Your search
Results 8 resources
-
Numerical instabilities of standard Particle-In-Cell (PIC) codes were observed and explained very early in their development. In the zero-time step limit, these instabilities arise from the interaction between the spatial grid and the (artificial) particle shape functions. δf PIC codes, which have recently been especially popular in gyrokinetic simulations, suffer from similar instabilities....
-
The strong, sharp flow structures that are seen frequently in tokamak cores, and large amplitude spontaneous global toroidal rotation are both surprising in light of current theories where toroidal flow evolution is dominantly diffusive. Mechanisms for spontaneously generating strong poloidal shear flows have been extensively investigated, but these processes were thought not to apply to...
-
The performance of spherical tokamak reactors depends on plasma β, and an upper limit is set by long-wavelength kinetic ballooning modes (KBMs). We examine how these modes become unstable in spherical-tokamak reactor relevant plasmas, which may contain significant fast-ion pressure. In a series of numerically generated equilibria of increasing β, the KBM becomes unstable at sufficiently high...
-
We discuss theoretical and numerical aspects of gyrokinetics as a Lagrangian field theory when the field perturbation is introduced into the symplectic part. A consequence is that the field equations and particle equations of motion in general depend on the time derivatives of the field. The most well-known example is when the parallel vector potential is introduced as a perturbation, where a...
-
The formation of density corrugation due to zonal flow, so-called zonal staircase, is investigated theoretically, based on the wave-kinetic framework. The wave-kinetic simulation is performed, considering the profile corrugation and the turbulence trapping mechanism, where the profile corrugation changes the growth rate and the dispersion relation of turbulence. The zonal density is generated...
-
Spatially non-local aspects of turbulent transport in tokamak plasmas are examined with global gyrokinetic simulations using the ORB5 code. Inspired by very accurate measurements in the TCV tokamak in L-mode, we initialise plasma profiles with constant logarithmic gradients in the core and constant linear gradients in the ‘pedestal’ (). The main finding is that transport in the core is...
-
The work reported in this paper addresses two aspects. In the first part, numerical simulations are conducted to examine the impact of magnetic equilibrium shaping (elongation and triangularity), on both conventional Ion Temperature Gradient (ITG) modes and Short Wavelength ITG modes. This analysis is performed considering the experimental profiles and parameters of the ADITYA-U tokamak,...
-
This paper presents the current state of the global gyrokinetic code Orb5 as an update of the previous reference (Jolliet et al., 2007). The Orb5 code solves the electromagnetic Vlasov–Maxwell system of equations using a PIC scheme and also includes collisions and strong flows. The code assumes multiple gyrokinetic ion species at all wavelengths for the polarization density and drift-kinetic...
Explore
Topic
Outputs
- Publications (8)
Tools used by TDoTP
- Code (1)
Resource type
- Journal Article (8)
Publication year
-
Between 2000 and 2025
(8)
-
Between 2010 and 2019
(2)
- 2019 (2)
- Between 2020 and 2025 (6)
-
Between 2010 and 2019
(2)
Resource language
- English (5)