Development of novel fuel ion ratio diagnostic techniques

Korsholm, S. B.; Stejner, M.; Conroy, S.; Ericsson, Göran; Gorini, G.; Tardocchi, M.; Hellermann, M. von; Jaspers, Rje Roger; Lischtschenko, O.; Delabie, E.; Bindslev, H.; Furtula, Vedran; Leipold, F.; Méo, F.; Michelsen, Poul; Moseev, D.; Nielsen, S. K.; Salewski, M.

doi:10.1063/1.3460634

Cited by 10 publications

(13 citation statements)

References 4 publications

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“…The backscattering system is sensitive to fast ions with pitch |p| < 0.5 − 0.9, depending on the ion energy and the frequency shift of the scattered radiation. Its viewing geometry makes it easy to retrofit it with a CTS-based fuel ion ratio diagnostic [43][44][45][46]. On the other hand, the forward scattering system would be sensitive to co-and counter-passing fast ions at various energies with pitch |p| > 0.6 − 0.8.…”

Section: Discussionmentioning

confidence: 99%

On velocity space interrogation regions of fast-ion collective Thomson scattering at ITER

et al. 2011

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The collective Thomson scattering (CTS) diagnostic proposed for ITER is designed to measure projected 1D fast-ion velocity distribution functions at several spatial locations simultaneously. The frequency shift of scattered radiation and the scattering geometry place fast ions that caused the collective scattering in well-defined regions in velocity space, here dubbed interrogation regions. Since the CTS instrument measures entire spectra of scattered radiation, many different interrogation regions are probed simultaneously. We here give analytic expressions for weight functions describing the interrogation regions, and we show typical interrogation regions of the proposed ITER CTS system. The backscattering system with receivers on the low-field side is sensitive to fast ions with pitch |p| = |v∥/v| < 0.5–0.9 depending on the ion energy and the frequency shift of the scattered radiation. A forward scattering system with receivers on the high-field side would be sensitive to co- and counter-passing fast ions in narrow interrogation regions with pitch |p| > 0.6–0.8. Additionally, we use weight functions to reconstruct 2D fast-ion distribution functions, given two projected 1D velocity distribution functions from simulated simultaneous measurements with the back- and forward scattering systems.

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Section: Discussionmentioning

confidence: 99%

On velocity space interrogation regions of fast-ion collective Thomson scattering at ITER

et al. 2011

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“…n T /n D has been identified as an important parameter to monitor at ITER for several operating scenarios, with a time resolution of 100 ms, a spatial resolution of a/10, an accuracy of 20%, and for a range of 0.01 < n T /n D < 10 [1], and will likely also be continuously monitored in future high-performance fusion devices such as DEMO. The fuel ion ratio has, in addition to neutron spectrometry, previously been suggested to be measured through collective Thomson scattering and charge exchange recombination spectrometry [1,2]. In preparation for the DTE2 campaign planned for the end of 2021, tritium was added to the Joint European Torus (JET) plasma with varying concentrations for the first time since the deuterium-tritium experimental campaign (DTE1) in 1997 and the trace tritium experimental campaign (TTE) in 2003.…”

Section: Introductionmentioning

confidence: 99%

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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“…However, it is not clear if the fuel ion ratio can be determined in the plasma center (ρ < 0.3) with the diagnostic set currently included in the ITER baseline design. Therefore additional approaches are desired [1,2]. Microwave-based CTS diagnostics are well suited for reactor environments and provide access to the dynamics of confined ion populations by measuring the spectrum of probe radiation scattered by plasma fluctuations.…”

Section: Introductionmentioning

confidence: 99%

Principles of fuel ion ratio measurements in fusion plasmas by collective Thomson scattering

Stejner¹,

Nielsen²,

Bindslev³

et al. 2011

Plasma Phys. Control. Fusion

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For certain scattering geometries collective Thomson scattering (CTS) measurements are sensitive to the composition of magnetically confined fusion plasmas. CTS therefore holds the potential to become a new diagnostic for measurements of the fuel ion ratio-i.e. the tritium to deuterium density ratio. Measurements of the fuel ion ratio will be important for plasma control and machine protection in future experiments with burning fusion plasmas. Here we examine the theoretical basis for fuel ion ratio measurements by CTS. We show that the sensitivity to plasma composition is enhanced by the signatures of ion cyclotron motion and ion Bernstein waves which appear for scattering geometries with resolved wave vectors near perpendicular to the magnetic field. We investigate the origin and properties of these features in CTS spectra and give estimates of their relative importance for fuel ion ratio measurements.

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Development of novel fuel ion ratio diagnostic techniques

Cited by 10 publications

References 4 publications

On velocity space interrogation regions of fast-ion collective Thomson scattering at ITER

On velocity space interrogation regions of fast-ion collective Thomson scattering at ITER

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

Principles of fuel ion ratio measurements in fusion plasmas by collective Thomson scattering

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