T. Wilson S.J. Freethy M. Henderson A Köhn-Seeman I. Konoplev S. Saarelma D. Speirs R.G.L. Vann the STEP team
The UK’s Spherical Tokamak for Energy Production (STEP) reactor design program is now exclusively investigating concepts using microwave-based heating and current drive (HCD) systems. Electron Bernstein Wave (EBW) HCD is a relatively immature technology compared to Electron Cyclotron (EC) HCD but is of interest due to the promise of high current…
PreprintS. H. Ward R. Akers S. D. Pinches A. Loarte R. G. L. Vann M. A. Van Zeeland L. Li Y. Liu A. Polevoi
The LOCUST GPU code has been applied to study the fast-ion transport caused by resonant magnetic perturbations in the high-performance Q = 10 ITER baseline scenario. The computational speed of the code is used calculate the impact of the ITER ELM-control-coil system on neutral beam heating efficiency, as well as producing detailed predictions o…
Preprint PublishedS. H. Ward R. Akers A. Jacobsen P. Ollus S. D. Pinches E. Tholerus R. G. L. Vann M. A. Van Zeeland
A novel high-performance computing algorithm, developed in response to the next generation of computational challenges associated with burning plasma regimes in ITER-scale tokamak devices, has been tested and is described herein. LOCUST-GPU 2 The Lorentz-Orbit Code for Use in Stellarators and Tokamaks (LOCUST) is designed for computationally scal…
Preprint PublishedK.G. McClements J. Allen S.C. Chapman R.O. Dendy S.W.A. Irvine O. Marshall D. Robb M. Turnyanskiy R.G.L. Vann
The merging-compression method of plasma start-up in the Mega Amp Spherical Tokamak (MAST) involved the creation of two plasma tori with parallel currents, which merged at the vacuum vessel midplane due to their mutual attraction. Magnetic reconnection occurred in this process causing strong heating of both ions and electrons on millisecond timesca…
Preprint PublishedE.J. du Toit M.R. O'Brien R.G.L. Vann
Tokamak plasma current start-up assisted by Electron Bernstein waves (EBW) has been demonstrated successfully in a number of experiments. The dynamic start-up phase involves a change in field topology, as the initially open magnetic field lines form closed flux surfaces (CFS) under the initiation of a plasma current. This change in field topology w…
PreprintD. A. Thomas K. J. Brunner S. J. Freethy B. K. Huang V. F. Shevchenko R. G. L. Vann
The Synthetic Aperture Microwave Imaging (SAMI) diagnostic has conducted proof-of-principle 2D Doppler backscattering (DBS) experiments on MAST. SAMI actively probes the plasma edge using a wide ( 40° vertical and horizontal) and tuneable (10-35.5 GHz) beam. The Doppler backscattered signal is digitised in vector form using an array of eight Vival…
Preprint PublishedS. J. Freethy K. G. McClements S. C. Chapman R. O. Dendy W. N. Lai S. J. P. Pamela V. F. Shevchenko R. G. L. Vann
Recent measurements of microwave and x-ray emission during edge localized mode (ELM) activity in tokamak plasmas provide a fresh perspective on ELM physics. It is evident that electron kinetics, which are not incorporated in standard (fluid) models for the instability that drives ELMs, play a key role in the new observations. These effects should b…
Preprint PublishedVladimir F. Shevchenko Simon J. Freethy Billy K. Huang Roddy G. L. Vann
A Synthetic Aperture Microwave Imaging (SAMI) system has been designed and built to obtain 2-D images at several frequencies from fusion plasmas. SAMI uses a phased array of linearly polarised antennas. The array configuration has been optimised to achieve maximum synthetic aperture beam efficiency. The signals received by antennas are down-convert…
PublishedS.J. Freethy B.K. Huang V.F. Shevchenko R.G.L. Vann
A novel microwave imaging system (SAMI) which utilises an array of phase sensitive antennas to synthesize an optical aperture has been designed and deployed on MAST. The system requires no optical components for focussing and yet is able to image up to half of the plasma surface simultaneously. All image formation is done in post processing and SAM…
PublishedV. F. Shevchenko M. De Bock S. J. Freethy A. N. Saveliev R. G. L. Vann
Angular scanning of electron Bernstein wave emission (EBE) has been conducted in MAST. From EBE measurements over a range of viewing angles, the angular position and orientation of the B-X-O mode conversion (MC) window can be estimated, giving the pitch angle of the magnetic field in the MC layer. The radial position of the corresponding MC layer i…
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