| 1. |
- Labit, B., et al.
(författare)
-
Dependence on plasma shape and plasma fueling for small edge-localized mode regimes in TCV and ASDEX Upgrade
- 2019
-
Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 59:8
-
Tidskriftsartikel (refereegranskat)abstract
- © 2019 Institute of Physics Publishing. All rights reserved. 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.
|
|
| 2. |
|
|
| 3. |
- Bohm, P., et al.
(författare)
-
Edge Thomson scattering diagnostic on COMPASS tokamak : Installation, calibration, operation, improvements
- 2014
-
Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 85:11, s. 11E431-
-
Tidskriftsartikel (refereegranskat)abstract
- The core Thomson scattering diagnostic (TS) on the COMPASS tokamak was put in operation and reported earlier. Implementation of edge TS, with spatial resolution along the laser beam up to similar to 1/100 of the tokamak minor radius, is presented now. The procedure for spatial calibration and alignment of both core and edge systems is described. Several further upgrades of the TS system, like a triggering unit and piezo motor driven vacuum window shutter, are introduced as well. The edge TS system, together with the core TS, is now in routine operation and provides electron temperature and density profiles.
|
|
| 4. |
- Komm, M., et al.
(författare)
-
Simulations of thermionic suppression during tungsten transient melting experiments
- 2017
-
Ingår i: Physica Scripta. - : Institute of Physics (IOP). - 0031-8949 .- 1402-4896. ; T170
-
Tidskriftsartikel (refereegranskat)abstract
- Plasma-facing components receive enormous heat fluxes under steady state and especially during transient conditions that can even lead to tungsten (W) melting. Under these conditions, the unimpeded thermionic current density emitted from the W surfaces can exceed the incident plasma current densities by several orders of magnitude triggering a replacement current which drives melt layer motion via the J x B force. However, in tokamaks, the thermionic current is suppressed by space-charge effects and prompt re-deposition due to gyro-rotation. We present comprehensive results of particle-in-cell modelling using the 2D3V code SPICE2 for the thermionic emissive sheath of tungsten. Simulations have been performed for various surface temperatures and selected inclinations of the magnetic field corresponding to the leading edge and sloped exposures. The surface temperature dependence of the escaping thermionic current and its limiting value are determined for various plasma parameters; for the leading edge geometry, the results agree remarkably well with the Takamura analytical model. For the sloped geometry, the limiting value is observed to be proportional to the thermal electron current and a simple analytical expression is proposed that accurately reproduces the numerical results.
|
|
| 5. |
- Panek, R., et al.
(författare)
-
Anomalous ion diffusion and radial-electric-field generation in a turbulent edge plasma potential weakly correlated in time and space
- 2005
-
Ingår i: Physica Scripta. - 0031-8949 .- 1402-4896. ; 72:4, s. 327-332
-
Tidskriftsartikel (refereegranskat)abstract
- Using a simple model of tokamak-edge-plasma turbulence in the form of a spatially periodic and time-independent electrostatic potential, we have found recently a new type of anomalous impurity diffusion in this regime [1], [2]. In the present contribution, we estimate this diffusion in the test-particle approach for a real turbulent potential obtained in an experiment. A significant difference in the impurity dynannics between the Hamiltonian and drift approaches is observed. As an interesting consequence of these dynamics, the possibility of radial-electric-field generation in the turbulence regimes appears. This effect can be of importance in scenarios related to transport barriers.
|
|
| 6. |
|
|
| 7. |
- Komm, M., et al.
