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Lower Hybrid Wave Coupling and Current Drive Experiments in HT-7 Tokamak

HT-7. ASIPP. Lower Hybrid Wave Coupling and Current Drive Experiments in HT-7 Tokamak. Weici Shen Jiafang Shan Handong Xu Min Jiang HT-7 Team Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, 230031, P.R.China. HT-7. ASIPP. Outline.

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Lower Hybrid Wave Coupling and Current Drive Experiments in HT-7 Tokamak

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  1. HT-7 ASIPP Lower Hybrid Wave Coupling and Current Drive Experiments in HT-7 Tokamak Weici Shen Jiafang Shan Handong Xu Min Jiang HT-7 TeamInstitute of Plasma Physics, Chinese Academy of Sciences, Hefei, 230031, P.R.China

  2. HT-7 ASIPP Outline Experimental set-upLower hybrid wave coupling experimentLHCD improve confinementLHCD+IBW synergy experimentLong pulse discharge with LHCD

  3. HT-7 ASIPP 1.2MW/2.45GHzLHCD System

  4. HT-7 ASIPP Multijunction Grill Antenna

  5. HT-7 ASIPP Simulation of the lower hybrid wavepower deposition and drive currentIp=150kA, ne=1E1013cm-3, BT=1.8T, Te=1keV

  6. HT-7 ASIPP Reflection coefficient and Loop voltage versus spectrum and plasma parameters BT=1.6~2 T Ip=100~200kA ne=1~2.5×1013cm-3 The incident and reflected powers are determined from the performed by 12 bidirectional couplers. Lower power reflection coefficients and higher current drive efficiency are obtained when phase is between 0o and 90o. The mean reflection coefficient never exceeds 10%.

  7. HT-7 ASIPP HT-7 LHCD Typical DischargeIp=220kA, ne=1.5E13, Bt=1.8T, PLH=320kW

  8. HT-7 ASIPP LHCD Improve Confinement High performance phase Ip=150kA PLH=300kW BT=2T Ne 1.2~3 τp OH≈ 10ms τp LHCD≈ 45ms τE OH ≈ 4.9ms τELHCD≈13.5ms.

  9. HT-7 ASIPP Electron Heating and Internal Transport barrier formed during LHCD PLH=320kW, Te=500eV, rITB=0.37a

  10. HT-7 ASIPP Some diagnostic measurement results during LHCD Experiments hard X-ray intensity distribution Soft X-ray signals LHW modifies the edge Er Electron thermal diffusivity e

  11. HT-7 ASIPP Simulation of the LH Power Deposition and Plasma Current, q Profile The simulated result shows that off-axis LH power deposition makes a hollow current profile during theLHCD phase, which indicates that a negative magnetic shear,or at least, a low magnetic shear is formed.

  12. HT-7 ASIPP LHCD+IBW Synergy Experiment In high LH power combined with IBW heating scenario, a good heating effect has been observed (Te ~ 4keV). At this time, a good stationary wave coupling is maintained with reflection coefficient less than 3 %.

  13. HT-7 ASIPP LHCD+IBW Synergy Effect • A efficient for heating the bulk ion and electron of the plasma is observed. • A strong HXR emission is observed for combined LHW/IBW operation

  14. HT-7 ASIPP 64 second discharge with LHCD

  15. HT-7 ASIPP Conclusion • The new multijunction launcher, the reflect wave is very sensitive to the phase • between adjacent waveguide units.A good stationary coupling is maintained • when 2N//3.1 . The mean reflection coefficient never exceeds 10%. • The maximum LH wave power coupling to the plasma is above 600kW. • The high performance plasma enhanced confinement has been observed • with LHCD. • The plasma configuration with electron ITB has been obtained in LHCD by • optimizing plasma and wave parameters. The eITB is triggered at the • beginning of the LH wave inputting and sustained all LHCD phase. • The simulation results show that off-axis LH power deposition make a • hollow current profile. The current density profile modify by using LHCD. • A good heating and improve confinement effect has been achieved during • LHCD+IBW synergy experiment. • More than 1 minter long pulse plasma discharge has been achieved.

  16. HT-7 ASIPP Acknowledgements:The experiments are supported by HT-7 Operation, Diagnostic Group, Data Acquisition, and LHCD Group. The authors would like thank for their cooperation and kindly help. • References: • [1] Y. Peysson and the Tore Supra team, Nuclear Fusion, 41, 1703-1713 • (2001). • [2] S. Ide, et al., Proceedings of 16 th International Conference on Fusion • Energy, Montreal, 1996, (International Atomic Energy Agency, Vienna, • 1997) IAEA-CN-64/E-3. • [3] S. Ide, O. Naito, T. Oikawa, T. Fujita, T. Kondoh, M. Seki, K. Ushigusa • and JT-60 Team, Nuclear Fusion 40, 445 (2000). • [4] G.L. Kuang et al., Nuclear Fusion, 39(11), 1769 (1999). • [5] B.J. Ding et al., Phys. Plasmas, Vol. 9, No. 12, 4996 (2002). • [6] W.C. Shen et al., Plasma Science & Technology Vol.5, No.1 1633 (2003).

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