A 130 point Nd:YAG Thomson scattering diagnostic on MAST

Scannell, R.; Walsh, M. J.; Dunstan, M. R.; Figueiredo, J.; Naylor, G.; O’Gorman, T.; Shibaev, S.; Gibson, K. J.; Wilson, H. R.

doi:10.1063/1.3460628

Cited by 68 publications

(62 citation statements)

References 10 publications

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“…For these Ohmic plasmas, where no core ion measurements are usually available, we assume T e = T i and n e = n i (typically for the core plasma in MAST Z ef f 1.2), and use Thomson scattering [31] for T e and n e . Most shots in the database were purely Ohmic, but two did have short duration (10 ms) NBI blips for charge exchange recombination spectroscopy [32].…”

Section: Comparison Between Model and Experimentsmentioning

confidence: 99%

Dependence of intrinsic rotation reversals on collisionality in MAST

Hillesheim¹,

Parra²,

Barnes³

et al. 2015

Nucl. Fusion

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Tokamak plasmas rotate even without external injection of momentum. A Doppler backscattering system installed at MAST has allowed this intrinsic rotation to be studied in Ohmic L-mode and Hmode plasmas, including the first observation of intrinsic rotation reversals in a spherical tokamak. Experimental results are compared to a novel 1D model, which captures the collisionality dependence of the radial transport of toroidal angular momentum due to the effect of neoclassical flows on turbulent fluctuations. The model is able to accurately reproduce the change in sign of core toroidal rotation, using experimental density and temperature profiles from shots with rotation reversals as inputs and no free parameters fit to experimental data.

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Section: Comparison Between Model and Experimentsmentioning

confidence: 99%

Dependence of intrinsic rotation reversals on collisionality in MAST

Hillesheim¹,

Parra²,

Barnes³

et al. 2015

Nucl. Fusion

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“…Profiles of density and electron temperature were measured with high resolution Thomson scattering (HRTS) [24] around the time when the filaments were analysed. The proximity in time with an HRTS measurement was another selection criterion for the filaments.…”

Section: Experimental Conditionsmentioning

confidence: 99%

Multi-code analysis of scrape-off layer filament dynamics in MAST

Militello

Walkden

Farley

et al. 2016

Plasma Phys. Control. Fusion

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“…The world-largest merging device: MAST [27] (Mega Ampere Spherical Tokamak) achieved remarkable success in those issues. Although the absence of in-situ probe diagnostics around diffusion region complicates the detailed discussion with magnetics, reconnection heating exceeds ∼1keV at maximum [19] both for ions and electrons; in addition, the spatial resolution of Ruby and YAG Thomson scattering diagnostics were recently increased up to 300 and 130 channels respectively [28][29] [30]. A new 32 chord tomographic ion Doppler spectroscopy [22] measurement has also been installed on midplane with the viewing range around core reconnection region inside r < 0.8m where the existing charge exchange recombination spectroscopy measurement cannot measure due to the limitation of the…”

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confidence: 99%

Electron and Ion Heating Characteristics during Magnetic Reconnection in the MAST Spherical Tokamak

Tanabe

Yamada²,

Watanabe

et al. 2015

Phys. Rev. Lett.

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Local electron and ion heating characteristics during merging reconnection startup on the MAST spherical tokamak have been revealed for the first time using a 130 channel YAG-TS system and a new 32 chord ion Doppler tomography diagnostic. 2D local profile measurement of Te, ne and Ti detect highly localized electron heating at the X point and bulk ion heating downstream. For the push merging experiment under high guide field condition, thick layer of closed flux surface formed by reconnected field sustains the heating profile for more than electron and ion energy relaxation time τ E ei ∼ 4 − 10ms, both heating profiles finally form triple peak structure at the X point and downstream. Toroidal guide field mostly contributes the formation of peaked electron heating profile at the X point. The localized heating increases with higher guide field, while bulk downstream ion heating is unaffected by the change in the guide field under MAST conditions (Bt > 3Brec).PACS numbers: 52.35. Vd, 52.55.Fa, 52.72.+v Magnetic reconnection is a fundamental process which converts the magnetic energy of reconnecting fields to kinetic and thermal energy of plasma through the breaking and topological rearrangement of magnetic field lines. Recent satellite observations of solar flares revealed several important signatures of reconnection heating. In the solar flares, hard X-ray spots appear at loop-tops of coronas together with another two foot-point spots on the photosphere. The loop-top hot spots are considered to be caused by fast shocks formed in the down-stream of reconnection outflow [3]. The two-dimensional (2D) measurements of the Hinode spectrometer documented a significant broadening of Ca line-width downstream of reconnection [4]. These phenomena strongly suggest direct ion heating by reconnection outflow. On the other hand, the V-shape high electron temperature region was found around X-line of reconnection as an possible evidence of slow shock structure [5]. However, those heating characteristics of reconnection are still under serious discussion, indicating that direct evidence for the reconnection heating mechanisms should be provided by a proper laboratory experiment. Since 1986 the merging of two toroidal plasmas (flux tubes) has been studied in a number of experiments: TS-3

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A 130 point Nd:YAG Thomson scattering diagnostic on MAST

Cited by 68 publications

References 10 publications

Dependence of intrinsic rotation reversals on collisionality in MAST

Dependence of intrinsic rotation reversals on collisionality in MAST

Multi-code analysis of scrape-off layer filament dynamics in MAST

Electron and Ion Heating Characteristics during Magnetic Reconnection in the MAST Spherical Tokamak

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