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1. Overview of physics results from MAST towards ITER/DEMO and the MAST Upgrade

Author

Meyer, H., Abel, I. G., Akers, R. J., Allan, A., Allan, S. Y., Appel, L. C., Asunta, O., Barnes, M., Barratt, N. C., Ben Ayed, N., Bradley, J. W., Canik, J., Cahyna, P., Cecconello, Marco, Challis, C. D., Chapman, I. T., Ciric, D., Colyer, G., Conway, N. J., Cox, M., Crowley, B. J., Cowley, S. C., Cunningham, G., Danilov, A., Darke, A., De Bock, M. F. M., De Temmerman, G., Dendy, R. O., Denner, P., Dickinson, D., Dnestrovsky, A. Y., Dnestrovsky, Y., Driscoll, M. D., Dudson, B., Dunai, D., Dunstan, M., Dura, P., Elmore, S., Field, A. R., Fishpool, G., Freethy, S., Fundamenski, W., Garzotti, L., Ghim, Y. C., Gibson, K. J., Gryaznevich, M. P., Harrison, J., Havlickova, E., Hawkes, N. C., Heidbrink, W. W., Hender, T. C., Highcock, E., Higgins, D., Hill, P., Hnat, B., Hole, M. J., Horacek, J., Howell, D. F., Imada, K., Jones, O., Kaveeva, E., Keeling, D., Kirk, A., Kocan, M., Lake, R. J., Lehnen, M., Leggate, H. J., Liang, Y., Lilley, M. K., Lisgo, S. W., Liu, Y. Q., Lloyd, B., Maddison, G. P., Mailloux, J., Martin, R., McArdle, G. J., McClements, K. G., McMillan, B., Michael, C., Militello, F., Molchanov, P., Mordijck, S., Morgan, T., Morris, A. W., Muir, D. G., Nardon, E., Naulin, V., Naylor, G., Nielsen, A. H., O'Brien, M. R., O'Gorman, T., Pamela, S., Parra, F. I., Patel, A., Pinches, S. D., Price, M. N., Roach, C. M., Robinson, J. R., Romanelli, M., Rozhansky, V., Saarelma, S., Sangaroon, S., Saveliev, A., Scannell, R., Seidl, J., Sharapov, S. E., Schekochihin, A. A., Shevchenko, V., Shibaev, S., Stork, D., Storrs, J., Sykes, A., Tallents, G. J., Tamain, P., Taylor, D., Temple, D., Thomas-Davies, N., Thornton, A., Turnyanskiy, M. R., Valovic, M., Vann, R. G. L., Verwichte, E., Voskoboynikov, P., Voss, G., Warder, S. E. V., Wilson, H. R., Wodniak, I., Zoletnik, S., Zagorski, R., Meyer, H., Abel, I. G., Akers, R. J., Allan, A., Allan, S. Y., Appel, L. C., Asunta, O., Barnes, M., Barratt, N. C., Ben Ayed, N., Bradley, J. W., Canik, J., Cahyna, P., Cecconello, Marco, Challis, C. D., Chapman, I. T., Ciric, D., Colyer, G., Conway, N. J., Cox, M., Crowley, B. J., Cowley, S. C., Cunningham, G., Danilov, A., Darke, A., De Bock, M. F. M., De Temmerman, G., Dendy, R. O., Denner, P., Dickinson, D., Dnestrovsky, A. Y., Dnestrovsky, Y., Driscoll, M. D., Dudson, B., Dunai, D., Dunstan, M., Dura, P., Elmore, S., Field, A. R., Fishpool, G., Freethy, S., Fundamenski, W., Garzotti, L., Ghim, Y. C., Gibson, K. J., Gryaznevich, M. P., Harrison, J., Havlickova, E., Hawkes, N. C., Heidbrink, W. W., Hender, T. C., Highcock, E., Higgins, D., Hill, P., Hnat, B., Hole, M. J., Horacek, J., Howell, D. F., Imada, K., Jones, O., Kaveeva, E., Keeling, D., Kirk, A., Kocan, M., Lake, R. J., Lehnen, M., Leggate, H. J., Liang, Y., Lilley, M. K., Lisgo, S. W., Liu, Y. Q., Lloyd, B., Maddison, G. P., Mailloux, J., Martin, R., McArdle, G. J., McClements, K. G., McMillan, B., Michael, C., Militello, F., Molchanov, P., Mordijck, S., Morgan, T., Morris, A. W., Muir, D. G., Nardon, E., Naulin, V., Naylor, G., Nielsen, A. H., O'Brien, M. R., O'Gorman, T., Pamela, S., Parra, F. I., Patel, A., Pinches, S. D., Price, M. N., Roach, C. M., Robinson, J. R., Romanelli, M., Rozhansky, V., Saarelma, S., Sangaroon, S., Saveliev, A., Scannell, R., Seidl, J., Sharapov, S. E., Schekochihin, A. A., Shevchenko, V., Shibaev, S., Stork, D., Storrs, J., Sykes, A., Tallents, G. J., Tamain, P., Taylor, D., Temple, D., Thomas-Davies, N., Thornton, A., Turnyanskiy, M. R., Valovic, M., Vann, R. G. L., Verwichte, E., Voskoboynikov, P., Voss, G., Warder, S. E. V., Wilson, H. R., Wodniak, I., Zoletnik, S., and Zagorski, R.

