M. J. Lanctot
The first quantitative comparison of linear ideal magnetohydrodynamic MHD theory with external magnetic measurements of the nonaxisymmetric plasma perturbation driven by external long-wavelength magnetic fields in high-temperature tokamak plasmas is presented. The comparison yields good within 20% agreement for plasma pressures up to 75% of the ide…
PublishedI. T. Chapman R. Scannell W. A. Cooper J. P. Graves R. J. Hastie G. Naylor A. Zocco
Thomson scattering measurements with subcentimeter spatial resolution have been made during a sawtooth crash in a Mega Ampere Spherical Tokamak fusion plasma. The unparalleled resolution of the temperature profile has shed new light on the mechanisms that underlie the sawtooth. As magnetic reconnection occurs, the temperature gradient at the island…
PublishedG. Naylor
The MAST Thomson scattering diagnostic has recently been upgraded to make electron density and temperature measurements at 130 points across the 1.5 m diameter of the plasma. The new system is able to take 240 measurements per second using eight Nd:YAG lasers, each running at 30 Hz. The exact firing time of these lasers is adjusted with 100 ns prec…
PublishedL Garzotti L Baylor F Köchl B Pégourié M Valovic K B Axon J Dowling C Gurl G P Maddison H Nehme T O’Gorman A Patel M Price R Scannell M Walsh
Pellet material deposited in a tokamak plasma experiences a drift towards the low field side of the torus induced by the magnetic field gradient. Plasma fuelling in ITER relies on the beneficial effect of this drift to increase the pellet deposition depth and fuelling efficiency. It is therefore important to analyse this phenomenon in present machi…
PublishedM.Barnes W.Dorland T.Tatsuno
Many plasmas of interest to the astrophysical and fusion communities are weakly collisional. In such plasmas, small scales can develop in the distribution of particle velocities, potentially affecting observable quantities such as turbulent fluxes. Consequently, it is necessary to monitor velocity space resolution in gyrokinetic simulations. In thi…
PublishedJ.W.S. Cook S.C. Chapman
We present first principles simulations of the direct collisionless coupling of the free energy of fusionborn ions into electron current in a magnetically confined fusion plasma. These simulations demonstrate, for the first time, a key building block of some ‘‘alpha channeling’’ scenarios for tokamak experiments. Spontaneously excited obliq…
PublishedM. J. Hole G. Von Nessi D. Pretty J. Howard B. Blackwell J. Svensson L. C. Appel
Recently, Bayesian probability theory has been used at a number of experiments to fold uncertainties and interdependencies in the diagnostic data and forward models, together with prior knowledge of the state of the plasma, to increase accuracy of inferred physics variables. A new probabilistic framework, MINERVA, based on Bayesian graphical models…
PublishedG. De Temmerman M.Bacharis J.Dowling S.Lisgo
In this contribution, we report on experiments performed in MAST to investigate dust creation, transport and influence on plasma performance. The exceptional diagnostic access of MAST allows stereoscopic imaging of dust particles motion in both the divertor and the main chamber, utilising fast infrared cameras. This technique allows the 3D trajecto…
PublishedA. Thyagaraja
Inviscid, incompressible hydrodynamics and incompressible ideal magnetohydrodynamics MHD share many properties such as time-reversal invariance of equations, conservation laws, and certain topological features. In three dimensions, these systems may lead to singular solutions involving vortex and current sheets. While dissipative viscoresistive eff…
PublishedJ.M. Dewhurst B. Hnat R.O. Dendy
The effect of finite Larmor radius on the transport of passive charged test particles moving in turbulent electrostatic fields is investigated. The turbulent field is governed by a flexible model which is able to produce turbulence where zonal flows are damped or free to self-generate. A subtle interplay between trapping in small scale vortices and…
Published