{"id":37,"date":"2017-01-18T21:47:55","date_gmt":"2017-01-18T21:47:55","guid":{"rendered":"http:\/\/10.0.1.5\/?page_id=37"},"modified":"2026-05-31T19:16:48","modified_gmt":"2026-05-31T19:16:48","slug":"research","status":"publish","type":"page","link":"https:\/\/verscharen.com\/?page_id=37","title":{"rendered":"Research"},"content":{"rendered":"\n

What is Plasma Physics?<\/h2>\n\n\n\n

\"\"In my research, I study the fundamental physics of plasmas. A plasma is a gas in which the ions and electrons are separated from each other and do not form neutral atoms like in a regular gas. The moving charged plasma particles modify and react to electric and magnetic fields. These interactions lead to a behaviour that is very different from the behaviour of neutral gases like the air. In these complex systems, collective processes emerge, and methods from the field of statistical physics are required for their understanding. We can measure plasmas in our cosmic neighbourhood directly and in situ with the help of spacecraft in our solar system. This is particularly the case for space plasmas such as the solar wind, the solar corona, planetary plasmas, and the Earth’s plasma environment. <\/p>\n\n

By working in close dialogue with measurements in space plasmas, we learn about fundamental plasma processes that are important for astrophysical systems across our Universe. These systems include accretion discs around black holes, the interstellar medium, or the plasma between galaxies. Solar-terrestrial interactions between space plasma systems and the Earth cause space weather, which can have a serious impact on our modern, technological society.<\/p>\n\n\n\n

\"\"Under certain conditions, a plasma can be described like a fluid (for example with the equations of magnetohydrodynamics), but often a description based on kinetic physics<\/i>, a sub-field of statistical mechanics, is necessary. I work on the kinetic physics of collisionless plasmas. I am especially interested in waves and instabilities, wave-particle interactions, weak collisions, turbulence, plasma heating, shock waves, and multi-scale couplings.<\/p>\n\n\n\n

Interdisciplinary Plasma Physics<\/h2>\n\n\n\n

Plasmas occur not just in the space environment of our solar system. In fact, almost all the visible matter in the Universe is in the plasma state. Therefore, the understanding of plasma as the fourth state of matter<\/i> has vital links to the wider field of astrophysics. Moreover, plasma physics is investigated in plasma laboratories here on Earth in which plasmas are created artificially. Plasmas have many technological applications, reaching from surface treatments over medical applications to the harnessing of nuclear fusion for the generation of energy. Given this ubiquity of plasmas, the field of plasma physics is inherently interdisciplinary. I am very interested in these interdisciplinary interactions across the different branches in plasma physics. Therefore, I have organised and co-organised many interdisciplinary activities across the boundaries of the research communities with interest in plasma physics. <\/p>\n\n

\"\"In 2024, I organised the ISSI Workshop: Electron Kinetic Physics: The Next Frontier in Space and Astrophysical Plasmas<\/a>. This workshop provided a unique opportunity for plasma physicists from different communities (astrophysical plasmas, heliospheric plasmas, laser plasmas) to discuss and compare the similarities and differences in the properties of these processes. While the workshop revealed a striking similarity of the processes over a wide range of spatial scales, it also emphasised the strong need for a common framework for inferring kinetic plasma properties from remote sensing observations as the key to their understanding. <\/p>\n\n

\"\"In 2025, I organised the ISSI Forum: Exploring the Synergies between Space and Laboratory Plasma Physics<\/a>. This interdisciplinary ISSI Forum brought together world-leading experts in space plasma physics and laboratory plasma physics to explore and discuss the synergies between both research strands and scientific communities. The scientific scope of our Forum lay on the physics of fundamental processes that can play a significant role in defining the behaviour of both space and laboratory plasmas. These processes include, amongst others, magnetic reconnection, turbulence and waves, nonequilibrium effects and instabilities, shocks, Coulomb collisions, dynamo effects, and heat conduction.<\/p>\n\n