Abstract

New diagnostic, modelling and plant capability on the Mega Ampere Spherical Tokamak (MAST) have delivered important results in key areas for ITER/DEMO and the upcoming MAST Upgrade, a step towards future ST devices on the path to fusion currently under procurement. Micro-stability analysis of the pedestal highlights the potential roles of micro-tearing modes and kinetic ballooning modes for the pedestal formation. Mitigation of edge localized modes (ELM) using resonant magnetic perturbation has been demonstrated for toroidal mode numbers n = 3, 4, 6 with an ELM frequency increase by up to a factor of 9, compatible with pellet fuelling. The peak heat flux of mitigated and natural ELMs follows the same linear trend with ELM energy loss and the first ELM-resolved T-i measurements in the divertor region are shown. Measurements of flow shear and turbulence dynamics during L-H transitions show filaments erupting from the plasma edge whilst the full flow shear is still present. Off-axis neutral beam injection helps to strongly reduce the redistribution of fast-ions due to fishbone modes when compared to on-axis injection. Low-k ion-scale turbulence has been measured in L-mode and compared to global gyro-kinetic simulations. A statistical analysis of principal turbulence time scales shows them to be of comparable magnitude and reasonably correlated with turbulence decorrelation time. T-e inside the island of a neoclassical tearing mode allow the analysis of the island evolution without assuming specific models for the heat flux. Other results include the discrepancy of the current profile evolution during the current ramp-up with solutions of the poloidal field diffusion equation, studies of the anomalous Doppler resonance compressional Alfven eigenmodes, disruption mitigation studies and modelling of the new divertor design for MAST Upgrade. The novel 3D electron Bernstein synthetic imaging shows promising first data sensitive to the edge current profile and flows.

Published
2013
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2. Overview of physics results from MAST

