Publisher’s Note: “An FPGA-based instrumentation platform for use at deep cryogenic temperatures” [Rev. Sci. Instrum. 87, 014701 (2016)]

Lamb, I. D. Conway; Colless, James; Hornibrook, J. M.; Pauka, Sebastian; Waddy, S. J.; Frechtling, Michael; Reilly, David

doi:10.1063/1.4941329

Cited by 5 publications

(5 citation statements)

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“…Various diagnostics were used to obtain the background plasma parameters. The Thomson scattering diagnostic [15] provided measurements of n e and T e , while the ion temperature, T i , and toroidal velocity, v φ , measurements were obtained from CX measurements of carbon [16]. Z ef f profiles are based on the He 2+ and C 6+ density measurements made by the RGB diagnostic [17] (described in the next subsection).…”

Section: Plasma Scenariosmentioning

confidence: 99%

Neoclassical and gyrokinetic analysis of time-dependent helium transport experiments on MAST

et al. 2014

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Time-dependent helium gas puff experiments have been performed on the Mega Ampère Spherical Tokamak (MAST) during a two point plasma current scan in L-mode and a confinement scan at 900 kA. An evaluation of the He II (n = 4 → 3) spectrum line induced by charge exchange suggests anomalous rates of diffusion and inward convection in the outer regions of both L-mode plasmas. Similar rates of diffusion are found in the H-mode plasma, however these rates are consistent with neoclassical predictions. The anomalous inward pinch found in the core of L-mode plasmas is also not apparent in the H-mode core. Linear gyrokinetic simulations of one flux surface in L-mode using the gs2 and gkw codes find that equilibrium flow shear is sufficient to stabilise ITG modes, consistent with BES observations, and suggest that collisionless TEMs may dominate the anomalous helium particle transport. A quasilinear estimate of the dimensionless peaking factor associated with TEMs is in good agreement with experiment. Collisionless TEMs are more stable in H-mode because the electron density gradient is flatter. The steepness of this gradient is therefore pivotal in determining the inward neoclassical particle pinch and the particle flux associated with TEM turbulence.

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Section: Plasma Scenariosmentioning

confidence: 99%

Neoclassical and gyrokinetic analysis of time-dependent helium transport experiments on MAST

et al. 2014

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“…The Thomson scattering system measures the electron temperature T e and density n e profiles with a radial resolution and sampling rate of 10 mm and 240 Hz respectively [25]. Spectrally resolved CX measurements of C VI from the CELESTE-3 diagnostic are used to deduce the ion temperature T i and toroidal rotation V φ profiles with radial and temporal resolutions of 1 cm and 4 ms [26]. Radial profiles of the He 2+ and C 6+ concentration (typically of the order of ∼ 1 % and ∼ 0.1 % respectively) are derived from calibrated CX measurements from the RGB filtered imaging diagnostic [27] and used to determine self-consistent profiles of Z ef f and the main ion density n i [24].…”

Section: Plasma Scenario and Diagnosticsmentioning

confidence: 99%

“…Measurements of the active CX C VI n = 8 → 7 (λ = 529.1 nm) and N VII n = 9 → 8 (λ = 566.9 nm) spectral line intensities, induced by NBI, have been made with a spectrometer and multi-chord setup. For carbon we use the existing CELESTE-3 diagnostic [26] (primarily measuring T i and V φ ) consisting of 64 active and passive tangential fibres with a spatial resolution of ∼ 1 cm. A similar setup is used for nitrogen but with 16 active and passive fibres with a spatial resolution of ∼ 5 cm.…”

Section: Plasma Scenario and Diagnosticsmentioning

confidence: 99%

Charge dependence of neoclassical and turbulent transport of light impurities on MAST

Henderson

Garzotti

Casson

et al. 2015

Plasma Phys. Control. Fusion

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Carbon and nitrogen impurity transport coefficients are determined from gas puff experiments carried out during repeat L-mode discharges on the Mega-Amp Spherical Tokamak (MAST) and compared against a previous analysis of helium impurity transport on MAST. The impurity density profiles are measured on the lowfield side of the plasma, therefore this paper focuses on light impurities where the impact of poloidal asymmetries on impurity transport is predicted to be negligible. A weak screening of carbon and nitrogen is found in the plasma core, whereas the helium density profile is peaked over the entire plasma radius. Both carbon and nitrogen experience a diffusivity of the order of 10 m 2 /s and a strong inward convective velocity of ∼ 40 m/s near the plasma edge, and a region of outward convective velocity at midradius. The measured impurity transport coefficients are consistent with neoclassical Banana-Plateau predictions within ρ ≤ 0.4. Quasi-linear gyrokinetic predictions of the carbon and helium particle flux at two flux surfaces, ρ = 0.6 and ρ = 0.7, suggest that trapped electron modes are responsible for the anomalous impurity transport observed in the outer regions of the plasma. The model, combining neoclassical transport with quasi-linear turbulence, is shown to provide reasonable estimates of the impurity transport coefficients and the impurity charge dependence.

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“…Adduci in the Ames Laboratory. It has been described in detail elsewhere (39,40,41). A simplified block diagram of this spectrometer is shown in…”

Section: B Pulsed Nmr Spectrometermentioning

confidence: 99%

“…The pulse programmer used in the spectrometer system is a modifi cation of the Conway-Cotts design (40). A detailed description can be found in (41).…”

Section: Pulse Programmermentioning

confidence: 99%

An NMR study of hydrogen diffusion in metal hydrides containing paramagnetic impurities

Phua

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INFORMATION TO USERSThis reproduction was made from a copy of a document sent to us for microfilming. While the most advanced technology has been used to photograph and reproduce this document, the quality of the reproduction is heavily dependent upon the quality of the material submitted.The following explanation of techniques is provided to help clarify markings or notations which may appear on this reproduction. 1. The sign or "target" for pages apparently lacking from the document photographed is "Missing Page(s)". If it was possible to obtain the missing page(s) or section, they are spliced into the film along with adjacent pages. This may have necessitated cutting through an image and duplicating adjacent pages to assure complete continuity.2. When an image on the film is obliterated with a round black mark, it is an indication of either blurred copy because of movement during exposure, duplicate copy, or copyrighted materials that should not have been filmed. For blurred pages, a good image of the page can be found in the adjacent frame. If copyrighted materials were deleted, a target note will appear listing the pages in the adjacent frame.3. When a map, drawing or chart, etc., is part of the material being photographed, a definite method of "sectioning" the material has been followed. It is customary to begin filming at the upper left hand comer of a large sheet and to continue from left to right in equal sections with small overlaps. If necessary, sectioning is continued again-beginning below the first row and continuing on until complete.

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Publisher’s Note: “An FPGA-based instrumentation platform for use at deep cryogenic temperatures” [Rev. Sci. Instrum. 87, 014701 (2016)]

Cited by 5 publications

References 0 publications

Neoclassical and gyrokinetic analysis of time-dependent helium transport experiments on MAST

Neoclassical and gyrokinetic analysis of time-dependent helium transport experiments on MAST

Charge dependence of neoclassical and turbulent transport of light impurities on MAST

An NMR study of hydrogen diffusion in metal hydrides containing paramagnetic impurities

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