| 1. |
- Huynh, P., et al.
(författare)
-
European transport simulator modeling of JET-ILW baseline plasmas: predictive code validation and DTE2 predictions
- 2021
-
Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 61:9
-
Tidskriftsartikel (refereegranskat)abstract
- The European transport simulator is a fusion machine simulator useful for making predictions of high-performance fusion plasmas, in particular for DT reactors. Recent developments introducing self-consistent simulations of combined RF + NBI heating schemes in which majority, minority and beam ions are simultaneously heated is documented. The predictive simulations are first validated by comparison with the experimental data on a DD JET baseline plasma. In order to prepare the next JET DTE2 experimental campaign, extrapolations of fusion performance on DT plasma from DD plasma are made with a particular focus on ion cyclotron resonance heating (ICRH) computation. Traditional ion cyclotron range of frequency heating models do not permit the study of Coulomb collisional interaction of various ion species simultaneously including neutral beam injection ions, and generally forces one to consider only minority populations. Accounting for multi-population interaction is made possible here by solving coupled sets of Fokker-Planck equations for all ion species adopting the non-linear collision operator for arbitrary distribution functions, accounting for effects, such as the self-collisions of majority (or large minority) populations. To answer the question whether H minority scheme or He-3 minority ICRH scheme is better for boosting the DT fusion performance, minority concentration scans are produced.
|
|
| 2. |
- Olasz, S., et al.
(författare)
-
Runaway electron modelling in the EU-IM framework
- 2021
-
Ingår i: 47th EPS Conference on Plasma Physics, EPS 2021. - : European Physical Society (EPS). ; 2021-June, s. 1156-1159
-
Konferensbidrag (refereegranskat)abstract
- The Runaway Electron Test Workflow was used to study the behaviour of the Dreicer generation of runaway electrons in dynamic scenarios to find a parameter which can be used to determine the need of kinetic modelling in more complex simulations. It was found that for processes which vary faster than the collision time at the critical velocity for runaway electron generation, kinetic modelling is advised to capture potential kinetic effects. A more complex tool, the ETS have been used to simulate a self-consistent thermal quench induced by massive material injection with promising initial results. Development of ETS capabilities continues with introduction of kinetic modelling and moving onto the new ETS6 versions.
|
|
| 3. |
- Olasz, S., et al.
(författare)
-
Validity of models for Dreicer generation of runaway electrons in dynamic scenarios
- 2021
-
Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 61:6
-
Tidskriftsartikel (refereegranskat)abstract
- Runaway electron modelling efforts are motivated by the risk these energetic particles pose to large fusion devices. The sophisticated kinetic models can capture most features of the runaway electron generation but have high computational costs, which can be avoided by using computationally cheaper reduced kinetic codes. This paper compares the reduced kinetic and kinetic models to determine when the former solvers, based on analytical calculations assuming quasi-stationarity, can be used. The Dreicer generation rate is calculated by two different solvers in parallel in a workflow developed in the European integrated modelling framework, and this is complemented by calculations of a third code that is not yet integrated into the framework. Runaway Fluid, a reduced kinetic code, NORSE, a kinetic code using non-linear collision operator, and DREAM, a linearized Fokker-Planck solver, are used to investigate the effect of a dynamic change in the electric field for different plasma scenarios spanning across the whole tokamak-relevant range. We find that on time scales shorter than or comparable to the electron-electron collision time at the critical velocity for runaway electron generation, kinetic effects not captured by reduced kinetic models play an important role. This characteristic time scale is easy to calculate and can reliably be used to determine whether there is a need for kinetic modelling or cheaper reduced kinetic codes are expected to deliver sufficiently accurate results. This criterion can be automated, and thus it can be of great benefit for the comprehensive self-consistent modelling frameworks that are attempting to simulate complex events such as tokamak start-up or disruptions.
|
|
