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Density profiles of H-mode plasmas in JT-60U

Density profiles of H-mode plasmas in JT-60U. H. Takenaga, H. Urano, N. Oyama JAERI, Naka Acknowledgment : S. Watanabe (Kyoto University) 8th Meeting of the ITPA Confinement Database & Modeling Topical Group 18-21 April, 2005 Kyoto University , Kyoto, Japan. JT-60U. Outline. Introduction

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Density profiles of H-mode plasmas in JT-60U

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  1. Density profiles of H-mode plasmas in JT-60U H. Takenaga, H. Urano, N. Oyama JAERI, Naka Acknowledgment : S. Watanabe (Kyoto University) 8th Meeting of the ITPA Confinement Database & Modeling Topical Group 18-21 April, 2005 Kyoto University, Kyoto, Japan

  2. JT-60U Outline • Introduction • Density profile in NB heated H-mode plasmas • High d configuration • Low d configuration • Density profile in ECH H-mode plasmas • Summary

  3. JT-60U Introduction Density profile in a fusion reactor ? • Flat profile • No or small impurity accumulation • Low fusion output Peaked profile • High fusion output • Impurity accumulation ? Low central fueling Anomalous inward pinch What is the mechanism determining the density profile ? • ASDEX-U, JET : density peaking factor increased with decreasing the effective collisionality (neff). • neff=nei/wDe : wDe is the curvature drift frequency C. Angioni et al., Phys. Plasmas 10 (2003) 3225. H. Weisen et al., 20th IAEA Fusion Energy Conference (2004, Vilamoura) EX/P6-31.

  4. JT-60U NB heated H-mode database Ip=1.0 MA, BT=2-2.1 T, Pabs=8-10 MW, ne/nGW=0.3-0.7 High d : d=0.4-0.5, Low d : d=0.2-0.3 H89PL is larger in high d than in low d for ne/nGW<0.6. Highd Low d

  5. JT-60U Density peaking factor tends to increase with decreasing the effective collisionality. • But, data are scattered in low neff region. • No clear dependence on d. • Dependence of density peaking factor on neff is similar to that in ASDEX-U and JET. neff~0.1RZeffne/Te2

  6. JT-60U Density profile peaking accompanies with temperature profile peaking. • Density peaking seems to be correlated with confinement improvement. • Data and fitting qualities should be checked in future work. E041544, 3.585s H89PL=1.5, ne/nGW=0.43 E037843, 8.9s H89PL=1.9, ne/nGW=0.40 ne (1019 m-3) Te (keV) Ti (keV) E037843, 8.9s E041544, 3.585s

  7. JT-60U Density peaking seems to be correlated with ion temperature peaking. • Correlation between density peaking and electron temperature peaking is not clear. neff<0.4 neff<0.4

  8. JT-60U ECH H-mode • Type I ELMy H-mode plasma with 2nd harmonic X-mode ECH without central fueling. • H89PL=1.4 at ne/nGW~0.6 with PEC~3 MW. L-mode H-mode E041498 Ip=1.1 MA, BT=2.0 T Center EC Wave deposition ne (1019 m-3) Te (keV) H-mode L-mode

  9. JT-60U ECH H-mode has a similar density peaking factor to that in NB H-mode. • Absence of central fueling does not significantly affect the density profile. ECH H-mode ECH H-mode

  10. JT-60U Summary • Density profiles are investigated in NB and ECW heated H-mode plasmas. • The density peaking factor tends to increase with decreasing the effective collisionality, but data are scattered in low collisionality region. • One of the reasons for scattering of the data could be different confinement. The density peaking factor seems to be correlated with the ion temperature peaking factor. Data and fitting qualities should be checked in future work. • ECH H-mode has a similar density peaking factor to that in NB heated H-mode, indicating small effects of the central fueling.

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