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Main result at low rotation

Experimental Study of the Ion Critical Gradient Length and Stiffness Level and the Impact of Rotational shear in the JET tokamak.

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Main result at low rotation

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  1. Experimental Study of the Ion Critical Gradient Length and Stiffness Level and the Impact of Rotational shear in the JET tokamak P.Mantica, D.Strintzi, T.Tala, C.Giroud, E.Joffrin, T.Johnson, H.Leggate, E.Lerche, T.Loarer, A.G.Peeters, A. Salmi, S.Sharapov, D.Van Eester, P.C. de Vries, L.Zabeo, K.-D.Zastrow and JET-EFDA contributors C.Petty, DIII-D H.Urano, JT60-U

  2. Main result at low rotation Gyro-Bohm normalization niTi5/2/R2B2 R/LTicrit~3.5 csi~7 Electrons in same shots less stiff cse~1 CGM

  3. For discussion GS2 qi linear with Dimits shift or quadratic without Dimits shift? Which value for ion stiffness in the range of experiments? Experiments typically lie near threshold, are simulations reliable in this region?

  4. The impact of rotation Adding up to 15 MW NBI--> increased torque and power Power increase taken into account via the gB normalization Higher R/LTi can be reached in presence of rotation! Similar linear threshold. Waltz rule =glin-0.6ExB accounts for a shift in threshold DR/LTi~1 ==> decrease in stiffness with rotation Main variation 1<t0<6 104rad/s. Cannot distinguish between rotation and its shear. Small variations in other parameters, R/LTe/R/LTi~ 1-2

  5. Attempt to compare hybrid shots from JET and DIII-D Main question: high H98 hybrid are easier to obtain in DIII-D than in JET, is it because of higher rotation in DIII-D? Near neoclassical at rt=0.33 At rt=0.6 it seems higher R/LTi at higher rotation for lower qi_norm. More points needed.

  6. Attempt to compare hybrid shots from JET and DIII-D Near neoclassical at rt=0.33 At rt=0.6 similar evidence as in JET observed. More points needed, also non-hybrid. It would be best to make an inter-machine comparison not using hybrid plasmas but MHD free L-modes or type III H modes like the ones of the JET ITG study. Possible coordinated experiments?

  7. Preliminary JT60-U Data taken from H.Urano 2008 NF using ruler! To be redone with proper data and larger numbers of shots. R/LTi in JT60-U is always the same irrespective of radius, normlaized heat flux and rotation. Very stiff plasma always with uniform threshold along radius?

  8. JET:Surprising preliminary evidence on dependence on q and s Ti R Small effect on R/LTi of significant changes in q profile. Cfr H.Urano, IAEA 2008

  9. Experiments on ion heat transport already scheduled at JET 2 sessions to study threshold dependence on q profile (dec 08) in plasmas with low rotation. L-mode, all RF in (3He)-D off-axis to locate threshold, change q by various pre-heat tricks. Then move RF on-axis with Ti modulation. 1 session to study effect of Te/Ti in plasmas with low rotation (dec 08) . L-mode, change RF central heating from mostly ions 3He~7% to mostly electrons H (D) ~4-5% Proposed for 2009 Try to separate effect of rotation from effect of its shear by using ripple

  10. For discussion Low rotation High rotation Ti profiles at the two extremes of the RF core heat flux scan at low and high rotation

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