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Overview of Plasma Rotation with ICRH and / or LHCD in Tore Supra C. Fenzi-Bonizec

Overview of Plasma Rotation with ICRH and / or LHCD in Tore Supra C. Fenzi-Bonizec for the Tore Supra team Association Euratom-CEA sur la Fusion Contrôlée DSM/DRFC, CEA-Cadarache, 13108 S t Paul-lez-Durance Cedex, France. Background.

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Overview of Plasma Rotation with ICRH and / or LHCD in Tore Supra C. Fenzi-Bonizec

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  1. Overview of Plasma Rotation with ICRH and / or LHCD in Tore Supra C. Fenzi-Bonizec for the Tore Supra team Association Euratom-CEA sur la Fusion Contrôlée DSM/DRFC, CEA-Cadarache, 13108 St Paul-lez-Durance Cedex, France

  2. Background Plasma rotation can have beneficial effects on the performance of a tokamak plasma (MHD activity, confinement, …). Many experiments reported toroidal plasma rotation without momentum input (JET, C-MOD, Tore Supra, …): JET  ICRH (Eriksson et al. PPCF 39, 27 (1997)) C-MOD ICRH (Rice et al., NF 39 (1999)) Tore Supra ICRH & LH It is of great interest to identify the mechanisms underlying this plasma rotation: strong implication for ITER

  3. OUTLINE • Tore Supra experimental conditions • Rotation in various plasmas: OH / LHCD / ICRH • Summary and perspectives

  4. Experimental Conditions • L-mode plasma performed at Ip = 0.6MA – 1.4MA / 3.8T (magnetic field ripple up to 7%) • LHCD: PLH ≤ 4MW • ICRH (H-min) : PICRH ≤ 8MW, nH/ne= 3% -15%, 1H resonance layer @ low / high field side • VF and its direction for r/a ≤ 0.2, provided by X-ray spectrometer (heavy ion impurities) • VF profile provided by CXRS (CVI lines), typically covering 0 ≤r/a ≤0.65 but rotation direction still to be validated (uncertainties on reference line used)

  5. ×10 |VF|(km/s) #TS32536 Counter-current rotation in OH plasmas • Previous current reversal experiment: VF(0) ~ -20km/sct-current (X-ray) • Romannikov et al., NF Vol 40, No.3 (2000) …confirmed later on by CXRS measurements • Compatible with predictions of neoclassical theory including the effect of ripple trapped particles.

  6. #35595 Wdia (MJ) LH (1.9 MW) Te (keV) Ti (keV) DVF (km/s) Co-current Count-current Co-rotation with LHCD Qualitatively explained by fast electron ripple loss mechanism

  7. #23997 Wdia (MJ) 6 MW IC 1.5 MW LH Te (keV) Ti (keV) Co-current DVF (km/s) Counter-current Generally counter-rotation observed with ICRH 1.3 MA/ 6.5x1019m-3 Fast ion loss up to 20% Low fast elec. loss Could be explained by fast ion ripple loss. Simple model of the fast ion current loss gives VF ~ -20 km/s, close to the experimental results.

  8. # 33627 Wdia (MJ) Ti (eV) 3 MW 3.1MW 1 MW ICRH 2 MW 2.1MW Te (keV) 1MW Ti (keV) DVF (km/s) |VF|(m/s) Co-current 3.1MW 2.1MW Mag. axis 1MW But Co-rotation with ICRH also observed

  9. Role of H minority concentration in rotation direction with IRCH? TS #21044 TS #23967 high concentration: co-rotation Efficient bulk ion heating Enhanced confinement Ct-current low concentration: counter-rotation dominant electron heating Co-current 1H resonance layer located in the high field side for both plasmas Hoang et al., NF Vol. 40 No. 5 (2000) Eriksson et al., NF Vol. 41 No. 1 (2001)

  10. Co-rotation with ICRH scales with Wdia/Ip V (0)  Wdia / I p) similar behaviour in C-MOD Riceet al., NF 39, 1175 (1999) Assas et al. EPS2003 Wdia includes thermal / fast ion contributions Role of thermal / fast ions can not be separated Better thermal ion confinement or better fast ion confinement ?

  11. #TS36004 Wdia/Ip Ip (MA) ICRH (2MW) Wdia (MJ) Ti (keV) LH (2. MW) Te (keV) Ti (keV) DVF (km/s) DVF (km/s) Co-rotation Variation of rotation velocity is rather correlated with Ti, not with Wdia/Ip decreasing ne Better thermal ion confinement? Better RF power absorption?

  12. Co- rotation linearly increases with central ion pressure normalized to plasma current Fenzi et al. EPS 2004 suggests ion thermal effect

  13. #TS36073, 36076 |VF|(km/s) 1MA 1MA 0.6MA 0.6MA @ 14 s @ 14 s R [m] 1MA Wdia/Ip 0.6MA (Wdia-We)/Ip 1MA 0.6MA Strong co-rotation is rather correlated with good thermal ion confinement both discharges heated by ICRH (3MW)+ LH (1MW) higher Ip, higher Ti  less fast ion losses & better thermal ion confinement higher Ip &Ti  less fast ion losses better thermal ion confinement

  14. Summary • Counter rotation in OH plasmas possible mechanism: thermal ion ripple losses • Co-rotation in LH plasmas qualitativelyconsistent with fast electron ripple losses • Both co- and counter rotation in ICRH plasmas. - Counter-rotation consistent with fast ion losses (low nH, low power absorption); qualitative and quantitative agreement with calculations. • - Co-rotationcorrelated with good thermal ion confinement (or efficient ion heating): improved bulk ion heating + energy confinement improvement. Co-rotation at high minority concentration seems to be related to the transport properties rather than to fast particle effects.

  15. Perspectives • OH plasmas: possible thermal ion ripple loss effect will be clarified in up-coming experiment (varying ripple level) • LHCD plasmas: qualitative agreement with electron ripple losses, • on going modeling to reproduce quantitatively the experiments • Identify the origin of high edge VF(~30 km/s) • source in the SOL (L-mode), turbulence….? • Identify the origin of co-rotation in ICRH plasmas. • ‘thermal ripple force’?[Mikhailovskii, Plas. Phys. Rep.,1995) • Kuvshinov et al, Plas. Phys. Rep.,1995]

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