(författare)
-
Contribution to the multi-machine pedestal scaling from the COMPASS tokamak
- 2017
-
Ingår i: Nuclear Fusion. - : Institute of Physics (IOP). - 0029-5515 .- 1741-4326. ; 57:5
-
Tidskriftsartikel (refereegranskat)abstract
- First systematic measurements of pedestal structure during Ohmic and NBI-assisted Type I ELMy H-modes were performed on the COMPASS tokamak in two dedicated experimental campaigns during 2015 and 2016. By adjusting the NBI heating and a toroidal magnetic field, the electron pedestal temperature was increased from 200 eV up to 300 eV, which allowed reaching pedestal collisionality nu(ped)* < 1 at q(95) similar to 3. COMPASS has approached conditions for the Identity experiment done at JET & DIII-D, complementing the range of scanned rho(ped)*. The pedestal pressure was successfully reproduced by the EPED model. The dependence of pedestal pressure width on nu(ped)* and beta(pol)(ped) is discussed.
|
|
| 8. |
- Krlin, L., et al.
(författare)
-
Anomalous impurity diffusion in models of tokamak edge plasma turbulence
- 2004
-
Ingår i: Czechoslovak Journal of Physics. - 0011-4626 .- 1572-9486. ; 54:1-3, s. 157-163
-
Tidskriftsartikel (refereegranskat)abstract
- Using a simple spatially periodical and stationary potential as a model of electrostatic tokamak edge plasma turbulence, we have found recently [1, 2] an anomalous impurity diffusion in this regime. In this contribution, we estimate this diffusion for a more general and realistic form of the potential, which is close to the Hasegawa-Wakatani (HW) potential. As an interesting consequence of the discussed dynamics, we present, possibility of radial electric field generation in the edge turbulence regime. This effect. might play a role in tokamak scenarios with transport barriers.
|
|
| 9. |
- McDevitt, Allan D., et al.
(författare)
-
Next-generation phylogeography resolves post-glacial colonization patterns in a widespread carnivore, the red fox (Vulpes vulpes), in Europe
- 2022
-
Ingår i: Molecular Ecology. - : Wiley. - 0962-1083 .- 1365-294X. ; 31:3, s. 993-1006
-
Tidskriftsartikel (refereegranskat)abstract
- Carnivores tend to exhibit a lack of (or less pronounced) genetic structure at continental scales in both a geographic and temporal sense and this can confound the identification of post-glacial colonization patterns in this group. In this study we used genome-wide data (using genotyping by sequencing [GBS]) to reconstruct the phylogeographic history of a widespread carnivore, the red fox (Vulpes vulpes), by investigating broad-scale patterns of genomic variation, differentiation and admixture amongst contemporary populations in Europe. Using 15,003 single nucleotide polymorphisms (SNPs) from 524 individuals allowed us to identify the importance of refugial regions for the red fox in terms of endemism (e.g., Iberia). In addition, we tested multiple post-glacial recolonization scenarios of previously glaciated regions during the Last Glacial Maximum using an Approximate Bayesian Computation (ABC) approach that were unresolved from previous studies. This allowed us to identify the role of admixture from multiple source population post-Younger Dryas in the case of Scandinavia and ancient land-bridges in the colonization of the British Isles. A natural colonization of Ireland was deemed more likely than an ancient human-mediated introduction as has previously been proposed and potentially points to a larger mammalian community on the island in the early post-glacial period. Using genome-wide data has allowed us to tease apart broad-scale patterns of structure and diversity in a widespread carnivore in Europe that was not evident from using more limited marker sets and provides a foundation for next-generation phylogeographic studies in other non-model species.
|
|
| 10. |
- Panek, P, et al.
(författare)
-
Investigations to develop a fully adjustable intelligent toilet for supporting old people and persons with disabilities - The Friendly Rest Room (FRR) project
- 2004
-
Ingår i: Computers Helping People with Special Needs (Lecture Notes in Computer Science). - Berlin, Heidelberg : Springer Berlin Heidelberg. - 0302-9743 .- 1611-3349. - 9783540223344 ; 3118, s. 392-399
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- The FRR (Friendly Rest Room) project creates and evaluates prototypes of a more user friendly intelligent toilet for old persons and for persons with disabilities. Additionally, applicable knowledge regarding needs and wishes of old and/or disabled persons and their care persons are documented. In this paper the user driven research approach, ethical aspects and the iterative user centred design process are outlined. First results from user tests of lighting, human computer interface and preferred seating heights are described.
|
|