Author

Lloyd, B., Akers, R. J., Alladio, F., Allan, S., Appel, L. C., Barnes, M., Barratt, N. C., Ben Ayed, N., Breizman, B. N., Cecconello, Marco, Challis, C. D., Chapman, I. T., Ciric, D., Colyer, G., Connor, J. W., Conway, N. J., Cox, M., Cowley, S. C., Cunningham, G., Darke, A., De Bock, M., Delchambre, E., De Temmerman, G., Dendy, R. O., Denner, P., Driscoll, M. D., Dudson, B., Dunai, D., Dunstan, M., Elmore, S., Field, A. R., Fishpool, G., Freethy, S., Garzotti, L., Gibson, K. J., Gryaznevich, M. P., Guttenfelder, W., Harrison, J., Hastie, R. J., Hawkes, N. C., Hender, T. C., Hnat, B., Howell, D. F., Hua, M. -D, Hubbard, A., Huysmans, G., Keeling, D., Kim, Y. C., Kirk, A., Liang, Y., Lilley, M. K., Lisak, M., Lisgo, S., Liu, Y. Q., Maddison, G. P., Maingi, R., Manhood, S. J., Martin, R., McArdle, G. J., McCone, J., Meyer, H., Michael, C., Mordijck, S., Morgan, T., Morris, A. W., Muir, D. G., Nardon, E., Naylor, G., O'Brien, M. R., O'Gorman, T., Palenik, J., Patel, A., Pinches, S. D., Price, M. N., Roach, C. M., Rozhansky, V., Saarelma, S., Sabbagh, S. A., Saveliev, A., Scannell, R., Sharapov, S. E., Shevchenko, V., Shibaev, S., Stork, D., Storrs, J., Suttrop, W., Sykes, A., Tamain, P., Taylor, D., Temple, D., Thomas-Davies, N., Thornton, A., Turnyanskiy, M. R., Valovic, M., Vann, R. G. L., Voss, G., Walsh, M. J., Warder, S. E. V., Wilson, H. R., Windridge, M., Wisse, M., Zoletnik, S., Lloyd, B., Akers, R. J., Alladio, F., Allan, S., Appel, L. C., Barnes, M., Barratt, N. C., Ben Ayed, N., Breizman, B. N., Cecconello, Marco, Challis, C. D., Chapman, I. T., Ciric, D., Colyer, G., Connor, J. W., Conway, N. J., Cox, M., Cowley, S. C., Cunningham, G., Darke, A., De Bock, M., Delchambre, E., De Temmerman, G., Dendy, R. O., Denner, P., Driscoll, M. D., Dudson, B., Dunai, D., Dunstan, M., Elmore, S., Field, A. R., Fishpool, G., Freethy, S., Garzotti, L., Gibson, K. J., Gryaznevich, M. P., Guttenfelder, W., Harrison, J., Hastie, R. J., Hawkes, N. C., Hender, T. C., Hnat, B., Howell, D. F., Hua, M. -D, Hubbard, A., Huysmans, G., Keeling, D., Kim, Y. C., Kirk, A., Liang, Y., Lilley, M. K., Lisak, M., Lisgo, S., Liu, Y. Q., Maddison, G. P., Maingi, R., Manhood, S. J., Martin, R., McArdle, G. J., McCone, J., Meyer, H., Michael, C., Mordijck, S., Morgan, T., Morris, A. W., Muir, D. G., Nardon, E., Naylor, G., O'Brien, M. R., O'Gorman, T., Palenik, J., Patel, A., Pinches, S. D., Price, M. N., Roach, C. M., Rozhansky, V., Saarelma, S., Sabbagh, S. A., Saveliev, A., Scannell, R., Sharapov, S. E., Shevchenko, V., Shibaev, S., Stork, D., Storrs, J., Suttrop, W., Sykes, A., Tamain, P., Taylor, D., Temple, D., Thomas-Davies, N., Thornton, A., Turnyanskiy, M. R., Valovic, M., Vann, R. G. L., Voss, G., Walsh, M. J., Warder, S. E. V., Wilson, H. R., Windridge, M., Wisse, M., and Zoletnik, S.

