3D simulations of gas puff effects on edge plasma and ICRF coupling in JET

Recent JET (ITER-Like Wall) experiments have shown that the fueling gas puffed from different locations of the vessel can result in different scrape-off layer (SOL) density profiles and therefore different radio frequency (RF) coupling. To reproduce the experimental observations, to understand the associated physics and to optimize the gas puff methods, we have carried out three-dimensional (3D) simulations with the EMC3-EIRENE code in JET-ILW including a realistic description of the vessel geometry and the gas injection modules (GIMs) configuration. Various gas puffing methods have been investigated, in which the location of gas fueling is the only variable parameter. The simulation results are in quantitative agreement with the experimental measurements. They confirm that compared to divertor gas fueling, mid-plane gas puffing increases the SOL density most significantly but locally, while top gas puffing increases it uniformly in toroidal direction but to a lower degree. Moreover, the present analysis corroborates the experimental findings that combined gas puff scenarios-based on distributed main chamber gas puffing-can be effective in increasing the RF coupling for multiple antennas simultaneously. The results indicate that the spreading of the gas, the local ionization and the transport of the ionized gas along the magnetic field lines connecting the local gas cloud in front of the GIMs to the antennas are responsible for the enhanced SOL density and thus the larger RF coupling

Verification/validation and physics model extension in high fidelity 3D RF full wave simulations on Petra-M

This paper reports the recent progress towards a whole-device scale RF actuator simulation. Our approach is to combine progresses made by open source scientific and math software communities for meshing, FEM assembly, and linear solvers to construct an integrated FEM fullwave simulation framework (the Petra-M FEM framework). The goal is to bring in engineering CAD level geometrical detail to our wave simulation capability, and advanced RF wave physics models, such as RF rectified sheath models and non-local hot plasma effects. In Petra-M, the high harmonic fast wave (HHFW) propagation was fully resolved in a 3D NSTX-U torus. In the NSTX-U simulation, the ratio between wavelength to the device size reaches 15, which is in the range required for resolving the ICRF wave fields in ITER. Verification and validation of the RF wave field computed by Petra-M through the international/multi-institutional efforts has been a major research focus, which yields an excellent code benchmark agreement between Petra-M, TOPICA and RAPLCIASOL. The spectral analysis of 3D wave field has been performed to interrogate the wave field behavior, which shows the consistency with the wave theory. RF rectified potential model was incorporated in our wave field solver. We developed a new non-linear iteration algorithm, which allows for using both the thick sheath (asymptotic) model and non-linear sheath impedance models seamlessly. The 3D RF sheath simulation on the WEST ICRF antenna indicates that the sheath potential tends to concentrate near the corner of antenna box, which is consistent with experimental observation of RF induced heat load pattern

Core plasma ion cyclotron emission driven by fusion-born ions

Ion cyclotron emission (ICE) signals whose spectral peaks match the fundamental cyclotron frequencies of hydrogen and tritium in the plasma core, near the magnetic axis, are observed in ASDEX Upgrade deuterium plasmas. In these cases the only source of energetic (1 MeV) hydrogen and tritium ions is D-D fusion reactions between neutral beam injected deuterium ions and bulk deuterium ions. Hydrogen-matched core ICE is observed in a wide variety of ASDEX Upgrade plasmas, while tritium-matched core ICE is (so far) only observed in so-called H-mode density limit plasmas. In all cases ICE signals are detected directly using B-dot probes, which provide information on the emission frequency, the amplitude, and, in principle, the parallel wavenumber values. These observations support the idea of using an ICE-based diagnostic to monitor the presence of fusion-born alpha particles in tritium-burning fusion plasmas on devices such as JET, ITER, CFETR, or DEMO.Comunidad Europea de la Energía Atómica (EURATOM) 63305

Stabilization of microturbulence by fast ions n ASDEX upgrade

The goal of the present work is to study the impact of fast ions, generated by ICRH, on microturbulence. Our methodology is similar to that in [2] and is based on extensive simulations of discharges carried out on the ASDEX Upgrade (AUG) tokamak, in Germany using state-of-art fusion simulations codes

An expert opinion paper on statin adherence and implementation of new lipid-lowering medications by the ESC Working Group on Cardiovascular Pharmacotherapy: Barriers to be overcome.

Benefits and safety on statins have been well-established over 20 years of research. Despite this, the vast majority of patients are not adequately treated and do not achieve the low-density lipoprotein cholesterol target levels. This is mainly due to poor adherence, which is associated with dangerous and sometimes fatal outcomes. To increase adherence and prevent worse outcomes, a combination therapy with lower dosage of statins and new lipid-lowering drugs may be used. However, the implementation of new lipid-lowering drugs in European countries is still at the beginning. For these reasons, the aim of this position paper is to give an up-to-date indication from the ESC Working Group on Cardiovascular Pharmacotherapy in order to discuss the barriers towards statins adherence and new lipid-lowering drugs implementation in Europe