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Title: Sub-divertor fuel isotopic content detection limit for JET and its impact on ICRF core heating and DTE2 operation

Journal Article · · Nuclear Fusion
ORCiD logo [1];  [2];  [2];  [2]; ORCiD logo [1];  [3];  [3];  [4];  [5];  [2];  [4];  [4];  [4]; ORCiD logo [4]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  2. French Alternatives Energies and Atomic Energy Commission (CEA), Saint Paul-lez-Durance (France). Inst. for Magnetic Fusion Research (IRFM)
  3. Royal Military Academy, Brussels (Belgium)
  4. Culham Science Centre (United Kingdom and Northern Ireland)
  5. Forschungszentrum Jülich GmbH (Germany)
+ Show Author Affiliations

The ability to detect and control fuel isotopic content down to a 1% concentration level is greatly important for the upcoming JET DTE2 campaign, as well as its associated TT and DD phases. A reduction of H minority concentration even from 2% down to 1% is shown in this paper to have significant impact on the effectiveness of ion cyclotron range of frequencies core heating, while the ability to maintain T or D concentration at or below 1% is critical to limiting fusion neutron generation in the DD and TT phases, correspondingly. The sub-divertor measurement of (global) isotopic concentration, based on Penning-activated optical spectroscopy, can deliver minimally this 1% detection for DTE2 as long as light collection from the Penning emission can be optimized and gradual window transmission deterioration can be minimized. Here, this is simulated with a statistical analysis developed to understand the uncertainty sources in the JET DTE1 data, as well as to guide the optimization of an upgraded, fuel-isotopic content (and helium-ash concentration) gas analysis system for the JET divertor in preparation for DTE2. While this random error can be reduced to allow measurement substantially below 1% concentration, analysis also shows a systematic error of up to 1% understood to be due to plasma–surface interactions in the Penning excitation, suggesting that 1% may still be the low-end limit for the sub-divertor measurement, unless a Penning-source conditioning approach is also developed.

Research Organization:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Organization:
USDOE Office of Science (SC); Euratom
Contributing Organization:
EUROfusion Consortium; JET ICRH Team; JET Contributors
Grant/Contract Number:
AC05-00OR22725; 633053
OSTI ID:
1649148
Journal Information:
Nuclear Fusion, Vol. 60, Issue 1; ISSN 0029-5515
Publisher:
IOP ScienceCopyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 6 works
Citation information provided by
Web of Science

References (15)

Overview of the JET preparation for deuterium–tritium operation with the ITER like-wall text January 2019
Tritium concentration measurements in the Joint European Torus divertor by optical spectroscopy of a Penning discharge journal January 1999
Ion cyclotron resonance heating for tungsten control in various JET H-mode scenarios journal March 2017
Improving accuracy of Penning gauge spectroscopy for the determination of hydrogen isotope H/D ratios journal November 2017
Application of a species-selective Penning gauge to the measurement of neon and hydrogen-isotope partial pressures in the plasma boundary journal January 1997
Overview of ITER physics deuterium-tritium experiments in JET journal February 1999
Optimization of ICRH for core impurity control in JET-ILW journal February 2016
High fusion performance from deuterium-tritium plasmas in JET journal February 1999
Extending helium partial pressure measurement technology to JET DTE2 and ITER journal October 2016
Instrumentation for the upgrade to the JET core charge-exchange spectrometers journal October 2018
Overview of the JET preparation for deuterium–tritium operation with the ITER like-wall journal August 2019
Determination of isotope ratio in the divertor of JET-ILW by high-resolution H α spectroscopy: H–D experiment and implications for D–T experiment journal February 2019
Minority and mode conversion heating in ( 3 He)–H JET plasmas journal June 2012
Fuel recovery experiments with isotopic plasma wall changeover during long discharges in Tore Supra journal February 2013
Control of the hydrogen:deuterium isotope mixture using pellets in JET journal September 2019

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