Real-time determination of suprathermal electrons local emission profile from hard X-ray measurements in Tore Supra

The Tore Supra tokamak is well adapted to sustain long duration non-inductive discharges using the lower hybrid (LH) heating and current drive as the main power source. In these conditions the LH power deposition profile is strongly linked to the current density profile and can be deducted from the hard X-rays (HXRs) measurements which are produced by the suprathermal electrons (SE) generated by the absorption of the LH wave. The powerful HXR diagnostics that is operating in Tore Supra has been connected to the real-time (RT) data network. The availability of the HXR measurements in RT has allowed the development of an ad hoc algorithm for the RT computation of the SE local emission profile. Since the SE local emission profile is well representative of the LH power deposition profile, this can be controlled in feedback (and so the current density profile as well). This article illustrates the main issues of the code developed to compute the SE local emission profile and its RT connections, together with an explanation of the underlying physics and a description of the HXR diagnostics.