Temperature model identification on FTU liquid lithium limiter

In this paper, the model identification of the tem- perature over the surface of the limiter adopted in the Frascati Tokamak Upgrade (FTU) is presented. Tokamaks are considered as the most interesting facilities to study self-sustained nuclear fusion reactions. Recently, a Liquid Lithium Limiter (LLL) has been introduced in the FTU with the aim of reducing impurities in the plasma. However, the performance of the LLL are maximized when temperature over its surface is uniformly distributed. In this paper, we face the problem of modeling the thermal behavior of the limiter surface following two different data- driven approaches: a linear autoregressive model, and a nonlinear autoregressive model. A comparison among the two models will be given, showing also which physical quantities are relevant to the specific modeling problem