ELM characteristics in MAST

Kirk, A.; Counsell, G.; Wilson, H. R.; Ahn, J.-W.; Akers, R.; Arends, E. R.; Dowling, J.; Martin, Richard L.; Meyer, H.; Hole, Matthew; Price, M.; Snyder, P. B.; Taylor, D.; Walsh, M. J.; Yang, Yilin

doi:10.1088/0741-3335/46/3/009

Cited by 72 publications

(106 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In MAST the value found experimentally by probe measurements [27] is s ELM MHD % 87 ls. This value agrees with the energy loss timescale caused by an explosive finger-like instability, which is described by non-linear MHD ballooning calculation s ELM MHD % s explosive…”

Section: Power Load Characteristics For the Divertor Target Plates Dumentioning

confidence: 78%

“…In ELM resolved probe studies in TCV [25], JET [26], ASDEX Upgrade [14], MAST [27] and DIII-D [19], a delay in the response of the divertor plasma to pedestal energy ions relative to pedestal energy electrons was observed as expected for a convective transport of energy. Studies of the soft X-ray emission from the divertor target surfaces during the start phase of ELMs in JET suggest bremsstrahlung emission caused by fast electrons, consistent with the idea that these electron losses would then lead to a sheath potential restricting further losses to the ion loss time [28].…”

Section: Power Load Characteristics For the Divertor Target Plates Dumentioning

confidence: 96%

See 1 more Smart Citation

Power deposition onto plasma facing components in poloidal divertor tokamaks during type-I ELMs and disruptions

Eich

Herrmann

Pautasso

et al. 2005

Journal of Nuclear Materials

View full text Add to dashboard Cite

Section: Power Load Characteristics For the Divertor Target Plates Dumentioning

confidence: 78%

Section: Power Load Characteristics For the Divertor Target Plates Dumentioning

confidence: 96%

Power deposition onto plasma facing components in poloidal divertor tokamaks during type-I ELMs and disruptions

Eich

Herrmann

Pautasso

et al. 2005

Journal of Nuclear Materials

View full text Add to dashboard Cite

“…In recent years much attention was devoted to ELM filaments [28][29][30] (Fig. 8 right), but it has been long known that the intermittent L-mode transport is also filamentary [31,32] (Fig.…”

Section: Sol Modelling and Edge Filamentsmentioning

confidence: 99%

Overview of physics results from MAST

Raman¹,

Ahn²,

Allain³

et al. 2011

Nucl. Fusion

View full text Add to dashboard Cite

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...

show abstract

“…First, maximise the radiated power from the main plasma whilst maintaining adequate purity (the small volume means that highly radiating species, such as tungsten probably have to be used). Second, use the experience from MAST where a double null configuration leads to the vast majority of the power going to the outboard targets (>95% in L-mode and during ELMs [16]). Third, develop a flowing divertor target (e.g.…”

Section: Plasma Power Balance and Exhaustmentioning

confidence: 99%