection V(a) = -1 m/s in Ohmic plasma The strong decrease of the CV intensity compared with CIV in ECRH can only be reproduced with outer convection V(a) = 7 m/s (b) Cui Z. Y. et al 2013, NF 53,

Longwen Yan, Experimental Progress on HL-2A, 6-8 Jan. 2014, Tsinghua University, Beijing 17/29 HL-2A  HL-2A tokamak  Diagnostic development  Confinement improvement and transport  Energetic physics and MHD activity  Turbulence and zonal flows  Summary Outline

Longwen Yan, Experimental Progress on HL-2A, 6-8 Jan. 2014, Tsinghua University, Beijing 18/29 HL-2A Basis of Energetic Physics Beta-induced Alfven eigenmode (e- BAE) by energetic electrons was identified for the first time Multiple BAE modes are investigated Ion and electron fishbones were confirmed The frequency jump of e-fishbone was found uring ECRH. Long-lived runaway electron beam was observed during major disruptions (Zhang Y.P., PoP 19 (2012) ) The fast ion slowing-down time is in agreement with classical theoretical prediction (Zhang Y.P., PoP 19 (2012) ) Chen W., NF 49 (2009) Chen W., NF 50 (2010) Chen W., PRL 105 (2010)18500 Chen W., NF 51 (2011)

Longwen Yan, Experimental Progress on HL-2A, 6-8 Jan. 2014, Tsinghua University, Beijing 19/29 HL-2A Beta-induced Alfvén acoustic eigenmode BAAE with f = kHz identified by frequency up-chirping, consistent with the solution for Alfvén-acoustic continuum A clear spectrum splitting is first observed on BAAE Shot I p = 170 kA B t = 1.4T, q a  4.0, T e  1.0 keV T i  0.8 keV P NBI =0.6 MW Alfvén-acoustic mode Tearing mode Splitting Liu Yi, et al 2012, NF

Longwen Yan, Experimental Progress on HL-2A, 6-8 Jan. 2014, Tsinghua University, Beijing 20/29 HL-2A Frequency jump of e-fishbone mode Ip= kA n e =0.3~0.7×10 19 m -3 B T = T ECRH deposited inside q=1 surface Both low and high frequency branches are observed The high frequency branch could be observed only if P ECRH > 0.8 MW Frequency jump gap increases with the ECRH power Low & high frequency modes are m/n = 1/1 and 2/2 Electron fishbone frequency jump was observed in the low density ECRH plasma, where the trapped particles are dominant. Yu L. M., et al NF53,

Longwen Yan, Experimental Progress on HL-2A, 6-8 Jan. 2014, Tsinghua University, Beijing 21/29 HL-2A Low-frequency multimode coexistance Low frequency multiple Alfven modes coexist during high power ECRH. Mode frequencies decrease with n e and slightly increase with T e, finally overlap with each other. I p = kAB t = T n e 0.6 MW m/n = 4/2, 5/2, 3/1, 6/2, 4/1 Ding X. T. et al 2013 NF

Longwen Yan, Experimental Progress on HL-2A, 6-8 Jan. 2014, Tsinghua University, Beijing 22/29 HL-2A Long lived mode & its control LLM suppressed by ECRH or SMBI LLM observed during NBI with weakly reversed or broad low magnetic shear LLM degrades plasma confinement and enhances fast ion loss LLM oscillation in LFS is stronger than that in HFS Deng W. et al. 2014, NF

Longwen Yan, Experimental Progress on HL-2A, 6-8 Jan. 2014, Tsinghua University, Beijing 23/29 HL-2A  HL-2A tokamak  Diagnostic development  Confinement improvement and transport  Energetic physics and MHD activity  Turbulence and zonal flows  Summary Outline

Longwen Yan, Experimental Progress on HL-2A, 6-8 Jan. 2014, Tsinghua University, Beijing 24/29 HL-2A Basis of edge turbulence and ZFs The toroidal symmetries of GAM and LFZF were confirmed on HL- 2A for the first time Turbulence nonlinear energy transfer was identified for the first time Two types of LCO were founded Three dimensional structure of filamentary plasma was studied Zhao K.J., PRL 96 (2006) Yan L.W., NF 47 (2007) 1673 Zhao K.J., PoP 14 (2007) Lan T., PoP 15 (2008) Zhao K.J., NF 49 (2009) Cheng J., NF 49 (2009) Liu A.D., PRL103 (2009) Zhao K.J., PPCF 52 (2010)124008

Longwen Yan, Experimental Progress on HL-2A, 6-8 Jan. 2014, Tsinghua University, Beijing 25/29 HL-2A Nonlinear energy transfer Turbulent kinetic energy was transferred into LFZFs and GAMs the energy transferred into LFZFs increases with heating power Turbulence drives low frequency sheared flows Nonlinear energy transfer rate Xu M. et al PRL 108,

Longwen Yan, Experimental Progress on HL-2A, 6-8 Jan. 2014, Tsinghua University, Beijing 26/29 HL-2A Two types of I-phase trajectory Trajectories of the system in phase space of normalized radial electric field E r and RMS of the density envelope ( kHz) measured at Δr = −5 mm for discharge with L-I-H transition (a) and L-I-L transition (b). Cheng J. et al PRL

Longwen Yan, Experimental Progress on HL-2A, 6-8 Jan. 2014, Tsinghua University, Beijing 27/29 HL-2A Eddy amplitude increases firstly, it is stretched and split into two islands by strong E×B flow, finally plasma filaments are ejected into SOL The flow shearing time at filamentary birth position is identified to be close to the filament generation time (~4  s ) Filament generation near the inner LCFS -8  s -6  s-4  s -2  s 0s0s 2s2s I p = kA B t = T n e = ×10 13 cm -3 q 95 = r/a = Dependent on the significant parallel correlation Spatiotemporal evolution of E×B shearing rate Cheng J. et al 2013 NF53,

Longwen Yan, Experimental Progress on HL-2A, 6-8 Jan. 2014, Tsinghua University, Beijing 28/29 HL-2A Summary MSE, FILD, and MWR with high resolutions succeeded ELM frequency rises to a factor of but its amplitude drops 38% by using SMBI/CJI mitigation. CJI is more efficient than SMBI for the ELM mitigation L-I-H transition can be induced by sawtooth crashes ELM-free H-mode observed with m/n=3/1 EHO mode of 5-8 kHz The SMBI fuelling efficiency is enhanced by strong convection The strong decrease of the CV intensity compared with CIV in ECRH needs a outer convection velocity of 7 m/s Frequency jump of e-fishbone and LF multimode coexistence Long lived modes have been controlled by ECRH and SMBI Turbulent energy transferred into ZFs ＆ GAM by nonlinear process Normalized E r ~ 1 is critical to trigger L-I-H transition Plasma filament just generated at the inner LCFS

Longwen Yan, Experimental Progress on HL-2A, 6-8 Jan. 2014, Tsinghua University, Beijing 29/29 HL-2A Thank you for your attention !