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

Pégouriè, B.; Vartanian, S.; Goniche, M.; Delabie, E.; Eester, D. Van; Lerche, E.; Sips, G.; Borodkina, I.; Douai, D.; Jepu, I.; Kruezi, U.; Matthews, G. F.; Widdowson, A.; Contributors, Jet

doi:10.1088/1741-4326/ab4c5a

Cited by 12 publications

(6 citation statements)

References 17 publications

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“…However, after a recent upgrade in preparation for DTE2 [14], KT5P reached a lower detection limit of T concentrations on the level of 1%, which is close to the first three points according to the TOFOR measurement. Further, the measured concentration, derived from fitting the optical spectra from the Penning gauge, will stay in the range of 0%-1% even when no T is present [15]. The TOFOR and KT5P measurements agree within the given uncertainties for the points after 11 s at which the T concentration is on the level of 2%.…”

Section: Discussionmentioning

confidence: 54%

Determining the fuel ion ratio for D(T) and T(D) plasmas at JET using neutron time-of-flight spectrometry

Eriksson

Conroy

Ericsson

et al. 2022

Plasma Phys. Control. Fusion

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The fusion fuel ion ratio, nT/nD, is an important plasma parameter that needs to be tuned to maximize the power of a tokamak type fusion reactor. It is recognized as a parameter required for optimizing several ITER operating scenarios, and will likely be continuously monitored in future high-performance fusion devices such as DEMO. Tritium was recently introduced in the Joint European Torus (JET) plasma for the first time since the 1997 DTE1 and 2003 TTE campaigns, enabling the possibility to investigate fuel ion ratios. We present a method for measuring nT/nD using neutron time-of-flight (TOF) spectrometry. By fitting the measured neutron spectral features, the relative reaction rate intensities between different ion species can be inferred, from which the fuel ion ratio can be extracted for a corresponding modeled reactivity. Unlike previous measurements of nT/nD using neutron spectrometry, we utilize the neutron energy continuum produced in the three-body TT reaction to determine the fuel ion ratio for plasmas with large concentrations of tritium. Further, the use of neutron TOF spectrometry has never previously been demonstrated for evaluating nT/nD. The method is applied to TOF spectra acquired with TOFOR (JET name KM11) and shown to be consistent with the optical JET diagnostic KT5P which uses optical spectroscopy of a modified Penning gauge plasma to measure tritium and deuterium concentrations in the divertor exhaust gas.

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Section: Discussionmentioning

confidence: 54%

Determining the fuel ion ratio for D(T) and T(D) plasmas at JET using neutron time-of-flight spectrometry

Eriksson

Conroy

Ericsson

et al. 2022

Plasma Phys. Control. Fusion

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“…Plasma pulse-resolving exhaust gas analysis, including Penning optical spectroscopy, was recently upgraded to assure achieving this detection limit capability and maintaining it through DTE2 [169,170]. Complementing this capability and that of the edge spectroscopy, the plasma core isotopic ratio can be inferred from neutrons diagnostics when including the measured profiles and FI calculations [110].…”

Section: Wall Cleaning and Isotopic And Plasma Species Content Monito...mentioning

confidence: 99%

Overview of JET results for optimising ITER operation

et al. 2022

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The JET 2019-2020 scientific and technological programme exploited the results of years of concerted scientific and engineering work, including the ITER-like wall (ILW: Be wall and W divertor) installed in 2010, improved diagnostic capabilities now fully available, a major Neutral Beam Injection (NBI) upgrade providing record power in 2019-2020, and tested the technical & procedural preparation for safe operation with tritium. Research along three complementary axes yielded a wealth of new results. Firstly, the JET plasma programme delivered scenarios suitable for high fusion power and alpha particle physics in the coming D-T campaign (DTE2), with record sustained neutron rates, as well as plasmas for clarifying the impact of isotope mass on plasma core, edge and plasma-wall interactions, and for ITER pre-fusion power operation. The efficacy of the newly installed Shattered Pellet Injector for mitigating disruption forces and runaway electrons was demonstrated. Secondly, research on the consequences of long-term exposure to JET-ILW plasma was completed, with emphasis on wall damage and fuel retention, and with analyses of wall materials and dust particles that will help validate assumptions and codes for design & operation of ITER and DEMO. Thirdly, the nuclear technology programme aiming to deliver maximum technological return from operations in D, T and D-T benefited from the highest D-D neutron yield in years, securing results for validating radiation transport and activation codes, and nuclear data for ITER.

