The Hangzhou International Stellarator Workshop (HISW2018)-会议-浙江大学聚变理论与模拟中心.pdf 
The Hangzhou International Stellarator Workshop (HISW2018)-会议-浙江大学聚变理论与模拟中心.pdf
Hangzhou International Stellarator Workshop March 26th-28th, 2018, Zhejiang University, Hangzhou, China Recent Results from The Heliotron J Experiment Presented by K. Nagasaki Institute of Advanced Energy, Kyoto University The Heliotron J Group and Collaborators T. Mizuuchi, K. Nagasaki, H. Okada, T. Minami, S. Kado, S. Kobayashi, S. Yamamoto, S. Ohshima, S. Konoshima, T. Senju, K. Yaguchi, M. Shibano, K. Toshi, K. Sakamoto, K. Nakagai, T. Takahashi (IAE, Kyoto University) Y. Kishimoto, Y. Nakamura, A. Ishizawa, K. Imadera (GSES, Kyoto Univ.) S. Murakami, T. Shikama (Graduate School of Engineering, Kyoto Univ.) Y. Takeiri, M. Osakabe, K. Y. Watanabe, S. Okamura, M. Yokoyama, K. Nagaoka, Y. Suzuki, Y. Narushima, S. Nishimura, S. Sakakibara, K. Tanaka, H. Takahashi, G. Motojima, Y. Yoshimura, H. Igami, K. Ogawa, K. Mukai, T. Oishi, N. Tamura (National Institute for Fusion Science) N. Nishino (Hiroshima Univ.), T. Fukuda (Osaka Univ.), Y. Nakashima (Univ. Tsukuba) , S. Kitajima (Tohoku Univ.) , N. Kenmochi (U. Tokyo) D. Anderson, K. Likin, C. Deng (Univ. Wisconsin, USA) N. B. Marushchenko, G. Weir (IPP, Germany)) E. Ascasibar, A. Cappa, T. Estrada, F. Castejon (CIEMAT. Spain) B. Blackwell (ANU, Australia) D. Yu, L. Zang (SWIP, China), J. Zhu (Zhejiang Univ.) B. Liu (Southwest Jiaotong Univ., China) Outline 1. History of Heliotron Research and Heliotron J 2. Magnetic configuration control ̶ ̶ ̶ Neoclassical transport Anomalous transport Energetic particle confinement 3. Recent experimental results ̶ High-density H-mode triggered by high intense gas puffing ̶ Isotope effect on edge turbulence ̶ Electron ITB ̶ Suppression of energetic-particle-driven MHD modes by ECH/ECCD 4. Summary Outline 1. History of Heliotron Research and Heliotron J 2. Magnetic configuration control ̶ ̶ ̶ Neoclassical transport Anomalous transport Energetic particle confinement 3. Recent experimental results ̶ High-density H-mode triggered by high intense gas puffing ̶ Isotope effect on edge turbulence ̶ Electron ITB ̶ Suppression of energetic-particle-driven MHD modes by ECH/ECCD 4. Summary Heliotron Fusion Research in Kyoto University 1958 1966 超高温プラズマ “Cradle” 研究施設（工学部） Project Helicon PPL, Dep. Eng. Kyoto Univ. Kyoto Univ. 1959 1996 1976 ヘリオトロン 核融合研究センター PPL, Kyoto Univ. エネルギー理工学研究所 IAE, Kyoto Univ. エネルギー科学研究科 GSE, Kyoto Univ. 1980 1960 1965 1970 1975 Heliotron A Heliotron B R=0.47m a=0.075m B=0.6T Heliotron C Heliotron D R=1.085m a=0.1m B=0.3T Heliotron DM R=0.45m a=0.04m B=1T Advanced Heliotron E Helical Concept R=2.2m a=0.2m B=2T 2000 1998 LHD (NIFS) Heliotron J Helical-Axis Heliotron Configuration M. Wakatani, Y. Nakamura et al., Nucl. Fusion 40 (1999) 569 Keywords： High-level compatibility between good particle confinement & MHD stability Currentless steady state Potential for built-in divertor Compact & high-b Simple helical coil system 1. Omnigeneity for drift optimization and magnetic well for MHD stability are combined with a helical magnetic axis High-b Control of