High speed cine film studies of plasma behaviour and plasma surface interactions in tokamaks

Goodall, Dominic

doi:10.1016/0022-3115(82)90174-x

Cited by 94 publications

(72 citation statements)

References 9 publications

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“…8 right), but it has been long known that the intermittent L-mode transport is also filamentary [31,32] (Fig. 8 middle).…”

Section: Sol Modelling and Edge Filamentsmentioning

confidence: 96%

Overview of physics results from MAST

Raman¹,

Ahn²,

Allain³

et al. 2011

Nucl. Fusion

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Several improvements to the MAST plant and diagnostics have facilitated new studies advancing the physics basis for ITER and DEMO, as well as for future spherical tokamaks. Using the increased heating capabilities P NBI ≤ 3.8 MW H-mode at I p = 1.2 MA was accessed showing that the energy confinement on MAST scales more weakly with I p and more strongly with B t than in the ITER IPB98(y,2) scaling. Measurements of the fuel retention of shallow pellets extrapolate to an ITER particle throughput of 70% of its original design value. The anomalous momentum diffusion, χ φ , is linked to the ion diffusion, χ i , with a Prandtl number close to P φ ≈ χ φ /χ i ≈ 1, although χ i approaches neoclassical values. New high spatially resolved measurements of the edge radial electric field, E r , show that the position of steepest gradients in electron pressure and E r are coincident, but their magnitudes are not linked. The T e pedestal width on MAST scales with the β pol rather than ρ pol . The ELM frequency for type-IV ELMs, new in MAST, was almost doubled using n = 2 resonant magnetic perturbations from a set of 4 external coils (n = 1, 2). A new internal 12 coil set (n ≤ 3) has been commissioned. The filaments in the inter-ELM and L-mode phase are different from ELM filaments, and the characteristics in L-mode agree well with turbulence calculations. A variety of fast particle driven instabilities were studied from 10 kHz saturated fishbone like activity up to 3.8 MHz compressional Alfvén eigenmodes (CAE). The damping rate of ellipticityinduced AE was measured to be 4% using the new internal coils as antennae. Fast particle instabilities also affect the off-axis NBI current drive and lead to fast ion diffusion of the order of 0.5 m 2 /s and reduce the driven current fraction from 40% to 30%. EBW current drive start-up is demonstrated for the first time in a spherical tokamak generating plasma currents up to 55 kA. Many of these studies contributed to the physics basis of a planned upgrade to MAST. Introduction: MAST [1]is one of the two leading tight aspect ratio (A = ε −1 = R/a = 0.85 m/0.65 m ∼ 1.3, I p ≤ 1.5 MA) tokamaks in the world. The hot T ≤ 3 keV, dense n e = (0.1 − 1) × 10 20 m −3 and highly shaped (δ ≤ 0.5, 1.6 ≤ κ ≤ 2.5) plasmas are accessed at moderate toroidal field B t (R = 0.7 m) ≤ 0.62 T and show many similarities to conventional aspect ratio tokamaks. Detailed physics studies using the extensive array of state of the art diagnostics and access to different physics regimes help to consolidate the physics basis for ITER and DEMO [2,3], and explore the viability of future devices based on the spherical tokamak (ST) concept such as a component test facility (CTF) [4] or an advanced power plant [5]. The challenge for today's experiments is to find an integrated scenario that extrapolates to these future devices, in particular to develop plasmas with reduced power load on plasma facing components, notably from edge localised modes (ELM), but high confinement facilitated by internal or edge transport ba...

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“…8 right), but it has been long known that the intermittent L-mode transport is also filamentary [31,32] (Fig. 8 middle).…”

Section: Sol Modelling and Edge Filamentsmentioning

confidence: 96%

Overview of physics results from MAST

Raman¹,

Ahn²,

Allain³

et al. 2011

Nucl. Fusion

View full text Add to dashboard Cite

show abstract

“…Although these movies did not resolve the filament motion, they did suggest that "the filaments are always present but are normally invisible and are illuminated by the presence of atoms or ions emitting visible radiation." 5 It was natural to suspect that these visible filaments in the tokamak edge were associated with edge density fluctuations being measured with Langmuir probes and microwaves scattering at that time, and which were theoretically expected to have a filamentary structure. 1,7 This was confirmed using a poloidal array of visible light detectors in the Caltech tokamak, in which the light fluctuations were highly correlated with nearby Langmuir probe measurements of edge density fluctuations.…”

Section: B History Of Fast Imaging In Magnetic Fusionmentioning

confidence: 99%

“…[5][6][7] Relatively bright field-aligned "filaments" of visible light emission were observed continuously near deuterium or methane gas puff locations at the outer edge of the tokamak. Although these movies did not resolve the filament motion, they did suggest that "the filaments are always present but are normally invisible and are illuminated by the presence of atoms or ions emitting visible radiation."…”

Section: B History Of Fast Imaging In Magnetic Fusionmentioning

confidence: 99%

Invited Review Article: Gas puff imaging diagnostics of edge plasma turbulence in magnetic fusion devices

Zweben

Terry

Stotler

et al. 2017

Review of Scientific Instruments

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Gas puff imaging (GPI) is a diagnostic of plasma turbulence which uses a puff of neutral gas at the plasma edge to increase the local visible light emission for improved space-time resolution of plasma fluctuations. This paper reviews gas puff imaging diagnostics of edge plasma turbulence in magnetic fusion research, with a focus on the instrumentation, diagnostic cross-checks, and interpretation issues. The gas puff imaging hardware, optics, and detectors are described for about 10 GPI systems implemented over the past ∼15 years. Comparison of GPI results with other edge turbulence diagnostic results is described, and many common features are observed. Several issues in the interpretation of GPI measurements are discussed, and potential improvements in hardware and modeling are suggested.

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“…In the model, the equations of motion Eqs. (11)(12)(13)(14) are coupled to the equations for the dust radius Eq. (25), enthalpy Eqs.…”

Section: The Dustt Codementioning

confidence: 99%

Dust-particle transport in tokamak edge plasmas

Pigarov

Krasheninnikov

Soboleva³

et al. 2005

Physics of Plasmas

139

120

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Dust particulates in the size range of 10nm-100µm are found in all fusion devices. Such dust can be generated during tokamak operation due to strong plasma/material-surface interactions. Some recent experiments and theoretical estimates indicate that dust particles can provide an important source of impurities in the tokamak plasma. Moreover, dust can be a serious threat to the safety of next-step fusion devices. In this paper, recent experimental observations on dust in fusion devices are reviewed. A physical model for dust transport simulation, and a newly developed code DUSTT, are discussed. The DUSTT code incorporates both dust dynamics due to comprehensive dust-plasma interactions as well as the effects of dust heating, charging, and evaporation. The code tracks test dust particles in realistic plasma backgrounds as provided by edge-plasma transport codes. Results are presented for dust transport in current and next-step tokamaks. The effect of dust on divertor plasma profiles and core plasma contamination is examined.3

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High speed cine film studies of plasma behaviour and plasma surface interactions in tokamaks

Cited by 94 publications

References 9 publications

Overview of physics results from MAST

Overview of physics results from MAST

Invited Review Article: Gas puff imaging diagnostics of edge plasma turbulence in magnetic fusion devices

Dust-particle transport in tokamak edge plasmas

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