UKAEA Journals

Showing 1 - 10 of 52 Journals Results
2021
UKAEA-CCFE-PR(21)78

Alfvén eigenmode (AE) instabilities driven by alpha-particles have been observed in D-3He fusion experiments on the Joint European Torus (JET) with the ITER-like wall (ILW). For the efficient generation of fusion alpha-particles from D-3He fusion reaction, the 3‑ion radio frequency (RF) scenario was used t…

Preprint Published
2021
UKAEA-CCFE-PR(21)36

The interaction of Alfvén Eigenmodes (AEs) and energetic particles will determine the success of future tokamaks. In JET, eight in-vessel antennas were installed to actively probe stable AEs with frequencies ranging 25 – 250 kHz and toroidal mode numbers |n| < 20. During the 2019-2020 deuterium  campaign, almost 7500 resonances and …

Preprint
2021
UKAEA-CCFE-PR(21)30

Recent JET Deuterium experiments with an advanced internal transport barrier (ITB) scenario have been performed to clearly observe destabilised toroidicity-induced Alfvén eigenmodes (TAEs) by fast ions; interestingly, these also exhibit unstable electromagnetic (EM) perturbations in the sub-TAE frequency range. We identify such EM perturbations to…

Preprint Published
2021
UKAEA-CCFE-PR(21)21

In this work, we use reduced and perturbative models to examine the stability of TAEs during the ITB afterglow in JET experiments designed for the observation of alpha driven TAEs.  We demonstrate that in JET-like conditions, it is sufficient to use an incompressible cold plasma model for the TAE to reproduce the experimental adiabatic features su…

Preprint
2020
UKAEA-CCFE-PR(20)131

This paper presents a dedicated study of plasma-antenna (PA) coupling with the Alfvén Eigenmode Active Diagnostic (AEAD) in JET. Stable AEs and their resonant frequencies f, damping rates < 0, and toroidal mode numbers n are measured for various PA separations and limiter versus X-point magnetic cofigurations. Two stable AEs are observed to be …

Preprint Purchase
2020
UKAEA-CCFE-PR(20)100

Dedicated experiments to generate high-energy D ions and D-3He fusion-born alpha particles have been performed at the Joint European Torus (JET) with the ITER-like wall (ILW). Deuterium ions from neutral beam injection (NBI) with acceleration voltage of 100 keV were accelerated to higher energies in the core of mixed D-3He…

Preprint Published
2020
UKAEA-CCFE-PR(20)93

Parametric dependencies of the linear stability of toroidal Alfven eigenmode (TAE) in the presence of neutral beam injection (NBI) are investigated to understand the beam drive and damping effect of TAEs in JET and KSTAR. It is found that the results depend on the drift orbit width of the beam-ions normalized to the characteristic mode widths. I…

Preprint Published
2018
UKAEA-CCFE-PR(20)75

The Gyrokinetic Toroidal Code (GTC) has been used to study Toroidal Alfven Eigenmodes (TAEs) in high-performance plasmas. Experiments performed at the Joint European Torus, where TAEs were driven by energetic particles arising from Neutral Beams, ion cyclotron resonant heating and resonantly excited by dedicated external antennas, have been simulat…

Preprint Published
2019
UKAEA-CCFE-PR(19)65

Alfven frequency sweeping modes in stellarator plasmas with normal and reversed shear rotational transform are modelled using a reduced MHD model. We focus on a TJ-II dynamic discharge in which a sequence of frequency sweeping modes with a frequency sweeping range from 20 kHz to 140 kHz (Melnikov A.V. et al 2014 Nucl. Fusion 54 123002) have been ob…

Preprint Published
2019
UKAEA-CCFE-PR(19)60

Toroidal Alfven Eigenmode (TAE) excitation can be caused by fusion-born or Ion Cyclotron Resonance and neutral beam heating fast particles through wave-particle resonance. TAEs may affect fast particle confinement, reduce heating and current drive efficiency, cause damage to the first wall, and decrease overall plasma performance. Excitation of TA…

Preprint Published