neoclassical and turbulent transport 2. Bumpy component as the third knob of configuration control s-optimization Control of BS current Er effect Heliotron J Device Specification Single helical coil (l=1), two kinds of toroidal coil and three pairs of poloidal coil Flexibility of magnetic configuration R=1.2 m, < 0.2 m Bt < 1.5 T, 0.4 < i/2p < 0.65 Nf = 4, helical-axis Heliotron Heating systems ECH: P < 0.4 MW, f = 70 GHz NBI: P < 1.6 MW, E < 30 keV (H) [co and counter injection] ICRF: P < 0.8 MW Achieved plasma parameters ଶ ିଷ ୣ Te(0) <3 keV Ti < 0.4keV Characteristics of Heliotron J Configuration The straight structure is designed where quasi-omgeneity is formed Corner section (f=45) Straight section (f=0) Straight section (f=45) Iota Corner section (f=45) well depth The magnetic field strength is flat in the straight section, making the magnetic field gradient gentle. The B contour shape is tokamak-like at corner section Role of Bumpiness • Bumpiness provides control of Bmin contour for deeply trapped particles • Inward shift of magnetic axis is not necessary for optimization of neoclassical transport Fourier Spectra of B • Field configuration of Heliotron J is mainly composed of toroidicity, helicity and bumpiness • Helical coil winding law p M M f sin f L L • The negative produces magnetic well in the whole plasma region Reduction of neoclassical ripple transport Control of bootstrap current MHD stabilization and good energetic particle confinement Three Bumpiness Configurations Toroidicity Bumpiness (eb=B04/B00) can be changed with toroidicity and helicity fixed ・ eb = 0.15 (high bumpiness) ・ eb = 0.06 (medium bumpiness, STD) ・ eb = 0.01 (low bumpiness) at r~2/3a Helicity Bumpiness Outline 1. History of Heliotron Research and Heliotron J 2. Magnetic configuration control ̶ ̶ ̶ Neoclassical transport Anomalous transport Energetic particle confinement 3. Recent experimental results ̶ High-density H-mode triggered by high intense gas puffing ̶ Isotope effect on edge turbulence ̶ Electron ITB ̶ Suppression of energetic-particle-driven MHD modes by ECH/ECCD 4. Summary Experimental BS current Agrees with Neoclassical SPBSC Code Results Experimental bootstrap current agrees with neoclassical prediction within a factor of 2 at ne = 0.4-1.0 1019 m-3 (off-axis deposition) n = 0.4x1019 m-3 e ne = 1.0x1019 m-3 BS current is dominant at this resonance condition Three kind of pressure profiles are assumed G. Motojima, Fus. Sci. Tech (2007) Role of Trapped Electrons on ECCD • The experimental results quantitatively agree with a theoretical calculation using the TRAVIS code which includes parallel momentum conservation High bumpiness h=0.82 PECH=260kW 3 IEC (exp) 0.95 e b = 0.06) 0.99 ( e b = 0.05) 1.06 ( e b = 0.01) 1.3 1.2 ECH injection port 1.1 1.0 -45 1 4 IEC (theory) 3 -3 -15 0 15 30 45 Low bumpiness h=1.06 PECH=260kW 0/=0.499 19 -3 ne~0.5x10 m 2 1 2 1 0 0 0 -30 Toroidal Angle f (deg) ne~0.5x10 m -3 IEC (kA) IEC (kA) 0.89 ( e b = 0.13) IEC (exp) 0/=0.478 19 ne~0.5x10 m 2 h=0.95 PECH=260kW 0.82 ( e b = 0.15) 1.4 Medium bumpiness 3 IEC (theory) 0/=0.490 19 4 0.78 ( e b = 0.17) 1.5 IEC (kA) 4 B str/B cor 1.6 |B| (T) • Experiments on scanning magnetic field configuration in Heliotron J show importance of trapped electrons for ECCD 1.7 IEC (exp) IEC (theory) -1 0.0 0.2 0.4 N|| 0.6 -1 0.0 0.2 0.4 N|| 0.6 -1 0.0 0.2 0.4 0.6 N|| K. Nagasaki, Nucl. Fusion (2011) Effect of Bumpiness on Parallel Plasma Flow Lee, PPCF (2013) Nishioka, PoP (2016) The measured C6+ parallel flow is consistent with the neoclassical prediction with the SugamaNishimura method including the edge spontaneous flow Medium bumpiness (STD) High bumpiness Global Confinement Depends on Bumpiness Component • Good global energy confinement is obtained at the magnetic configuration with medium bumpiness (ECH) and high bumpiness (NBI) Power scan experiments Density scan experiments T. Mizuuchi, FST 50 (2006) 352 S. Kobayashi , FEC (2008) EX/P5-13 GKV Code Results Show That Zonal Flow in High Bumpiness Suppresses Turbulence Transport • GKV code is applied to HJ NBI plasmas. ITG mode is unstable Elongated mode structure in B direction due to weak shear Large amplitude of ZF is expected Growth-rate in high eb case is smaller than standard one Nonlinear calculation shows same tendency due to stronger |B| at bad-curvature region Consistent to the experimental result Config standard High eb g(vTi/R0) 0.4 0.26 ci(vTir2Ti/R0) 5.9 4.2 ce(vTir2Ti/R0) 2.4 1.7 Electrostatic potential profile of the ITG mode A. Ishizawa et al 2017 Nucl. Fusion 57 066010 High Bumpiness Is Favorable for Energetic Minority Proton Confinement and Bulk Heating Bulk Heating vs. Bumpiness • ICRF pulse of 23.2 MHz or 19 MHz with 250-290kW was injected into an ECH target plasma where Ti(0) = 0.2 keV, Te(0) = 0.8 keV and ne = 0.4 x 1019 m-3 0.25 B04/B 00 = 0.15 T i (keV) 0.20 • High energy ion-flux up to 34 keV is observed at the pitch angle of 120 deg only in the high bumpy case 0.15 0.10 B04/B 00 = 0.01 0.05 • The bulk ion heating efficiency in the high bumpiness is highest among three configurations B04/B 00 = 0.06 0.00 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 PICRF (MW) 125 deg 121 deg 117 deg 113 deg 108 deg 104 Pitch Angle 103 102 101 125 deg 121 deg 118 deg 112 deg 108 deg 105 fH(E) (arb.) fH(E) (arb.) 105 Medium Bumpiness 19 MHz 127 deg 106 104 5 10 15 20 25 Energy (keV) 30 35 101 104 111 deg Pitch Angle 103 102 102 0 123 deg 120 deg 118 deg 114 deg 105 Pitch Angle 103 High Bumpiness 23.2 Mhz 128 deg 106 fH(E) (arb.) Low Bumpiness 19 MHz 128 deg 106 0 5 10 15 20 25 Energy (keV) 30 35 101 0 5 10 15 20 25 Energy (keV) 30 35 Outline 1. History of Heliotron Research and Heliotron J 2. Magnetic configuration control ̶ ̶ ̶ Neoclassical transport Anomalous transport Energetic particle confinement 3. Recent experimental results ̶ High-density H-mode triggered by high intense gas puffing ̶ Isotope effect on edge turbulence ̶ Electron ITB ̶ Suppression of energetic-particle-driven MHD modes by ECH/ECCD 4. Summary H-Mode Transition Triggered by High-Intensity Gas Puffing in NBI Plasmas Low et config |B|=1.3T, PNBI=1MW #60553(H) 0 -3 I (kA) t e #60553 -4 20 0 0 -1 0.4 210ms -0.5 0 0.5 1 Te H/D e 0.15 (A.U.) 0 200 ~ 40 BES(r/a=0.9) -2 Log10 (IBE)2 f (kHz) 0 ne 235ms e 5 (x1019m-3) I 245ms 5 T (keV) W #60514(L) n FIR (kJ) DIA 19 DIA ,I t W #60553-60559 n (x10 m ) 6 210 220 230 time (ms) 240 250 0 -1 -0.5 0 r/a 0.5 A short-pulsed high intensity gas puffing (HIGP) was applied from inboard side. H-mode transition has been observed with formation of steep density gradient at peripheral. Before transition, an n = 2 bursting mode (4-30kHz) and low-f fluctuation (<3kHz), which causes particle exhaust, have been observed. 