In this paper a search routine in MATLAB was developed in order to find and analyze oblique whistler waves in the data from the ESA and NASA spacecraft Solar Orbiter. Oblique whistler waves are a type of plasma wave which propagate at an angle with respect to the background magnetic field. They are efficient at scattering electrons in the solar wind but their role in interplanetary coronal mass ejections (ICMEs) is yet unknown. Magnetic field data from 1-31st of June 2022, as well as the 24th and 27-28th of January 2022 was examined. The search routine found six whistler waves in June and 12 for the dates in January. Among these, all found whistler waves were found in the sheath region of the ICMEs, and all had a plasma beta > 1. However due to instrumental artefacts the values of θk were found to be smaller than detected by the search routine, indicating less obliqueness than first expected. Some of the whistler waves seemed to have an obliqueness that changed with time and the bandwidth of the waves varied among the identified.

In this thesis, theoretical studies are conducted to see whether plasma will detach from the magnetic field lines of the VASIMR thruster, and if so, at which location detachment takes place. A magnetic field similar to the field of the VASIMR VF-24 engine [1] is used and ions of different speed and massare sent from various radial positions in the exhaust. Calculation with different values of the anomalous resistivity parameter ωτ is conducted and the sensitivity to this parameter is studied. The validity of the method is studied by comparing results to previous work by Carl Wesslén [2]. From the results it is concluded that using heavy ions sent at high speeds will achieve detachment and high thrust efficiency, even when assuming relatively high values of ωτ. Ejecting ions at a slower pace or using lighter ions will make the engine less efficient, requiring low ωτ which is difficult to achieve. For some combinations of mass and speed, detachment is not possible at all. Ions with heavy mass are recommended to use as propellant for this type of thruster.

Understanding of material migration and its impact on the formation of co-deposited mixed material layers on plasma-facing components is essential for the development of fusion reactors. This thesis focuses on this topic. It is based on experiments performed at JET and TEXTOR tokamaks. The major objectives were to determine: (i) fuel and impurity removal from plasma-facing components by ICWC in different gas mixtures, (ii) fuel and impurity transport connected to ICWC operation, (iii) plasma impact on diagnostic mirrors. All these issues are in line with the ITER needs: mitigation of co-deposition and fuel inventory, and the performance of first mirrors in long-term operation. The novelty in research is demonstrated by several elements. In wall conditioning studies, tracer techniques based on injection of rare isotopes (N-15, O-18) were used to determine conclusively the impact of respective gases. Also, a new approach to ICWC was developed by combining global gas balance studies based on mass spectrometry and the use of multiple surface probes exposed to discharges and then studied ex-situ with accelerator-based techniques. Impact of plasma on diagnostic mirrors was determined after exposure to the entire first experimental campaign in JET-ILW. / <p>QC 20141103</p>

The BIOMASS mission from the European Space Agency (ESA) is designed to measurebiomass and carbon content in Earth’s forests. To account for phase changes caused byionospheric variations, a map-drift autofocus algorithm is developed, which utilises a phasescreen of the ionosphere to eliminate phase errors in the signal. In this development, a filteris employed to integrate and remove noise from the second-order derivative of the ionosphericphase screen. This thesis aims to analyse methods to implement this filter andcompare their efficiency. Two filters are constructed using two methods, a Least Mean Square (LMS) filter and aWiener filter. Further emphasis is placed on the Wiener filter, and the most optimal way tocalculate it is explored in detail. The aim is to produce a filter that can integrate, lower theimpact of noise as much as possible and be computationally efficient. An implementationwas made in Python using simulated data of an ionosphere. The conclusion is that the Wiener filter can yield improved results if a precise estimation ofthe autocorrelation function of the ionospheric phase screen can be determined, and thatlinear regression models might be a method to do so. There is also consideration taken tothe noise of the data, it is compensated for by utilising multiple data sources. Additionally,to enhance computational efficiency, a comparison of different solving methods for the linearsystem of equations that is the filter where made, showing a LU-decomposition method tobe efficient.

This thesis serves as a preliminary design study for the combination of a flight-proven ion optics system (SWIM) with a conversion surface to create a small energetic neutral atom (ENA) sensor. It is planned to use this sensor as ENA sensor for the DFP-SCIENA instrument on Comet Interceptor. Due to the nature of the Comet Interceptor mission (ESA F-class mission with a maximum launch mass of 1000 kg) the development time for a new sensor that meets the size and weight restrictions is limited. The proposed combination of SWIM with a conversion surface is based on a proven ion optics design and should result in a compact sensor design. The main goal of this thesis was to simulate different conversion surface designs and evaluate their compatibility with the SWIM instrument. During this process the different designs were optimised based on the intermediate simulation results. The simulation process was performed by using SIMION to calculate particle trajectories.  In the end, two different conversion surface designs yielded promising results. With both designs detailed simulations and data analysis were conducted to determine the different properties of the two designs. One of these designs was chosen to be further investigated for use on the Comet Interceptor mission.