Abstract

Major developments on the Mega Amp Spherical Tokamak (MAST) have enabled important advances in support of ITER and the physics basis of a spherical tokamak (ST) based component test facility (CTF), as well as providing new insight into underlying tokamak physics. For example, L-H transition studies benefit from high spatial and temporal resolution measurements of pedestal profile evolution (temperature, density and radial electric field) and in support of pedestal stability studies the edge current density profile has been inferred from motional Stark effect measurements. The influence of the q-profile and E x B flow shear on transport has been studied in MAST and equilibrium flow shear has been included in gyro-kinetic codes, improving comparisons with the experimental data. H-modes exhibit a weaker q and stronger collisionality dependence of heat diffusivity than implied by IPB98(gamma, 2) scaling, which may have important implications for the design of an ST-based CTF. ELM mitigation, an important issue for ITER, has been demonstrated by applying resonant magnetic perturbations (RMPs) using both internal and external coils, but full stabilization of type-I ELMs has not been observed. Modelling shows the importance of including the plasma response to the RMP fields. MAST plasmas with q > 1 and weak central magnetic shear regularly exhibit a long-lived saturated ideal internal mode. Measured plasma braking in the presence of this mode compares well with neo-classical toroidal viscosity theory. In support of basic physics understanding, high resolution Thomson scattering measurements are providing new insight into sawtooth crash dynamics and neo-classical tearing mode critical island widths. Retarding field analyser measurements show elevated ion temperatures in the scrape-off layer of L-mode plasmas and, in the presence of type-I ELMs, ions with energy greater than 500 eV are detected 20 cm outside the separatrix. Disruption mitigation by massive gas injection h

Published
2011
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3. Overview of physics results from MAST

Author

Meyer, H., Akers, R. J., Alladio, F., Appel, L. C., Axon, K. B., Ben Ayed, N., Boerner, P., Buttery, R. J., Carolan, P. G., Ciric, D., Challis, C. D., Chapman, I. T., Coyler, G., Connor, J. W., Conway, N. J., Cowley, S., Cox, M., Counsell, G. F., Cunningham, G., Darke, A., deBock, M., deTemmerman, G., Dendy, R. O., Dowling, J., Dnestrovskij, A. Yu, Dnestrovskij, Yu. N., Dudson, B., Dunai, D., Dunstan, M., Field, A. R., Foster, A., Garzotti, L., Gibson, K., Gryaznevich, M. P., Guttenfelder, W., Hawkes, N. C., Harrison, J., Helander, P., Hender, T. C., Hnat, B., Hole, M. J., Howell, D. F., Hua, M. Duc, Hubbard, A., Istenic, M., Joiner, N., Keeling, D., Kirk, A., Koslowski, H. R., Liang, Y., Lilley, M., Lisgo, S., Lloyd, B., Maddison, G. P., Maingi, R., Mancuso, A., Manhood, S. J., Martin, R., McArdle, G. J., McCone, J., Michael, C., Micozzi, P., Morgan, T., Morris, A. W., Muir, D. G., Nardon, E., Naylor, G., O'Brien, M. R., O'Gorman, T., Patel, A., Pinches, S. D., Preinhaelter, J., Price, M. N., Rachlew, Elisabeth, Reiter, D., Roach, C. M., Rozhansky, V., Saarelma, S., Saveliev, A., Scannell, R., Sharapov, S. E., Shevchenko, V., Shibaev, S., Smith, H., Staebler, G. E., Stork, D., Storrs, J., Sykes, A., Tallents, S., Tamain, P., Taylor, D., Temple, D., Thomas-Davies, N., Thornton, A., Thyagaraja, A., Turnyanskiy, M. R., Urban, J., Valovic, M., Vann, R. G. L., Volpe, F., Voss, G., Walsh, M. J., Warder, S. E. V., Watkins, R., Wilson, H. R., Windridge, M., Wisse, M., Zabolotski, A., Zoletnik, S., Zolotukhin, O., Meyer, H., Akers, R. J., Alladio, F., Appel, L. C., Axon, K. B., Ben Ayed, N., Boerner, P., Buttery, R. J., Carolan, P. G., Ciric, D., Challis, C. D., Chapman, I. T., Coyler, G., Connor, J. W., Conway, N. J., Cowley, S., Cox, M., Counsell, G. F., Cunningham, G., Darke, A., deBock, M., deTemmerman, G., Dendy, R. O., Dowling, J., Dnestrovskij, A. Yu, Dnestrovskij, Yu. N., Dudson, B., Dunai, D., Dunstan, M., Field, A. R., Foster, A., Garzotti, L., Gibson, K., Gryaznevich, M. P., Guttenfelder, W., Hawkes, N. C., Harrison, J., Helander, P., Hender, T. C., Hnat, B., Hole, M. J., Howell, D. F., Hua, M. Duc, Hubbard, A., Istenic, M., Joiner, N., Keeling, D., Kirk, A., Koslowski, H. R., Liang, Y., Lilley, M., Lisgo, S., Lloyd, B., Maddison, G. P., Maingi, R., Mancuso, A., Manhood, S. J., Martin, R., McArdle, G. J., McCone, J., Michael, C., Micozzi, P., Morgan, T., Morris, A. W., Muir, D. G., Nardon, E., Naylor, G., O'Brien, M. R., O'Gorman, T., Patel, A., Pinches, S. D., Preinhaelter, J., Price, M. N., Rachlew, Elisabeth, Reiter, D., Roach, C. M., Rozhansky, V., Saarelma, S., Saveliev, A., Scannell, R., Sharapov, S. E., Shevchenko, V., Shibaev, S., Smith, H., Staebler, G. E., Stork, D., Storrs, J., Sykes, A., Tallents, S., Tamain, P., Taylor, D., Temple, D., Thomas-Davies, N., Thornton, A., Thyagaraja, A., Turnyanskiy, M. R., Urban, J., Valovic, M., Vann, R. G. L., Volpe, F., Voss, G., Walsh, M. J., Warder, S. E. V., Watkins, R., Wilson, H. R., Windridge, M., Wisse, M., Zabolotski, A., Zoletnik, S., and Zolotukhin, O.

