T. O’Gorman P. J. Mc Carthy S. Prunty M. J. Walsh M. R. Dunstan R. B. Huxford G. Naylor Emmanuel Maguet R. Scannell S. Shibaev
A major upgrade to the ruby Thomson scattering (TS) system has been designed and implemented on the Mega-ampere spherical tokamak (MAST). MAST is equipped with two TS systems, a Nd:YAG laser system and a ruby laser system. Apart from common collection optics each system provides independent measurements of the electron temperature and density profi…
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. 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…
PublishedN. J. Conway
A motional Stark effect MSE diagnostic is now installed and operating routinely on the MAST spherical tokamak, with 35 radial channels, spatial resolution of 2.5 cm, and time resolution of 1 ms at angular noise levels of 0.5°. Conventional albeit very narrow interference filters isolate or polarized emission. Avalanche photodiode detectors with di…
PublishedYoung-Chul Ghim(Kim) A. R. Field S. Zoletnik D. Dunai
The beam emission spectroscopy BES turbulence diagnostic on MAST is to be upgraded in June 2010 from a one-dimensional trial system to a two-dimensional imaging system 8 radial 4 poloidal channels based on a newly developed avalanche photodiode array camera. The spatial resolution of the new system is calculated in terms of the point spread functio…
PublishedJ. Figueiredo G. Naylor M. Walsh M. Dunstan R. Scannell F. Serra
The recent upgrade to the MAST YAG Thomson scattering while enhancing the diagnostic capabilities increased the complexity of the system. There are eight YAG lasers now operational, doubling the number from the previous setup. This means alignment between each laser individually and reference points is essential to guarantee data quality and diagno…
PublishedR. Scannell M. J. Walsh M. R. Dunstan J. Figueiredo G. Naylor T. O’Gorman K. J. Gibson H. Wilson S. Shibaev
A Thomson scattering diagnostic designed to measure both edge and core physics has been implemented on MAST. The system uses eight Nd:YAG lasers, each with a repetition rate of 30 Hz. The relative and absolute timing of the lasers may be set arbitrarily to produce fast bursts of measurements to suit the time evolution of the physics being studied. …
PublishedM. Cecconello M. Turnyanskiy S. Conroy G. Ericsson E. Ronchi S. Sangaroon R. Akers I. Fitzgerald A. Cullen M. Weiszflog
A prototype neutron camera has been developed and installed at MAST as part of a feasibility study for a multichord neutron camera system with the aim to measure the spatial and time resolved 2.45 MeV neutron emissivity profile. Liquid scintillators coupled to a fast digitizer are used for neutron/ gamma ray digital pulse shape discrimination. The …
PublishedD. Dunai S. Zoletnik J. Sárközi A.R. Field
An avalanche photodiode based APD detector for the visible wavelength range was developed for low light level, high frequency beam emission spectroscopy BES experiments in fusion plasmas. This solid state detector has higher quantum efficiency than photomultiplier tubes, and unlike normal photodiodes, it has internal gain. This paper describes the …
PublishedG. De Temmerman E. Delchambre A. Kirk S. Lisgo P. Tamain
A long wavelength range infrared camera (LWIR) has been installed on MAST to compliment the existing medium wave infrared system. Simultaneous LWIR/MWIR temperature measurements have been made in the lower and upper divertors of MAST. As expected, the LWIR system is less sensitive to disturbances from hot spots on the surface. A thorough correction…
Published