UKAEA Journals

Showing 1 - 8 of 8 Journals Results
2021
UKAEA-CCFE-PR(21)09

Ion cyclotron emission (ICE) driven by perpendicular neutral beam-injected (NBI) deuterons, together with the distinctive ICE driven by tangential NBI, have been observed from heliotron-stellarator plasmas in the Large Helical Device (LHD). Radio frequency radiation in the lower hybrid range has also been observed, with frequency dependent on plasm…

Preprint
2020
UKAEA-CCFE-PR(21)48

During bursty MHD events, transient ion cyclotron emission (ICE) is observed from deuterium plasmas in the Large Helical Device (LHD) heliotron-stellarator. Unusually, the frequencies of the successive ICE spectral peaks are not close to integer multiples of the local cyclotron frequency of an energetic ion population in the likely emitting region.…

Preprint
2020
UKAEA-CCFE-PR(20)101

A method to quantify the energy transfer among turbulent structures using singular value decomposition (SVD) is presented. We apply the method to numerical turbulence data obtained from a global plasma simulation using the Hasegawa-Wakatani fluid model, in which the Kelvin-Helmholtz instability plays a dominant role. Using the SVD method, …

Preprint Purchase
The published version of this paper is currently under embargo and will be available on 08/12/2021
2019
UKAEA-CCFE-PR(19)32

The novel technique of dynamical mode decomposition (DMD) is applied to the outputs of a numerical simulation of Kelvin-Helmholtz turbulence in a cylindical plasma, so as to capture and quantify the time evolution of the dominant nonlinear structures. These structures comprise rotationally symmetric deformations together with spiral patterns, which…

Preprint Published
2019
UKAEA-CCFE-PR(19)24

Ion cyclotron emission (ICE) is detected from all large toroidal magnetically conned fusion (MCF) plasmas. It is a form of spontaneous suprathermal radiation, whose spectral peak frequencies correspond to sequential cyclotron harmonics of energetic ion species, evaluated at the emission location. We first present an account of the worldwide exper…

Preprint Published
2015
CCFE-PR(15)64

It is known that rapid edge cooling of magnetically confined plasmas can trigger heat pulses that propagate rapidly inward. These can result in large excursion, either positive or negative, in the electron temperature at the core. A set of particularly detailed measurements was obtained in Large Helical Device(LHD) plasmas [S. Inagaki et al, Plasma…

Preprint Published
2013

In some magnetically confined plasmas, an applied pulse of rapid edge cooling can trigger either a positive or negative excursion in the core electron temperature from its steady state value. We present a new model which captures the time evolution of the transient, non-diffusive local dynamics in the core plasma. We show quantitative agreement bet…

Published
2009

Several types of microwave diagnostics, in the category of electron cyclotron emission (ECE) spectroscopy and reflectometry, have been developed on the Large Helical Device (LHD). Since LHD has a complicated magnetic configuration, the polarization effects have been studied for optimization of the microwave passive and active diagnostics. It was fo…

Published