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研究生：章文扬导师：高翔，李亚东

磁剪切对微观湍流作用机制的实验研究

December 8, 2009 Hefei, China

ASIPPOutline

• Introduction– Motivation– Outstanding works

• Experiment on HT-7 during LHCD– 2008.3 experiment

• Open questions• References

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Electron Thermal Transport is Anomalous

• All operational modes of tokamaks have exhibited anomalous electron thermal transport.

• There is evidence that electron temperature profiles are stiff in tokamaks.

• Possible theoretical candidates include:– Trapped Electron Mode (and ITG with trapped electrons)– Electron Temperature Gradient Mode– Magnetic Flutter– Something other than Turbulence

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Reducing e in Burning Plasmas

• Various transport channels behave differently in forming ITBs.

• In most cases, Electron heat ITBs are formed by localized electron heating on RS plasmas [cf., JT-60U high triangularity, PS plasmas]

• The following stabilization mechanisms are likely to be ineffective in BP:– Density peaking for ITG, ETG,…– High Te/Ti for ETG (High Ti/Te for ITG )– NBI-driven Flow Shear (?)

• q - profile control (eg., RS) remains effective in reducing electron heat transport in Burning Plasmas:– Precession reversal of trapped particles– Suppression of ETG streamers– Stabilization of NTM

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TORE SUPRA:(a) The reversed current profile is the main factor leading to stabilization of the TEMs.(b) ETG overcomes the stabilizing effect of the negative magnetic shear on the ETG branch.

TORE SUPRA: Ip = 0.7 MA, BT = 3.9 T, ne(0) = 2.5 × 1019 m−3

C Fourment et al Plasma Phys. Control. Fusion 45

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NSTX:ITB with HHFW (negative magnetic shear)

E. Mazzucato Nucl. Fusion 49 (2009)

ASIPPOutline

• Introduction– Motivation– Outstanding works

• Experiment on HT-7 during LHCD– 2008.3 experiment

• Open questions• References

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HT-7 CO2 collective scattering system

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S i e imT q B

k

ks

s

12cm-1 18cm-1 20cm-1 24cm-1

Te:1.2keV

s :1.86mm

2.23 3.34 3.72 4.46

Te:0.9keV

s :1.61mm

1.93 2.89 3.22 3.84

Te:0.6keV

s :1.31mm

1.57 2.35 2.62 3.14

Te:0.45keV

s :1.14mm

1.38 2.05 2.28 2.72

Te:0.3keV

s :0.93mm

1.11 1.67 1.86 2.23

1.9tB T

ITER Physics Basis 2007

Chapter2 Plasma Confinement and transport E.J. Doyle et al

Drift wave turbulence scales

e ethee

ce e

m T

q B

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1.9tB T19 31.5 10en m Plasma current:120kA,150kA

2008 Experiment during LHCD LHW power:50kW---650kW

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Ohmic normalized fluctuation level

as a function of LHW power Plasma current:120kA Plasma current:150kA

•The stability of the mode in TEM and TEM/ETG range may be related to q profile.

ASIPPOutline

• Introduction– Motivation– Outstanding works

• Experiment on HT-7 during LHCD– 2008.3 experiment

• Open questions• References

ASIPPOpen questions

• Stiffness as a possible feature for characterising of ETGs?– Create condition where TEM stabilized while ETG should

be active.• Experimental conditions for e-ITBs

– Low density required?– Clear reversed magnetic shear required, not ExB shear

• True for pur e-ITBs , no trigger required ?• For e-ITBs in parallel with ion -ITBs also ? only condition ?

– Why e-ITBs do not form in parallel with ion-ITBs in some devices ?

• No direct experimental evidence of ETG dominating electron heat transport

ASIPPOutline

• Introduction– Motivation– Outstanding works

• Experiment on HT-7 during LHCD– 2008.3 experiment

• Open questions• References

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References

• [1] E J Doyle et al 2007 Nucl. Fusion 47 818• [2] Wolf R C et al 2001 Nucl. Fusion 41 1259• [3] Baranov Y F et al 2004 Plasma Phys. Control. Fusion 46 1181• [4] Jiquan Li and Y Kishimoto 2002 Plasma Phys. Control. Fusion 44 A479• [5] Rhodes T L et al 2006 Rev. Sci. Instrum. 77 10E 922• [6] Gusakov E Z et al 2006 Plasma Phys. Control. Fusion 48 A 371-6s• [7] Hennequin P et al 2004 Plasma Phys. Control. Fusion 46 B121• [8] Mazzucato E et al 2008 Phys. Rev. Lett. 101 075001• [9] Rhodes T L et al 2007 Plasma Phys. Control. Fusion 49 B183• [10] E Mazzucato 2009 Nucl. Fusion 49 055001• [11] Li Y D et al 2004 Plasma Sci. Technol. 6 2526• [12] Devynck P 1997 Plasma Phys. Control. Fusion 39 1355–1371• [13] Litaudon X et al 2001 Plasma Phys. Control. Fusion 43 677-693• [14] Gao X et al 2008 Plasma Phys. Control. Fusion 50 035006• [15] lin S Y et al 2006 Plasma science & Technology Vol 8 No.3• [16] C Fourment 2003 Plasma Phys. Control. Fusion 45 233–250• [17] Koide Y et al 1998 Plasma Phys.Control.Fusion 40 641

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Thanks for your attention!