Charged particles constantly stream outward from the Sun to fill the solar system. These particles, consisting mainly of protons and electrons, form a plasma called the solar wind. The solar wind interacts with every celestial body in the solar system, giving rise to different phenomena, such as the auro- ras observed at high latitudes on Earth or disruption of the systems onboard artificial satellites.  The general structure of the solar wind has been established several decades ago, however we still do not fully understand how the solar wind properties, like temperature and velocity distribution, evolve as it propagates outward in the solar system. Observations of these properties cannot be explained from a conventional fluid description. In a system approximated as a fluid, particle collisions dictate its thermodynamic state. However, the solar wind is a weakly collisional plasma that deviates from thermodynamic equilibrium. Therefore, the radial evolution of the solar wind properties must be driven by different processes. In particular, wave-particle interactions are an important regulator of the solar wind properties, because of the strong connection between the electromagnetic fields and the charged particles.  In this thesis, we probe how the velocity distribution of solar wind par- ticles evolves as it travels from the Sun to the Earth. Specifically, we study the contribution of waves on the observed solar wind properties at different distances and how these waves can affect the interplanetary environment. We focus on two types of plasma waves frequently observed in the solar wind, Langmuir and ion-acoustic waves. We present their occurrence rates at differ- ent heliocentric distances and suggest wave generation mechanisms based on Solar Orbiter observations. We show that Langmuir waves in the unperturbed solar wind are more commonly observed in regions where the magnetic field magnitude is lower than the background value. Furthermore, we also find that the occurrence rate of ion-acoustic waves is increased in the ramp regions of interplanetary shocks observed at different heliocentric distances, compared to the ion-acoustic wave occurrence rate in the unperturbed solar wind.

A few years ago, the charge-transfer reaction CO2+  +  O ⟶ O+ + CO2 was investigated experimentally for the first time since the study by Fehsenfeld et al., (1970). This new investigation was conducted by Tenewitz et al., (2018). The rate coefficient k &lt; 6 × 10−13 cm3 s−1 , concluded by Tenewitz et al. (2018), differed substantially from the value of 9.6 × 10−11 cm3 s−1 reported by Fehsenfeld et al., (1970). Fox et al., (2021) showed that the old rate constants for the two channels of the CO2+  +  O interaction work much better than the new ones in reproducing chemical features of the Martian ionosphere. Here, we combine MAVEN/NGIMS and TIMED/SEE data to conduct model-observation comparisons of O+ concentrations in the dayside Martian ionosphere. We consider each orbit of the MAVEN Deep Dip 2 (DD2) campaign between 17-22 April 2015. In the model, we balance the production rate of O+ through the aforementioned charge transfer reaction and the photoionisation of O and CO2 , with the loss rate through the reaction O+ + CO2 ⟶ O2+ + CO. We find a better level of agreement between the modelled and the observed O+ concentrations— (i) towards closest approach altitudes (∼ 130 km), and (ii) when using the old rate constant instead of the new one for the charge transfer reaction CO2+ +  O ⟶ O+ + CO2 .

