Preliminary demonstration on JET of an ITER neutron environment-compatible quadrupole mass-spectrometer

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Abstract

Strict limits recently imposed on neutron exposure to electronics for critical diagnostic systems on ITER, the fusion reactor demonstration facility under construction in the south of France, has led to the development of a quadrupole mass spectrometer with an exceptionally long cable. An 80 m cable exceeds the last state-of-the art limit of 15 m, imposed by the normally required proximity of the RF supply to the analyzer, and will allow locating the electronics in a neutron safe environment. This breakthrough, a joint development of ORNL with Hiden Analytical Ltd., was enabled by the use of an intermediate, RF-matching unit, free of silicon-based electronics, and using only vacuum tubes and an air-core transformer, rendering it resilient both to ionizing radiation and to fringing magnetic fields. After successful testing of the prototype unit, both at ORNL and Hiden's laboratories, the unit was installed on the JET tokamak, as part of a multi-sensor, divertor effluent gas analysis system, similar to one also under design for ITER. As such, the prototype will be tested both before and during the next nuclear (D-T) operation of JET, planned for mid-2021. In this paper, the prototype development, laboratory testing and first results from non-nuclear plasma pulse testing on JET are presented. The latter include not only successful detection of fusion fuel cycle and impurity species, but also improved resolution and stability over the state-of-the-art, 15m-cable units on the same analysis station.

Original languageEnglish
Article number112672
JournalFusion Engineering and Design
Volume170
DOIs
StatePublished - Sep 2021

Funding

This work was funded in part under US Department of Energy Contract No. DE-AC05–00OR22725 with UT-Battelle, LLC. Part of this work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training program 2014–2018 and 2019–2020 under grant agreement No 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission This work was funded in part under US Department of Energy Contract No. DE-AC05?00OR22725 with UT-Battelle, LLC. Part of this work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training program 2014?2018 and 2019?2020 under grant agreement No 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission

FundersFunder number
U.S. Department of EnergyDE-AC05, DE-AC05–00OR22725
H2020 Euratom633053

    Keywords

    • DTE2
    • ITER
    • JET
    • Neutron radiation effects
    • Plasma diagnostics
    • Radiation hardening (electronics)
    • Residual gas analysis
    • Tokamak devices

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