4DSpace#
In the strategic research initiative 4DSpace we study instabilities and turbulence in the polar ionosphere with an integrated, multi-scale 4D (3D in space and time) experimental, theoretical, and modelling approach.
Two of my previous PhD students Diako Darian and Sigvald Marholm have both been working under the 4DSpace umbrella, that altogether count approximately 40 people. We are focusing on developing unstructured Particle In Cell (PIC) codes with finite element and Lagrangian particle methods, within the FEniCS framework. See [Marholm et al., 2020] and the Particles in UNstructured Cells code PUNC.
In the paper by [Darian et al., 2017] we use PIC simulations of a sounding rocket in ionospheric plasma to investigate effects of magnetic field on the wake formation and rocket potential. In the paper by [Miloch et al., 2018] we study dynamic ion shadows behind finite-sized objects in collisionless magnetized plasma flows.
[Darian and Mortensen, 2015] have implemented a spectral MagnetoHydroDynamics solver with the Boussinesq approximation for variable densities within the spectralDNS framework, and use it to study Kelvin-Helmholtz instabilities in stratified and unstratified shear layers.
[Miloch et al., 2017] study the wake potential of a dust particle in magnetised plasmas. In [Darian et al., 2019] we use simulations to study spherical and cylindrical Langmuir probes in non-Maxwellian plasmas, whereas [Marholm et al., 2019] investigates the response of miniaturized fixed-bias multi-needle Langmuir probes on a CubeSat satellite. In [Marholm et al., 2020] we describe a novel numerical method that incorporates electrically conducting objects into particle-in-cell simulations of electrostatic plasma. The method allows multiple objects connected by voltage and current sources in an arbitrary circuit topology.
References#
D Darian, S Marholm, M Mortensen, and W J Miloch. Theory and simulations of spherical and cylindrical langmuir probes in non-maxwellian plasmas. Plasma Physics and Controlled Fusion, 61(8):085025, jun 2019. doi:10.1088/1361-6587/ab27ff.
D. Darian, S. Marholm, J. J. P. Paulsson, Y. Miyake, H. Usui, M. Mortensen, and W. J. Miloch. Numerical simulations of a sounding rocket in ionospheric plasma: effects of magnetic field on the wake formation and rocket potential. Journal of Geophysical Research: Space Physics, 122(9):9603–9621, 2017. doi:10.1002/2017JA024284.
Diako Darian and Mikael Mortensen. A pseudo-spectral study of kelvin-helmholtz instability. In Proceedings of the eighth national conference on computational mechanics, MekIT'15. 2015. URL: https://www.researchgate.net/profile/Mikael-Mortensen-2/publication/294088678_A_PSEUDO-SPECTRAL_STUDY_OF_KELVIN-HELMHOLTZ_INSTABILITY/links/56bdf42e08ae44da37f883d8/A-PSEUDO-SPECTRAL-STUDY-OF-KELVIN-HELMHOLTZ-INSTABILITY.pdf.
W J Miloch, D Darian, and M Mortensen. Wake potential of a dust particle in magnetised plasmas. Physica Scripta, 92(11):114006, oct 2017. doi:10.1088/1402-4896/aa90a5.
W J Miloch, H Jung, D Darian, F Greiner, M Mortensen, and A Piel. Dynamic ion shadows behind finite-sized objects in collisionless magnetized plasma flows. New journal of Physics, 20(7):073027, jul 2018. doi:10.1088/1367-2630/aad066.
S. Marholm, D. Darian, M. Mortensen, R. Marchand, and W. J. Miloch. A novel method for circuits of perfect electric conductors in unstructured particle-in-cell plasma–object interaction simulations. IEEE Transactions on Plasma Science, 48(8):2856–2872, 2020. doi:10.1109/TPS.2020.3010561.
S. Marholm, R. Marchand, D. Darian, W. J. Miloch, and M. Mortensen. Impact of miniaturized fixed-bias multineedle langmuir probes on cubesats. IEEE Transactions on Plasma Science, pages 1–9, 2019. doi:10.1109/TPS.2019.2915810.