Title: Neutral gas analysis for JET DT operation

Abstract

Neutral gas analysis, the measurement and evaluation of total and partial pressures, is a key technique to study the impact of neutral gas dynamics on retention, recycling and release processes of fuel or impurity species in fusion devices. At JET, the experiment closest to ITER in terms of operating parameters and size, various detectors and techniques for partial pressure and total pressure measurements are deployed together to characterise neutral gas dynamics during and after plasma operation on various toroidal and poloidal locations. An extensive modification of JET's sub-divertor neutral gas diagnostic system aims at retaining and extending established measurement capabilities in the forthcoming Deuterium-Tritium (DT) experiments (DTE2). To achieve DT compatibility, a separation of radiation-sensitive electronics from the sensor and adequate radiation shielding is required, as well as utilisation of a DT compatible differential pumping system with adjustable throughput to account for the strong pressure variation in the sub-divertor region. Finally, the sub-divertor neutral gas diagnostic will be equipped with multiple Residual Gas Analysers (RGAs), utilising quadrupole mass spectrometry and electrostatic ion-trap-principles, all operating with remote electronics located behind the biological radiation shield. These RGAs will record data in a fast selected discrete mass mode during plasma pulses (cycle ~2more » s) and will automatically switch back to continuous data recording (cycle ~100 s) afterwards. They will be complemented by a newly improved Penning gauge spectroscopy configuration in particular supporting the He and D₂ separation relevant for DT operation. The distance between these devices and their associated control unit is typically 15m . A newly developed RGA with a cable length of 80 m, compatible with the ITER environment, will also be employed for the first time. Finally, this set-up and its operation in DTE2 will provide vital input to the development of the ITER divertor RGA in the most relevant environment currently available.« less

Authors:

Kruezi, Uron ^[1]; Jepu, Ionut ^[2]; Sergienko, G. ^[3]; Klepper, C. Christopher  ^[4];

• Search DOE PAGES for author "Klepper, C. Christopher"
• Search DOE PAGES for ORCID "0000-0001-9107-8337"

Delabie, Ephrem G.  ^[4];

• Search DOE PAGES for author "Delabie, Ephrem G."
• Search DOE PAGES for ORCID "0000-0001-9834-874X"

Vartanian, S. ^[3]; Widdowson, A. ^[5]

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+ Show Author Affiliations

1. Culham Science Centre, Abingdon (United Kingdom); ITER Organization, St. Paul Lez Durance (France)
2. National Inst. for Laser, Plasma and Radiation Physics, Magurele (Romania)
3. Forschungszentrum Juelich (Germany)
4. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
5. Culham Science Centre, Abingdon (United Kingdom)

Publication Date:

Thu Jan 23 00:00:00 EST 2020

Research Org.:

Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Sponsoring Org.:

USDOE

OSTI Identifier:

1811416

Grant/Contract Number:  

AC05-00OR22725

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Instrumentation

Additional Journal Information:

Journal Volume: 15; Journal Issue: 01; Journal ID: ISSN 1748-0221

Publisher:

Institute of Physics (IOP)

Country of Publication:

United States

Language:

English

Subject:

47 OTHER INSTRUMENTATION; plasma diagnostics; interferometry; spectroscopy and imaging; radiation-hard electronics