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“…The tritium content in the pumped gas measured by the subdivertor OGA [24,25] during and right after ICWC discharges and divertor plasma pulses is shown in figure 5. On days 5 and 6, only few short ICWC discharges were executed in order to improve matching of ICRF antennas for efficient coupling to the low density (typically 10 17 -10 18 m −3 ) ICWC plasmas.…”

Section: Isotopic Content Monitoringmentioning

confidence: 99%

“…Since the contribution of thermal outgassing by baking is expected to be negligible by that time, as will be shown in the next section dedicated to the T removal analysis, this reduction can be attributed to both ICWC discharges and overnight GDC phases, the effect of the latter on the T fraction being particularly visible in the post-discharge phase of ICWC plasmas in figure 5. It has to be noted, however, that the detection limit of the sub-divertor OGA is determined by the resolution of the partially overlapping T α and D α spectral lines affected by the signal to noise ratio, especially at low light intensities, and is typically 1%-2% T in D plasmas [24,25]. On day 10, when the JET main chamber walls were cooled down to 110 • C in the morning and then gradually warmed up to 200 • C over the course of the day, the measured isotopic content fluctuated between 1% and 2% without any clear trend with respect to the number of operated ICWC pulses or wall temperature.…”

Section: Isotopic Content Monitoringmentioning

confidence: 99%

Tritium removal from JET-ILW after T and D–T experimental campaigns

Matveev,

Douai,

Wauters

et al. 2023

Nucl. Fusion

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After the second Deuterium–Tritium Campaign (DTE2) in the JET tokamak with the ITER-Like Wall (ILW) and full tritium campaigns that preceded and followed after the DTE2, a sequence of fuel recovery methods was applied to promote tritium removal from wall components. The sequence started with several days of baking of the main chamber walls at 240 °C and at 320 °C. Subsequently, baking was superimposed with Ion-Cyclotron Wall Conditioning (ICWC) and Glow Discharge Conditioning (GDC) cleaning cycles in deuterium. Diverted plasma operation in deuterium with different strike point configurations, including a Raised Inner Strike Point (RISP) configuration, and with different plasma heating—Ion Cyclotron Resonance Frequency (ICRF) and Neutral Beam Injection (NBI)—concluded the cleaning sequence. Tritium content in plasma and in the pumped gas was monitored throughout the experiment. The applied fuel recovery methods allowed reducing the residual tritium content in deuterium NBI-heated plasmas to about 0.1% as deduced from neutron rate measurements. This value is well below the requirement of 1% set by the maximum 14 MeV fusion neutron budget allocated in the ensuing deuterium plasma campaign. The quantified tritium removal over the course of the experiment was 13.4 ± 0.7 × 10 22 atoms or 0.67 ± 0.03 g with ∼58% attributed to baking, ∼12.5% to ICWC, ∼26% to GDC, and ∼3.5% to first low power RISP plasmas. The experimentally estimated amount of removed tritium is in good agreement with long-term tritium accounting by the JET tritium reprocessing plant, in which the unaccounted amount was reduced by 0.71 g after the cleaning experiment.

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

Cited by 12 publications

References 17 publications

Determining the fuel ion ratio for D(T) and T(D) plasmas at JET using neutron time-of-flight spectrometry

Determining the fuel ion ratio for D(T) and T(D) plasmas at JET using neutron time-of-flight spectrometry

Overview of JET results for optimising ITER operation

Tritium removal from JET-ILW after T and D–T experimental campaigns

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