Abstract

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 (STs). 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 designed total throughput capacity. The anomalous momentum diffusion, chi(phi), is linked to the ion diffusion, chi(i), with a Prandtl number close to P-phi approximate to chi(phi)/chi(i) approximate to 1, although chi(i) approaches neoclassical values. New high spatial resolution measurements of the edge radial electric field, E-r, show that the position of steepest gradients in electron pressure and E-r (i.e. shearing rate) are coincident, but their magnitudes are not linked. The T-e pedestal width on MAST scales with root beta(ped)(pol) rather than rho(pol). The edge localized mode (ELM) frequency for type-IV ELMs, new in MAST, was almost doubled using n = 2 resonant magnetic perturbations from a set of four 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 Alfven eigenmodes. Fast particle instabilities also affect the off-axis NBI current drive, leading to fast ion diffusion of the order of 0.5 m(2) s(-1) and a reduction in the driven current fraction from 40% to 30%. EBW current drive start-up is demonstrated for the first time in a ST generating plasma currents up to 55 kA. Many of these studies contributed to the, QC 20110414

Published
2009
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4. Overview of physics results from MAST

Author

Lloyd, B., Akers, R. J., Alladio, F., Andrew, Y., Appel, L. C., Applegate, D., Axon, K. B., Ben Ayed, N., Bunting, C., Buttery, R. J., Carolan, P. G., Chapman, I., Ciric, D., Connor, J. W., Conway, N. J., Cox, M., Counsell, G. F., Cunningham, G., Darke, A., Delchambre, E., Dendy, R. O., Dowling, J., Dudson, B., Dunstan, M., Field, A. R., Foster, A., Gee, S., Garzotti, L., Gryaznevich, M. P., Gurchenko, A., Gusakov, E., Hawkes, N. C., Helander, P., Hender, T. C., Hnat, B., Howell, D. F., Joiner, N., Keeling, D., Kirk, A., Koch, B., Kuldkepp, Mattias, Lisgo, S., Lott, F., Maddison, G. P., Maingi, R., Mancuso, A., Manhood, S. J., Martin, R., McArdle, G. J., McCone, J., Meyer, H., Micozzi, P., Morris, A. W., Muir, D. G., Nelson, M., O'Brien, M. R., Patel, A., Pinches, S., Preinhaelter, J., Price, M. N., Rachlew, Elisabeth, Roach, C. M., Rozhansky, V., Saarelma, S., Saveliev, A., Scannell, R., Sharapov, S. E., Shevchenko, V., Shibaev, S., Stammers, K., Storrs, J., Surkov, A., Sykes, A., Tallents, S., Taylor, D., Thomas-Davies, N., Turnyanskiy, M. R., Urban, J., Valovic, M., Vann, R. G. L., Volpe, F., Voss, G., Walsh, M. J., Warder, S. E. V., Watkins, R., Wilson, H. R., Wisse, M., Lloyd, B., Akers, R. J., Alladio, F., Andrew, Y., Appel, L. C., Applegate, D., Axon, K. B., Ben