Speaker
Mr
David Schwörer
(Dublin City University, Ireland)
Description
Filaments are field aligned, non-linear density perturbations, which
have been observed in most plasmas.
In tokamaks they can
carry a significant amount of particles and heat from the last
closed flux surface to the far scrape-off layer (SOL).
This highly non diffusive transport mechanism
can cause a
significant heat load onto first wall materials. It is
important to understand
the motion of filaments,
particularly in regard to the
design of future fusion devices.
Recent experiments on several machines have shown that the plasma
density of the SOL can have a significant influence on the dynamics of
filaments.
We have carried out non-linear, 3D seeded filament simulations,
with the focus on
neutral-plasma interactions, using the BOUT++ library.
The model is an extension of the STORM code, which is a two
fluid model, including thermal electrons.
In order to study the influence of neutrals, 1D
background profiles
are computed.
By varying particle and heat influx, different profiles are generated.
The filaments of critical size showed an increasing radial velocity
with increasing
upstream temperature, as expected from scaling laws.
The filament further
showed a decreasing radial velocity with increasing plasma density.
In these conditions, the neutrals interaction resulted in a reduced
radial velocity.
It was further observed that the filaments radial velocity had a
strong dependency on the target temperature, resulting in an increasing
radial motion for an increasing target temperature.
As higher neutral densities could affect the strong sheath currents,
studying the neutrals filament interaction at higher
densities is of interest.
In the current study the density was further increased, as
the previous simulations showed an increasing influence of the
neutrals on the filaments with
increasing background plasma density and temperature on the filament.
The purely diffusive neutral model in STORM was extended to enable the
modelling of higher density conditions towards detachment.
This has been validated against other neutral simulation
codes.
This work has been carried out within the framework of
the EUROfusion Consortium and has received funding from the Euratom
research and training programme 2014-2018 under grant agreement No
633053.
| Country or International Organization | Germany |
|---|---|
| Paper Number | TH/P1-6 |
Primary author
Mr
David Schwörer
(Dublin City University, Ireland)
Co-authors
Benjamin D Dudson
(University of York, UK)
Dr
Fulvio Militello
(Culham Centre for Fusion Energy)
Dr
Huw Leggate
(Dublin City University, Ireland)
Miles M Turner
(Dublin City University, Ireland)
Dr
Nick Walkden
(Culham Centre for Fusion Energy)
