Long distance coupling between lower hybrid wave and plasma LHCD Group

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1 Long distance coupling between lower hybrid wave and plasma LHCD Group
Proposal for HT spring experiment HT-7 Long distance coupling between lower hybrid wave and plasma LHCD Group 高翔、远红外课题组、诊断(林士耀、徐国盛、张伟等)

2 OUTLINE HT-7  实验目的  实验背景 实验内容

3 MOTIVATION HT-7 To investigate the effect of distance between plasma and LHW antenna on wave-plasma coupling To investigate the effect of mismatch of plasma shape and LHW antenna on lower hybrid wave coupling To analyze the mechanism of gas and plasma behavior in gas puffing case NOTE THAT this experiment is a pre-performance for EAST

4 耦合条件 LH波的可耦合条件： 在天线发射面处应满足： wp≥w0 for f0=2.45GHz
HT-7 耦合条件 LH波的可耦合条件： 在天线发射面处应满足： wp≥w0 for f0=2.45GHz 要求： ne≥ ne,cut-off =7.44x1010cm-3 最佳耦合条件： ne≥n//2xne,cut-off =2.96x1011cm-3 (n//=2.0)

5 实验背景 HT-7

6 解决途径 HT-7 为了解决由于曲率半径不匹配而引起的多次反射、以及等离子体与天线端口的长距离耦合，在低杂波天线端口处充入可电离的气体，尽可能在天线端口处得到尽可能均匀的等离子体密度，且使其满足ne,grill, > ne,cut-off, 以提高波与等离子体的耦合效率。

7 实验准备 HT-7 喷气结构：安装在低杂波天线的周围。

8 HT-7 Wave-plasma couple with and without gas puffing

9 HT-7 wave-plasma couple with and without gas puffing

10 HT-7 Effect of gas flow rate on wave-plasma couple

11 HT-7 The plasma verical displacement was moved from dx=-10 to dx=10 shot by shot

12 HT-7 Little Effect of plasma vertical displace on coupling power

13 实验内容 实验条件 进一步核实实验过程中各道密度的变化情况，分析电离机理 Ip=80kA Ne=0.5 PLHW=300kW~500kW
HT-7 实验内容 进一步核实实验过程中各道密度的变化情况，分析电离机理 尝试改变垂直位移，观察波的耦合，并进行充气改善耦合 如果可能，改用D2进行实验，与CD4结果进行比较 实验条件 Ip=80kA Ne=0.5 PLHW=300kW~500kW 稳定重复的等离子体放电

14 Effect of IBW on LHW Power deposition
Proposal for HT spring experiment HT-7 Effect of IBW on LHW Power deposition LHCD and ICRF Group, 高翔，胡立群，赵君煜，万宝年

15 Outline  Motivation Obtained results on HT-7 tokamak
Synergetic mechanism of LHCD and IBW  Experiment arrangement

16 Motivation HT-7 To investigate the effect of IBW on LHW power deposition. To seek the condition of forming Electron ITB using LHW and IBW. To obtain high energy and high Beta plasma by means of LHCD&IBW.

17 Obtained results on HT-7 tokamak ---synergy of IBW and LHCD
f=27MHz, Bt=2.0T (Global IBW electron heating ), N//peak=2.35 B.N. Wan et al., Nucl. Fusion 43(2003)1279

18 An ITB seems visible in the region around r/a ~ 0.55
HT-7 An ITB seems visible in the region around r/a ~ 0.55 ASIPP

19 Obtained results on HT-7 tokamak ---electron heating by IBW
Global electron heating (left, f=27MHz, Bt=1.85T, r~3.4cm) and local electron heating (right, f=27MHz, Bt=2.0T, r~15.8cm) by IBW Revolution of oscillating IBW n// during the wave propagation along the trajectory IBW off-axis heating can modify the electron pressure profile B.N. Wan et al., Nucl. Fusion 43(2003)1279

20 IBW对低杂波功率沉积分布的影响 HT-7 HT-7tokamak不同纵场(A)、频率(MHz)时的2D共振层位置(cm) It(A)
HT-7tokamak不同纵场(A)、频率(MHz)时的2D共振层位置(cm) It(A) fIBW 3600 3800 4000 4200 30 -18 -12.5 -6.7 -0.9 27 -0.3 6.1 12.5 24 7.7 15 22.1 29.3

21 Synergetic mechanism of LHCD and IBW
HT-7 IBW can modify the distribution function of the electrons by extracting the thermal electrons from the bulk distribution and accelerate them to contribution to the LHCD  IBW can sustain driven current, dissipating its energy on the parallel velocity of the asymmetric electron tail

22 LHW + IBW (2007)

23 本轮实验系统改进之处 HT-7 LHW: 目前已经更换了不能正常工作的速调管
IBW：天线前面加了法拉第屏蔽，天线表面镀膜，有望减少杂质带来的密度升高

24 Experiment arrangement
HT-7 Experiment arrangement 实验方法： 改变纵场、IBW频率，移动IBW共振层的位置；改变低杂波波谱，优化低杂波功率沉积分布。 实验条件及参数: Ip~150~200kA, Ne~1.5~2.0 PIBW~400~500kW, PLHW~300~400kW fIBW=27MHz, 30MHz, （24 MHz）, It~3600,3800, 4000, 4200A 低杂波相位  (0)=-90, 0, 90, 150 拟分析不同条件下的Hard X-ray 分布、电子（离子）温度分布、密度分布、电流分布的变化（内感）、边界探针数据、MHD行为…… 希望需要配合的诊断： Te(r,t), Ti(r,t), Ne(r,t), HX(r,t), SX(r,t), W(t), li(t), Ha, AXUV(r,t), LP

25 　　　　谢　谢