Ayed, N., Bunting, C., Buttery, R. J., Carolan, P. G., Chapman, I., Ciric, D., Connor, J. W., Conway, N. J., Cox, M., Counsell, G. F., Cunningham, G., Darke, A., Delchambre, E., Dendy, R. O., Dowling, J., Dudson, B., Dunstan, M., Field, A. R., Foster, A., Gee, S., Garzotti, L., Gryaznevich, M. P., Gurchenko, A., Gusakov, E., Hawkes, N. C., Helander, P., Hender, T. C., Hnat, B., Howell, D. F., Joiner, N., Keeling, D., Kirk, A., Koch, B., Kuldkepp, Mattias, Lisgo, S., Lott, F., Maddison, G. P., Maingi, R., Mancuso, A., Manhood, S. J., Martin, R., McArdle, G. J., McCone, J., Meyer, H., Micozzi, P., Morris, A. W., Muir, D. G., Nelson, M., O'Brien, M. R., Patel, A., Pinches, S., Preinhaelter, J., Price, M. N., Rachlew, Elisabeth, Roach, C. M., Rozhansky, V., Saarelma, S., Saveliev, A., Scannell, R., Sharapov, S. E., Shevchenko, V., Shibaev, S., Stammers, K., Storrs, J., Surkov, A., Sykes, A., Tallents, S., Taylor, D., Thomas-Davies, N., Turnyanskiy, M. R., Urban, J., Valovic, M., Vann, R. G. L., Volpe, F., Voss, G., Walsh, M. J., Warder, S. E. V., Watkins, R., Wilson, H. R., and Wisse, M.

Abstract

Substantial advances have been made on the Mega AmpÚre Spherical Tokamak (MAST). The parameter range of the MAST confinement database has been extended and it now also includes pellet-fuelled discharges. Good pellet retention has been observed in H-mode discharges without triggering an ELM or an H/L transition during peripheral ablation of low speed pellets. Co-ordinated studies on MAST and DIII-D demonstrate a strong link between the aspect ratio and the beta scaling of H-mode energy confinement, consistent with that obtained when MAST data were merged with a subset of the ITPA database. Electron and ion ITBs are readily formed and their evolution has been investigated. Electron and ion thermal diffusivities have been reduced to values close to the ion neoclassical level. Error field correction coils have been used to determine the locked mode threshold scaling which is comparable to that in conventional aspect ratio tokamaks. The impact of plasma rotation on sawteeth has been investigated and the results have been well-modelled using the MISHKA-F code. Alfvén cascades have been observed in discharges with reversed magnetic shear. Measurements during off-axis NBCD and heating are consistent with classical fast ion modelling and indicate efficient heating and significant driven current. Central electron Bernstein wave heating has been observed via the O-X-B mode conversion process in special magnetically compressed plasmas. Plasmas with low pedestal collisionality have been established and further insight has been gained into the characteristics of filamentary structures at the plasma edge. Complex behaviour of the divertor power loading during plasma disruptions has been revealed by high resolution infra-red measurements., QC 20110414 ISI anger titeln som "Overview MAST" Har ingått i: 21st IAEA Fusion Energy Conference, Chengdu, PEOPLES R CHINA, OCT 16-21, 2006

