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(EX/C4-2Rb) Experiments on Electron Temperature Profile Resilience in FTU Tokamak with Continuous and Modulated ECRH

S. Cirant¹⁾, E. Lazzaro¹⁾, A. Bruschi¹⁾, M. De Benedetti²⁾, F. De Luca³⁾, B. Esposito²⁾, F. Gandini¹⁾, G. Granucci¹⁾, A. Jacchia¹⁾, E. Minardi¹⁾, S. Nowak¹⁾, C. Sozzi¹⁾, O. Tudisco²⁾, ECRH Group¹⁾, FTU Team^2)
 
1) Istituto di Fisica del Plasma - CNR, Milano, Italy
²⁾ Centro Ricerche Energia, Associazione EURATOM/ENEA/CNR sulla Fusione, Frascati, Rome, Italy
³⁾ I.N.F.M. and Dipartimento di Fisica, Università degli Studi di Milano, Milano Italy

Abstract.  Experiments performed on FTU tokamak, aiming at validation of physics-based transport models of the electron temperature profile resilience, are presented. ECRH is used to probe transport features, both in steady-state and in response to perturbations, while ECCD and LHCD are used for current density profile shaping. Observed confinement behaviour shows agreement with a critical temperature gradient length modelling. Central, low gradient plasma is characterized by low stiffness and low electron thermal diffusivity. Strong stiffness and high conduction are found in the confinement region. Resilience is experimentally characterized by an index of the resistance of the profile to adapt its shape to localized ECRH, while the diffusivity and its low-high transition are measured both by power balance and heat pulse propagation analysis. A particular attention is given to the investigation of the transition layer between low-high diffusivity and low-high stiffness regions. A dependence of LTc on magnetic shear, similar to what found in Tore Supra, and consistent with ETG based anomalous transport, is found.

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