\"\"In 2026, I co-organised the NORDITA Scientific Programme: Synergies between Astrophysical, Space, Laboratory, and Fusion Plasma Physics<\/a>. This Scientific Programme brought together world-leading experts in plasma physics to explore and discuss the synergies among the different research strands and scientific communities. Their common interest in the discovery and understanding of fundamental processes in complex plasma systems offers great opportunities for cross-fertilisation and bi-directional exchange of ideas, as well as the exploration of common themes and concepts. The central goal of this Scientific Programme was to break the community barriers and to open a pathway towards more detailed and larger-scale, synergistic follow-on research projects and collaborations.<\/p>\n\n\n\n

Research Highlights<\/h2>\n\n\n\n

\"\"

Image Credit: NASA’s WIND spacecraft from nasa.gov<\/p><\/div> Our research on the comparison between kinetic and fluid models of compressive fluctuations in the solar wind has been featured in a UNH press release. We compared predictions for the three lowest velocity moments from gyrokinetic theory with magnetohydrodynamics (MHD) and solar-wind observations from the WIND spacecraft. Surprisingly, the MHD predictions agree better with the observations than the kinetic predictions. This finding has a strong impact on our modelling efforts of space plasma, since it suggests that MHD models actually work better than expected. For example, our research supports the use of MHD models for the prediction of space weather. However, more research is needed to understand the physics and the broader implications of our results. Here is the link to the press release:
https:\/\/www.unh.edu\/unhtoday\/news\/release\/2017\/05\/15\/unh-researcher-identifies-key-differences-solar-wind-models<\/a><\/p>\n\n\n\n

\"\"Our research on the scattering of the electron strahl has been featured in a UCL press release. The electron strahl is a beam of faster electrons that travel through the solar wind along the magnetic field and away from the Sun. Although this strahl has often been observed, we still don’t understand its generation in the solar corona or its evolution as it travels through the space between the planets. Our theory suggests that the strahl electrons are scattered by an instability of a certain type of plasma wave: the oblique fast-magnetosonic\/whistler wave. The strahl electrons can create this instability themselves as they move along the magnetic field. Our initial comparison with spacecraft data supports our theory. However, we must test this with more detailed measurements in the future. Solar Orbiter will deliver excellent data for this purpose. Here is the link to the press release:
https:\/\/www.ucl.ac.uk\/mathematical-physical-sciences\/news\/2019\/dec\/ucl-study-electrons-solar-wind-appears-astrophysical-journal<\/a><\/p>\n\n\n\n

\"\"With two of my colleagues, I have written the review article “The multi-scale nature of the solar wind”<\/a>. This open-access article describes the plasma physics in the solar wind that couples the large scales with the small scales. It includes a brief, general introduction to the plasma physics of the solar wind, a description of measurement techniques used on spacecraft, and discussions of collisions, waves, turbulence, and kinetic instabilities in the solar wind. We have written this review article for early-stage PhD students or early-career post-docs entering the field of solar-wind research. As a truly Living Review, we will update the article continuously.<\/p>\n\n\n\n

\"\"This movie shows an isosurface of the proton velocity distribution function in the solar wind. It was observed by the Helios spacecraft in the 1970s. The distribution function fully describes the kinetic state of the plasma particles. The little bump on the upper side of this isosurface represents the “proton beam”, which is a bunch of faster protons that stream through the core protons. Solar Orbiter and Parker Solar Probe measure distribution functions with great resolution.<\/p>\n\n\n\n

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What is going on here?<\/h4>\n\"\"\n","protected":false},"excerpt":{"rendered":"

What is Plasma Physics? In my research, I study the fundamental physics of plasmas. A plasma is a gas in which the ions and electrons are separated from each other and do not form neutral atoms like in a regular gas. The moving charged plasma particles modify and react to electric and magnetic fields. These […]<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-37","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/verscharen.com\/index.php?rest_route=\/wp\/v2\/pages\/37","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/verscharen.com\/index.php?rest_route=\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/verscharen.com\/index.php?rest_route=\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/verscharen.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/verscharen.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=37"}],"version-history":[{"count":82,"href":"https:\/\/verscharen.com\/index.php?rest_route=\/wp\/v2\/pages\/37\/revisions"}],"predecessor-version":[{"id":1486,"href":"https:\/\/verscharen.com\/index.php?rest_route=\/wp\/v2\/pages\/37\/revisions\/1486"}],"wp:attachment":[{"href":"https:\/\/verscharen.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=37"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}