-
UKAEA-CCFE-PR(19)052018
HALO (HAgis LOcust) solves the initial value Vlasov-Maxwell problem perturbatively for application to certain nonlinear wave-particle problems in tokamak plasmas. It uses the same basic approach as the HAGIS code (Pinches et al., 1998) for wave evolution but is built on the LOCUST-GPU full-orbit code (Akers et al., 2012) for the solution of the Ham…
-
UKAEA-CCFE-PR(18)732018
Alfven Eigenmodes were studied in low magnetic shear flexible heliac TJ-II (B0=0.95 T, =1.5 m, =0.22 m) NBI heated plasmas (PNBI <1.1 MW, ENBI=32 keV) by Heavy Ion Beam Probe (HIBP) [1, 2, 3]. The L-mode hydrogen plasma was investigated at various magnetic configurations with rotational transform t(a)/2
-
UKAEA-CCFE-PR(18)472018
The Gyrokinetic Toroidal Code (GTC) has been used to study Toroidal Alfvén 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 simula…
-
UKAEA-CCFE-PR(18)282018
Fishbones are ubiquitous in high-performance JET plasmas and are typically considered to be unimportant for scenario design. However, during recent high-performance hybrid experiments, sporadic and explosive fishbones have been observed which correlate with a reduction in performance and main chamber hotspots. Clear evidence has been obtained of fu…
-
UKAEA-CCFE-PR(18)122018
Alfvén Eigenmodes (AEs) are routinely seen in present-day tokamaks and stellarators with energetic particles and they represent an attractive form of MHD spectroscopy that provides valuable information on background plasma and on the energetic particles. Possible use of AEs is assessed for MHD spectroscopy of plasma with high-velocity pellet injec…
-
CCFE-PR(17)762017
During development of a high-performance hybrid scenario for future deuterium–tritium experiments on the Joint European Torus, an increased level of fast ion losses in the MeV energy range was observed during the instability of high-frequency n = 1 fishbones. The fishbones are excited during deuterium neutral beam injection combined with…
-
CCFE-PR(17)542017
A nonlinear bump-on-tail model for the growth and saturation of energetic particle driven plasma waves has been extended to include two populations of fast particles - one dominated by dynamical friction at the resonance and the other by velocity space diffusion. The resulting temporal evolution of the wave amplitude and frequency depends on the re…
-
CCFE-PR(16)122016
We use the HAGIS code to compute the nonlinear stability of the Q=10 ITER baseline scenario to toroidal Alfveneigenmodes (TAE) and the subsequent effects of these modes on fusion alpha-particle redistribution. Our calculations build upon an earlier linear stability survey [Rodrigues, P. et al. (2015). Nuclear Fusion, 55(8), 083003] which provides a…
-
CCFE-PR(15)502015
The results of a comprehensive investigation into the effects of toroidicity- induced Alfven eigenmodes (TAE) and energetic particle modes on the NBI-generated fast-ion population in MAST plasmas are reported. Fast-ion redistribution due to frequency-chirping TAE in the range 50 kHz to 100 kHz, and frequency-chirping energetic particle modes known …
-
2014
On MAST, compressional Alfven eigenmodes can be destabilized by the presence of a sufficiently large population of energetic particles in the plasma. This dependence was studied in a series of very similar discharges in which increasing amounts of hydrogen were puffed into a deuterium plasma. A simple method to estimate the isotopic ratio nH/nD usi…
Showing 41 - 50 of 80 UKAEA Paper Results