The region of space dominated by the Sun's magnetic field is called the heliosphere. It envelops the entire solar system including Earth. Therefore, a strong coupling exists between the Sun and our planet. The Sun continuously ejects particles, the solar wind, and when these high energy particles hit Earth, the magnetosphere (the region around the Earth governed by the geomagnetic field) is affected. When the solar wind is enhanced this disturbs the magnetosphere and perturbations can be seen also in ground-based observations. The upper atmosphere is subjected to solar radiation that ionise the neutral atoms and molecules, this region is referred to as the ionosphere. In the ionosphere, some of the heavier ion populations, such as O+, are heated and accelerated through several processes and flow upward. In the polar regions these mechanisms are particularly efficient and when the ions have enough energy to escape the Earth's gravity, they move outward along open magnetic field lines and may be lost into interplanetary space. Ion outflow in general has already been well studied, however, ion outflow under extreme magnetospheric conditions has not been investigated in detail. Disturbed magnetospheric conditions correlate with solar active periods, such as coronal holes or the development of solar active regions. From these regions, strong ejections called coronal mass ejections (CMEs) emerge. When these extreme events interact with Earth, they produce a compression of the magnetosphere as well as reconnection between the terrestrial magnetic field lines and the interplanetary magnetic field (IMF) lines, which most of the time leads to geomagnetic storms. The amounts of incoming solar particles and energy increase during geomagnetic storms and we also observe an increase in the O+ outflow. Our observations are made with the Cluster mission, a constellation of 4 satellites flying around Earth in the key magnetospheric regions where ion outflow is usually observed. In this thesis, we estimate O+ outflow under disturbed magnetospheric conditions and for several extreme geomagnetic storms. We find that O+ outflow lost into the solar wind increases exponentially with enhanced geomagnetic activity (Kp index) and increases about 2 orders of magnitude during extreme geomagnetic storms. / Den del av rymden som domineras av solens magnetfält kallas heliosfären. Helios-fären omfattar hela solsystemet inklusive jorden, vilket gör att det finns en starkkoppling mellan solen och jorden. Solen sänder oavbrutet ut laddade partiklar in denså kallade solvinden och när dessa energika partiklar träffar jorden påverkas mag-netosfären (det område kring jorden där det geomagnetiska fältet dominerar). Närsolvinden är starkare än vanligt uppstår störningar. I magnetosfären som ger effektersom kan uppmätas med markbaserade instrument. Den övre atmosfären utsätts för strålning från solen som joniserar atomer ochmolekyler, och formar det område som kallas jonosfären. Några av de tyngre jonpop-ulationerna i jonosfären, som till exempel syrejoner, kan hettas upp och accelererasgenom flera olika möjliga processer. Detta gör att de flödar uppåt i atmosfären. Ipolarområdena är dessa mekanismer särskilt effektiva och om tillräckligt med energitillförs jonerna kan gravitationen övervinnas, vilket gör att jonerna flödar upp längsöppna magnetfältlinjer och kan gå förlorade ut i den interplanetära rymden. Generelltsett har jonutflöde redan studerats väl, men jonutflöde under extrema magnetosfäriskaförhållanden har inte undersökts i detalj. Störda magnetosfäriska förhållanden korrelerar med då solen är aktiv, som tillexempel koronahål eller under utvecklingen av aktiva solområden. Från dessa områ-den härstammar koronamassautkastningar. När dessa extrema händelser når jordenkomprimeras magnetosfären och det geomagnetiska och interplanetära magnetiskafältet omkopplas, vilket ofta leder till geomagnetiska stormar. Under dessa införsstora mängder av partiklar i solvinden och energi till magnetosfären, och ett högresyrejonsutflöde är också observerat. Data från Clustersatelliterna har använts; dessa utgörs av fyra satelliter i for-mation i omloppsbana kring jorden. Plasmaområdena där de befinner sig är därjonutflödet vanligtvis observeras. Denna avhandling behandlar syrejonsutflöde understörda magnetosfäriska förhållanden och flera extrema geomagnetiska stormar. Detvisas att syrejonsutflödet som förloras till solvinden ökar exponentiellt med geomag-netiskt aktivitet (Kp-index) och ökar med upp till 2 storleksordningar under extremageomagnetiska stormar.

Following previous studies, a theoretical model for the induced magnetic field by Europa, one of Jupiter's icy moons, is presented. The aim of the model is to find evidence for the existence of a sub-surface ocean on the moon. Moreover, the accuracy of the theoretical model is evaluated using data from the Galileo space probe and a discussion of improvements, with the upcoming mission JUICE in mind, is given. The magnetic field from Jupiter is modeled using a dipole field and the moon is assumed to have the properties of a perfect homogeneous conductive layer (i.e a superconductor with no resistance). Europa is assumed to possess an electrically conductive subsurface ocean with conductivity $\sigma$. As the moon orbits Jupiter, the moon will experience a time-varying magnetic field since the magnetic dipole axis is tilted with an angle with respect to the rotation axis of the planet. The fact that the moon experiences a time-varying magnetic field will cause an inductive response inside the moon if a conductive material is present.  However, since this set-up reflects the ideal case, a discussion of constraints and improvements is submitted as a compliment. This thesis shows that the ocean model for Europa is supported, but further evidence is needed to fully understand the structure of the moon. The model shows a clear induction in almost all Galileo-flybys investigated, especially flyby E4 and E14. Thereby, it can be argued that the model gives a representative picture of the true induced magnetic field, with room for improvement.  In conclusion, further data is needed to fully reveal the structure of the moon, a fact that lays the foundation for the coming JUICE mission. JUICE will study both the magnetic and the electric field of Jupiter, and analyze the inner structures of the Galilean moons with higher precision than ever

A python code was developed to compute the alpha knock-on (AKN) neutron spectrum using two already available computational tools. The code was used to calculate the AKN for a given discharge from the DTE2 JET campaign. Results showed that the beam-target contribution dominated the neutron spectra and obscured the AKN tail. A spatial profile of the AKN intensity was created which showed that the majority of the AKN reactions happen in the center of the plasma, but further analysis is needed to get a better picture of whether the AKN component will be measurable or not.