Neutral gas analysis for JET DT operation

Kruezi, U.; Jepu, I.; Sergienko, G.; Delabie, E.; Vartanian, S.; Widdowson, A.

doi:10.1088/1748-0221/15/01/c01032

Cited by 16 publications

(13 citation statements)

References 21 publications

(23 reference statements)

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“…For 98043 and 98044 the first three points disagree with KT5P within the given uncertainties. 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].…”

Section: Discussionsupporting

confidence: 67%

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: Discussionsupporting

confidence: 67%

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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“…Measurements of H, D, and T concentration in the JET sub-divertor region are made with an optical Penning gauge [11,12]. In all T cases reported here n T /n H+D+T > 95%, and n D /n H+D+T < 1%.…”

Section: Preliminary Results From L-h Transition Studies In Tritium P...mentioning

confidence: 90%

Recent progress in L–H transition studies at JET: tritium, helium, hydrogen and deuterium

et al. 2022

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We present an overview of results from a series of L-H transition experiments undertaken at JET since the installation of the ITER-like-wall (JET-ILW), with Beryllium wall tiles and a Tungsten divertor. Tritium, Helium and Deuterium plasmas have been investigated. Initial results in Tritium show ohmic L-H transitions at low density and the power threshold for the L-H transition (PLH) is lower in Tritium plasmas than in Deuterium ones at low densities,while we still lack contrasted data to provide a scaling at high densities. In Helium plasmas there is a notable shift of the density at which the power threshold is minimum (ne,min) to higher values relative to Deuterium and Hydrogen references. Above ne,min(He) the L-H power threshold at high densities is similar for D and He plasmas. Transport modelling in slab geometry shows that in Helium neoclassical transport competes with interchange-driven transport, unlike in Hydrogen isotopes. Measurements of the radial electric field in Deuterium plasmas show that Er shear is not a good indicator of proximity to the L-H transition. Transport analysis of ion heat flux in Deuterium plasmas show a non-linearity as density is decreased below ne,min. Lastly, a regression of the JET-ILW Deuterium data is compared to the 2008 ITPA scaling law.

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“…The concentration of the different hydrogenic species, H, D and T, were continuously monitored with an optical Penning (or species-selective Penning) gauge in the JET subdivertor region as described in references [25,26]. It measures the concentration of one hydrogenic species relative to the total concentration of all hydrogenic species.…”

Section: Experimental Strategy and Dynamics Of L-h Transition Pulsesmentioning

confidence: 99%

The power threshold of H-mode access in mixed hydrogen–tritium and pure tritium plasmas at JET with ITER-like wall

Birkenmeier

Solano²,

Lerche

et al. 2022

Nucl. Fusion

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The heating power to access the high confinement mode (H-mode), PLH, scales approximately inversely with the isotope mass of the main ion plasma species as found in (protonic) hydrogen, deuterium and tritium plasmas in many fusion facilities over the last decades. In first dedicated L-H transition experiments at the Joint European Torus (JET) tokamak facility with the ITER-like wall (ILW), the power threshold, PLH , was studied systematically in plasmas of pure tritium and hydrogen- tritium mixtures at a magnetic field of 1.8 T and a plasma current of 1.7 MA in order to assess whether this scaling still holds in a metallic wall device. The measured power thresholds, PLH, in Ohmically heated tritium plasmas agree well with the expected isotope scaling for metallic walls and the lowest power threshold was found in Ohmic phases at low density. The measured power thresholds in ion cyclotron heated plasmas of pure tritium or hydrogen-tritium mixtures are significantly higher than the expected isotope mass scaling due to higher radiation levels. However, when the radiated power is taken into account, the ion cyclotron heated plasmas exhibit similar power thresholds as a neutral beam heated plasma, and are close to the scaling. The tritium plasmas in this study tended to higher electron heating fractions and, when heated with ion cyclotron waves, to relatively higher radiation fractions compared to other isotopes potentially impeding access to sustained H-modes.

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Neutral gas analysis for JET DT operation

Cited by 16 publications

References 21 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

Recent progress in L–H transition studies at JET: tritium, helium, hydrogen and deuterium

The power threshold of H-mode access in mixed hydrogen–tritium and pure tritium plasmas at JET with ITER-like wall

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