Published
2007
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6. MAST and the impact of low aspect ratio on tokamak physics

Author

Lloyd, B, primary, Ahn, J-W, additional, Akers, R J, additional, Appel, L C, additional, Applegate, D, additional, Axon, K B, additional, Baranov, Y, additional, Brickley, C, additional, Bunting, C, additional, Buttery, R J, additional, Carolan, P G, additional, Challis, C, additional, Ciric, D, additional, Conway, N J, additional, Cox, M, additional, Counsell, G F, additional, Cunningham, G, additional, Darke, A, additional, Dnestrovskij, A, additional, Dowling, J, additional, Dudson, B, additional, Dunstan, M R, additional, Field, A R, additional, Gee, S, additional, Gryaznevich, M P, additional, Helander, P, additional, Hender, T C, additional, Hole, M, additional, Joiner, N, additional, Keeling, D, additional, Kirk, A, additional, Lehane, I P, additional, Lott, F, additional, Maddison, G P, additional, Manhood, S J, additional, Martin, R, additional, McArdle, G J, additional, McClements, K G, additional, Meyer, H, additional, Morris, A W, additional, Nelson, M, additional, O'Brien, M R, additional, Patel, A, additional, Pinfold, T, additional, Preinhaelter, J, additional, Price, M N, additional, Roach, C M, additional, Rozhansky, V, additional, Saarelma, S, additional, Saveliev, A, additional, Scannell, R, additional, Sharapov, S, additional, Shevchenko, V, additional, Shibaev, S, additional, Stammers, K, additional, Storrs, J, additional, Sykes, A, additional, Tabasso, A, additional, Taylor, D, additional, Tournianski, M R, additional, Turner, A, additional, Turri, G, additional, Valovic, M, additional, Volpe, F, additional, Voss, G, additional, Walsh, M J, additional, Watkins, J R, additional, Wilson, H R, additional, Wisse, M, additional, and Teams, the MAST, NBI and ECRH, additional

Published
2004
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7. Transport and confinement in the Mega Ampère Spherical Tokamak (MAST) plasma

Author

Akers, R J, primary, Ahn, J W, additional, Antar, G Y, additional, Appel, L C, additional, Applegate, D, additional, Brickley, C, additional, Bunting, C, additional, Carolan, P G, additional, Challis, C D, additional, Conway, N J, additional, Counsell, G F, additional, Dendy, R O, additional, Dudson, B, additional, Field, A R, additional, Kirk, A, additional, Lloyd, B, additional, Meyer, H F, additional, Morris, A W, additional, Patel, A, additional, Roach, C M, additional, Rohzansky, V, additional, Sykes, A, additional, Taylor, D, additional, Tournianski, M R, additional, Valovic, M, additional, Wilson, H R, additional, Axon, K B, additional, Buttery, R J, additional, Ciric, D, additional, Cunningham, G, additional, Dowling, J, additional, Dunstan, M R, additional, Gee, S J, additional, Gryaznevich, M P, additional, Helander, P, additional, Keeling, D L, additional, Knight, P J, additional, Lott, F, additional, Loughlin, M J, additional, Manhood, S J, additional, Martin, R, additional, McArdle, G J, additional, Price, M N, additional, Stammers, K, additional, Storrs, J, additional, Walsh, M J, additional, and Team, the MAST and NBI, additional

Published
2003
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8. Overview of recent experimental results on MAST

