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Title: Overview of physics results from MAST

Journal Article · · Nuclear Fusion
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  1. EURATOM CCFE Fus Assoc, Culham Sci Ctr, Abingdon, Oxon, England
  2. Assoc EURATOM ENEA Fus. Rome, Italy
  3. Univ. York, Dept. Phys. York YO10 5DD, N Yorkshire, England
  4. University of Texas, Austin
  5. Uppsala Univ., EURATOM VR Assoc., SE-75120 Uppsala, Sweden
  6. Assoc. Euratom CEA, CEA Cadarache, F-13108, St. Paul Les Durance, France
  7. EURATOM, KFKI RMKI, H-1525 Budapest, Hungary
  8. Univ. Liverpool, Dept. Elect. Engn. & Elect., Liverpool L69 3BX, Merseyside, England
  9. EURATOM, Culham Sci Ctr, Abingdon, Oxon England
  10. Univ. Warwick, Dept. Phys. Ctr. Fus. Space & Astrophys., Coventry CV4 7AL, W. Midlands, England
  11. Univ. London Imperial Coll. Sci. Technol. & Med., London, England
  12. MIT Plasma Sci. & Fus. Ctr, Cambridge, MA 02139 USA
  13. Univ. Oxford, Rudolph Peierls Ctr. Theoret. Phys., Oxford, England
  14. Assoc. Euratom FZ Julich, D-52425, Julich, Germany
  15. Chalmers, S-41296, Gothenburg, Sweden
+ Show Author Affiliations

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 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(y,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 has reduced divertor heat loads by up to 70%.

Research Organization:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Organization:
USDOE Office of Science (SC)
DOE Contract Number:
DE-AC05-00OR22725
OSTI ID:
1036621
Journal Information:
Nuclear Fusion, Vol. 51, Issue 9; ISSN 0029--5515
Country of Publication:
United States
Language:
English

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