1 Kobayashi, IAEA FEC 2016 Relation between Bursting Mode and H-mode Transition 0.4 #60553, Low et config. 0.2 0.3237 238 Mirnov 239 240 0 303.3deg 0 -1 0.85 -80 -40 237 IBEr/a=0.98 - IBEr/a=0.94 238 IBEr/a=0.94 - IBEr/a=0.88 Low-pass filtered (<3kHz) BES 239 240 time (ms) 241 242 -4 -70 -60 -50 e 0.95 1 19 Bursting frequency (0.8-3kHz) BES Filtered dn /dr (x10 m ) r/a 242 f 241 =33.3deg TOR -0.3 IBE/r(A.U.) • Reduction in the particle exhaust at transition may trigger formation of the steep density gradient in the peripheral region ~ IBE (A.U.) dB/dt (A.U.) IH/D(A.U.) • A bursting n=2 mode with f=5-30kHz has been observed in density and magnetic fluctuations before L-H transition -40 0 #60520-#61868 HIGP width 10-15ms P =1MW NB noise level w/ H-mode transition -3 0.8-3kHz 5 10 I / BE BE Kobayashi, IAEA FEC 2016 Isotope Effect and Its Configuration Dependence of Zonal Flow Low bumpiness [a.u.] <4kHz 0.1 0.05 H 0 0 0.2 0.4 0.6 Coherence 0.8 Larger amplitude Stronger correlation on D plasmas 5 to 3 0.1 <4kHz D 1 Fluc. Amplitude [a.u.] Standard Fluc. Amplitude <4kHz Coherence Coherence A hypothesis/ ZFs contribute to isotope effect？ H 0.05 D 0 0 0.2 0.4 0.6 0.8 1 Coherence Smaller amplitude Weaker correlation on D plasmas Isotope effect on long range correlation (ZF) were Opposite dependence of isotope effect, weaker investigated in Tokamaks correlation and amplitude of ZF on D plasma, is (TEXTOR, ISTTOK) and helical observed in low bumpiness configuration. devices(TJ-II, Heliotron J). →Configuration optimization might be necessary from the viewpoint of turbulence & isotope effect. S. Ohshima, ISHW2017, Invited Talk Expansion of Enhanced Confinement Region in Electron ITB During Plasma Current Ramp-up ECH Conditions Heating position：magnetic axis Injection power: 270 kW absorption rate(X-mode, single path): ~90% The rapid increase of the Te at r/a~0.1 is observed at the plasma current ~0.6 kA. The eITB foot points moves to the outer region as the current increase. e-ITB Foot Point Moves As The n/m=4/7 Rational Surface Appears and Shifts Outward Rotational transform profiles after the formation of n/m=4/7 rational surface eITB foot point after the formation of n/m=4/7 rational surface When the plasma current exceeds the threshold (Ip ∼ 0.9 kA), the ι(r/a)/2π exceeds 4/7 and the rational surface i/2π= 4/7 appears As the plasma current increases, the ι(r/a)/2π around r/a ∼ 0.2 increases, causing the movement of the position of rational surface. According to the movement of the rational surface, the eITB foot point moves to the outside region. Both Co and Counter ECCD Stabilize EPM and GAE in Heliotron J Ctr-ECCD (N||= -0.3) No ECCD (N||=0.0) 1.0 0.5 #46118 1.0 19 -3 ne (10 m ) 0.5 Ip (kA) 1 19 1.0 -3 dB/dt (a.u.) 0.5 Ip (kA) 0 -1 dB/dt (a.u.) 0.5 0.0 -0.5 -0.5 -0.5 0.0 200 250 TIme (msec) NBI 0.2 70GHz ECH (N||=0.0) 0.5 70GHz ECH (N||=0.3) 0.0 300 dB/dt (a.u.) 1.0 0.4 200 250 NBI(BL1) 70GHz ECH (N||=0.4) 0.0 300 200 TIme (msec) 500 Frequency (kHz) 0.2 2012.07.12 -3 Ip (kA) 1 0.0 NBI 19 0.0 2 0.0 0.4 5to3 (HV+86TA+60TB+98AV+19IV-15) 0.5 -1 -1 #48104 ne (10 m ) ne (10 m ) 0 0 0.5 2011.12.21 #46128 0.0 2 0.0 2 1 Co-ECCD (N||= +0.4) 250 TIme (msec) #48104, 5to3 configuration 300 N||=0.4 400 300 200 100 0 150 200 250 Time (msec) 300 Nagasaki, Nucl. Fusion (2013) Yamamoto, Nucl. Fusion (2017) Stabilization Effect Depends on Magnetic Shear Intensity • EC-driven current enhances magnetic shear (s ~ 0 in vacuum) • Amplitude of EPMs is obviously suppressed by increasing Ip regardless of its sign ECH-only phase 0.02 #46107-46132 iota=0.525 B=1.25T ECH 0.3MW NBI 0.6+0.8MW 0.3 -5 0.04 #48085-48115 5to3 config B=1.21T (HV+86%) co-ECCD 0.26 MW NBI BL1 0.5MW brms/Bt (x10 ) -5 brms/Bt (x10 ) 0.06 0.2 Stabilized 0.1 ECH-only phase 0.00 -0.4 -0.3 -0.2 -0.1 0.0 r/i(di/dr) at r/a=0.6 0.1 0.0 0.0 0.1 0.2 r/i(di/dr) at r/a=0.6 • EPMs suffer from strong continuum damping whose rate is proportional to magnetic shear • Increase in absolute magnetic shear leads to suppression of EPMs A Low-Frequency Alfvén Eigenmode (LF-AE) Is Observed in Co-NBI Plasmas • LF-AE is steadily observed in NBI heated, co-current flowing plasmas in standard configuration. • Real frequency linearly depends on . • Real frequency is near the boundary of BAE gap. • Nonlinear interaction exists among bands of LF-AE and a very low frequency (<10kHz) m=0,n=0 mode. TAE EPM BAE DATA rho0.71 f* = 41 kHz Near-Future Plans We will carry out next experimental campaign from July, 2018 • Understanding of MHD and Turbulence ̶ Isotope effect (H/D ratio control) ̶ Turbulence measurement with fast CXRS, reflectometer, CECE, Langmuir probes, fast digitizer oscilloscope • Optimization of particle fueling and operation scenario ̶ HIGP, SMBI, pellet injection ̶ Resonant magnetic perturbation coils • Control and measurement of plasma profiles and flow ̶ Iota (q) control for e-ITB ̶ Toroidal and poloidal flow measurement with CXRS ̶ Multi-pass Nd:YAG TS system and multi-channel 320GHz FIR system • Energetic particles and related MHD instabilities ̶ Scintillator type lost ion probe, Si FNA, Fast camera • Impurity transport ̶ Laser blow-off method Summary • The 3D magnetic configuration scan in Heliotron J has demonstrated - The parallel transport such as BS and EC current and toroidal rotation agrees with neoclassical theory - The bumpiness affects the global energy confinement and the energetic particles • Recent experimental results show - The high-density H-mode triggered by HIGP is closely related to a bursting mode, forming steep density gradient in the peripheral region - Long range correlation is enhanced at D-dominant plasmas - Electron ITB formation is linked with a rational surface - AEs are effectively stabilized by ECH/ECCD • We have been carrying out the Heliotron J experiments for 18 years • We have started discussion about next generation machine