UKAEA Journals

Showing 1 - 10 of 11 Journals Results
2021
UKAEA-CCFE-PR(21)19

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 s…

Preprint
2017
CCFE-PR(17)56

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 Published
2017
CCFE-PR(17)46

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…

Preprint
2015
CCFE-PR(15)72

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 Published
2015
CCFE-PR(15)106

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 Published
2014

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…

Published
2013

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…

Published
2011

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…

Published
2005

Frequency sweeping (chirping) of high frequency magnetohydrodynamic modes is widely observed in tokamak plasmas. In this paper observations of chirping in neutral-beam-heated plasmas in the Mega-Amp Spherical Tokamak (MAST) [A. Sykes, R. J. Akers, L. C. Appel and et al. , Nucl. Fusion 41 , 1423 (2001)] are considered, and it is shown that these may…

Published