Author

Lloyd, B., Ahn, J. W., Akers, R. J., Appel, L. C., Arends, E. R., Axon, K. B., Buttery, R. J., Byrom, C., Carolan, P. G., Challis, C., Ciric, D., Conway, N. J., Cox, M., Counsell, G. F., Cunningham, G., Darke, A., Dnestrovskij, A., Dowling, J., Dunstan, M. R., Field, A. R., Fielding, S. J., Gee, S., Gryaznevich, M. P., Helander, P., Hole, M., Hood, M. B., Jones, P. A., Kirk, A., Lehane, I. P., Maddison, G. P., Manhood, S. J., Martin, R., McArdle, G. J., McClements, K. G., McGrath, M. A., Meyer, H., Morris, A. W., Nielsen, S. K., Nightingale, M., Patel, A., Pinfold, T., Price, M. N., Qin, J., Ribeiro, C., Roach, C. M., Robinson, D. C., Sauter, O., Shevchenko, V., Shibaev, S., Stammers, K., Sykes, A., Tabasso, A., Taylor, D., Tournianski, M. R., Turri, G., Valovic, M., Voss, G., Walsh, M. J., Warder, S., Watkins, J. R., Wilson, H. R., Yang, Y., and You, S.

Subjects
Physics::Plasma Physics
Abstract

The low aspect ratio of the mega amp spherical tokamak (MAST) allows differentiation between different forms of the H-mode threshold scaling. With optimized fuelling using inboard puffing, and a connected double null divertor (DND) magnetic configuration, the H-mode power threshold data lie about 1.7 times higher than recent scaling laws. Slight magnetic configuration changes, of the order of the ion Larmor radius, around a connected DND significantly influence H-mode access. H-mode confinement in discharges with low frequency edge localized modes (ELMs) is generally consistent with international scaling laws, e.g. IPB98(y,2). Strong indications of both particle and energy internal transport barriers have been seen. Normalized beta values beta(N) > 5 have been obtained, approaching the ideal n = I no wall external kink stability limit. Sawtooth triggered neo-classical tearing modes have been observed; numerical modelling of the island evolution reproduces mode behaviour well and confirms the significance of stabilizing field curvature effects. Divertor power loading studies, including transient effects due to ELMs, show a strong bias of power efflux to the outboard targets, where it is more easily handled. ELM energy losses, DeltaW(ELM), are less than 4% of the stored energy in all regimes explored so far, but ELM effluxes extending 30 cm outside the outboard separatrix have been measured. Toroidally asymmetric divertor biasing resulted in significant broadening of the D-alpha profile on the biased components and a reduction in the total power to the unbiased components. Halo current magnitudes and asymmetries are generally small compared with conventional tokamaks; recent measurements show that the plasma behaves more as a voltage source than a current source. Initial neutral beam current drive experiments indicate non-inductively driven current values (I-NBI similar to 0.3I(p)) comparable with code predictions.

9. A field programmable gate array unit for the diagnosis and control of neoclassical tearing modes on MAST.

Author

O'Gorman, T., Naylor, G., Gibson, K. J., Huang, B., McArdle, G. J., Scannell, R., Shibaev, S., Snape, J. A., and Thomas-Davies, N.

Subjects
FIELD programmable gate arrays, PLASMA diagnostics, TOKAMAKS, THOMSON scattering, PLASMA confinement, TOROIDAL plasma
Abstract

A real-time system has been developed to trigger both the MAST Thomson scattering (TS) system and the plasma control system on the phase and amplitude of neoclassical tearing modes (NTMs), extending the capabilities of the original system. This triggering system determines the phase and amplitude of a given NTM using magnetic coils at different toroidal locations. Real-time processing of the raw magnetic data occurs on a low cost field programmable gate array (FPGA) based unit which permits triggering of the TS lasers on specific amplitudes and phases of NTM evolution. The MAST plasma control system can receive a separate trigger from the FPGA unit that initiates a vertical shift of the MAST magnetic axis. Such shifts have fully removed m/n = 2/1 NTMs instabilities on a number of MAST discharges. [ABSTRACT FROM AUTHOR]

Published
2012
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