Heat Transport study by Modulated ECH on FTU tokamak
Abstract
On the FTU tokamak (major radius R=0.93 m, minor radius a=0.3 m), perturbative and steady state heat transport properties are investigated by means of modulated Electron Cyclotron Heating during current ramp-up. Perturbative transport experiments are compared to predictions of a empirical model based on the assumption of a threshold gradient length, LTc (1/LT=∇Te/Te), in the electron temperature Te below which electron thermal conductivity, χe, switches from low to high values. Plasma response to modulation is modeled assuming the electron conductivity as χPB=χ0+αTe3/2(1/LT-1/LTC)1/2 Te3/2 reflects the gyro-Bohm assumption, χ0 represents the heat transport for 1/LT < 1/LTC and the term (1/LT-1/LTc)1/2, which sets in for 1/LT>1/LTc, mimics an extra transport possibly due to Electron Temperature Gradient (ETG) modes.
Experiments are coherent with an electron heat transport which switches from low to high values when electron temperature gradient length reaches a threshold value 1/LTc. The threshold value 1/LTc, in agreement with ETG threshold predictions, is shown to be correlated with the magnetic shear s.- Publication:
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Electron Cyclotron Emission and Electron Cyclotron Heating
- Pub Date:
- February 2003
- DOI:
- 10.1142/9789812705082_0059
- Bibcode:
- 2003ecee.conf..389J