Theoretical assessment of the OTDR detector noise on plasma current measurement in tokamaks

Ratislav Motuz, Willem Leysen, Philippe Moreau, Andrei Goussarov, Petr Drexler, Marc Wuilpart

    Research outputpeer-review


    In this paper, we propose a theoretical study dedicated to the assessment of plasma current measurement in magnetic confinement fusion reactors using a polarization optical time-domain reflectometer (POTDR) setup with a low-birefringence fiber used as the sensing fiber. We consider the general case of a non-uniform magnetic-field distribution along the sensing fiber. The numerical simulations, based on Jones formalism taking into account the OTDR noise, provide the measurement error as a function of the plasma current. The measurement performance is evaluated for an ITER-relevant sensor configuration. We demonstrate that a signal-to-noise ratio of 6 dB, achievable in modern POTDRs, allows us to comply with the ITER requirements for plasma currents from 0 to 1 MA, while for the 1 to 20 MA range, the level is relaxed to 4 dB.
    Original languageEnglish
    Pages (from-to)2795-2802
    Number of pages8
    JournalApplied Optics
    Issue number11
    StatePublished - 10 Apr 2019

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