6 research outputs found
Implementation of synthetic fast-ion loss detector and imaging heavy ion beam probe diagnostics in the 3D hybrid kinetic-MHD code MEGA
A synthetic fast-ion loss (FIL) detector and an imaging Heavy Ion Beam Probe (i-HIBP) have been implemented in the 3D hybrid kinetic-magnetohydrodynamic code MEGA. First synthetic measurements from these two diagnostics have been obtained for neutral beam injection-driven Alfvén Eigenmode (AE) simulated with MEGA. The synthetic FILs show a strong correlation with the AE amplitude. This correlation is observed in the phase-space, represented in coordinates (Pϕ, E), being toroidal canonical momentum and energy, respectively. FILs and the energy exchange diagrams of the confined population are connected with lines of constant E′, a linear combination of E and Pϕ. First i-HIBP synthetic signals also have been computed for the simulated AE, showing displacements in the strike line of the order of ∼1 mm, above the expected resolution in the i-HIBP scintillator of ∼100 μm.European Starting Grant (ERC) from project 3D-FIREFLUCSpanish Ministry of Science under Grant No. FPU19/02267EUROfusion Consortium grant agreement No 63305
Modelling of the interaction between ELMs and fast-ions using MEGA
EUROfusion Consortium 63305
Non-linear hybrid kinetic-MHD simulations of ELMs in the ASDEX Upgrade tokamak
EUROfusion Consortium 63305
Kinetic Modelling of ELM-induced Fast-ion Transport and Acceleration in the ASDEX Upgrade Tokamak
Universidad de Sevilla PP2016-7145EUROfusion Consortium 63305
Dependence on plasma shape and plasma fueling for small ELM regimes in TCV and ASDEX Upgrade
Within the EUROfusion MST1 Work Package, a series of experiments
has been conducted on AUG and TCV devices to disentangle the role of plasma
fueling and plasma shape for the onset of small ELM regimes. On both devices, small
ELM regimes with high confinement are achieved if and only if two conditions are
fulfilled at the same time. Firstly, the plasma density at the separatrix must be large enough (ne,sep/nG ∼ 0.3), leading to a pressure profile flattening at the separatrix, which stabilizes type-I ELMs. Secondly, the magnetic configuration has to be close to a Double Null (DN), leading to a reduction of the magnetic shear in the extreme vicinity of the separatrix. As a consequence, its stabilizing effect on ballooning modes is weakened.EURATOM 63305
Transport and acceleration mechanism of fast ions during edge localized modes in ASDEX Upgrade
Original Content from this work may be used under the
terms of the Creative Commons Attribution 4.0 licence. Any
further distribution of this work must maintain attribution to the author(s) and
the title of the work, journal citation and DOI.Observations of enhanced fast-ion losses during edge localized modes (ELMs) have been reported in the ASDEX Upgrade tokamak, revealing losses above the injection energy. This suggests that fast ions can be accelerated and lost due to the ELMs. Recent analysis of the ELM-induced losses suggests that the fast ions are lost due to a resonant interaction with the electromagnetic perturbation during the ELM crash. The fast-ion transport and acceleration during ELMs is modelled using electromagnetic fields computed using the hybrid kinetic-MHD code MEGA, while fast-ion full orbits are tracked with the ASCOT code. Time-evolving 3D electromagnetic fields have been implemented in ASCOT to compute fast-ion orbits in the presence of fast MHD events such as ELMs. The simulations successfully reproduce a field-aligned pattern of the losses on the tokamak wall and the formation of an accelerated population in the lost fast-ion distribution, while they predict an accelerated population in the confined distribution. A parametric study of the fast-ion constants of motion suggests a resonant interaction between the fast-ions and the electromagnetic fields arising during the ELM crash. In the case of fast-ion acceleration, the perpendicular electric perturbation, with scales smaller than the fast-ion gyroradius, breaks magnetic moment conservation and resonantly modifies the fast-ion energy