PPPL-5243

Experimental and modeling uncertainties in the 
validation of Lower Hybrid Current Drive

Authors:  F. M. Poli
, P. T. Bonoli, M. Chilenski, R. Mumgaard, S. Shiraiwa, G. M. Wallace
, R. Andre, L. Delgado-Aparicio, S. Scott, J. R. Wilson, R.W. Harvey, Yu.V. Petrov
, 
M. Reinke, I. Faust, R. Granetz, J. Hughes, J. Rice, J. Walk

Abstract:  This work discusses sources of uncertainty in the validation of lower hybrid wave current drive simulations against experiments, by evolving self-consistently the magnetic equilibrium and the heating and current drive profi les, calculated with a combined toroidal ray tracing code and 3D Fokker-Planck solver. The simulations indicate a complex interplay of elements, where uncertainties in the input plasma parameters, in the models and in the transport solver combine and - in some cases - compensate each other. It is concluded that ray-tracing calculations should include a realistic representation of the density and temperature in the region between the con fined plasma and the antenna, which is especially important in regimes where the LH waves are weakly damped and undergo multiple reflections from the plasma boundary. It has been found that uncertainties in the processing of the diagnostic data have as large an eff ect on the calculations as the model approximations. It is shown that by comparing the evolution of the plasma parameters in self-consistent simulations with available data that inconsistencies can be identifi ed and limitations in the models or in the experimental data be assessed.
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Submitted to:  Plasma Physics & Controlled Fusion
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Download PPPL-5243 (pdf 3.4 MB 35 pp)
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