Space Plasma Research at UCL/MSSL

We are active in a number of areas of Space Plasmas Research, driven by our current and future participation in international space science missions for which we have, or will provide instrument hardware.  These include interests in the solar wind, and the terrestrial and planetary magnetospheres.  

Illustration of the proposed model for the polar hole origin of the fast solar wind by Tu & Marsch (2005)

The solar wind is a stream of plasma that flows radially outwards from the Sun, carrying with it the solar magnetic field. It is a supersonic plasma that is shocked by its encounters with bodies throughout the solar system. The source of the solar wind and its evolution through the solar system are areas of active research within the Space Plasma Physics group at MSSL.

We are the principal investigator institute for the Solar Wind Analyser (SWA) suite of sensors which are selected for inclusion on ESA’s Solar Orbiter Mission.  This mission, targeted for launch in January 2017, is a candidate to be the first component of ESA’s Cosmic Vision 2015-2025 Programme.  As well as leading the international SWA consortium, preparations for this mission at UCL/MSSL include the scientific analysis of current space-based observations of the solar wind, which acts to inform the design and prototyping work for the SWA Electron Analyser System (SWA/EAS), which will be built at UCL/MSSL.

We work in close collaboration with the UCL/MSSL Solar Physics group in order to better our understanding between phenomena on the Sun and their propagation into the solar system.

Artist's impression of plasma regions of the magnetosphere

We are engaged in the scientific study of the structures and dynamics of a number of regions found within and around the Earths magnetosphere, including the magnetospheric cusps, the magnetopause and the magnetotail. We are particularly interested in magnetic reconnection, and its manifestations at the magnetopause (for example through studies of Flux Transfer Events) and in the magnetotail (in particular the physics of magnetospheric substorm and related phenomena). In addition, recent work concentrates also on the auroral regions, and the physical processes which accelerate particles precipitating from the magnetosphere to the energies needed for auroral activation.

The principal tool we use for magnetospheric research is data from the ESA 4-spacecraft Cluster mission and China/ESA 2-spacecraft Double Star mission. UCL/MSSL is the Principal Investigator Institute for the Electron Spectrometer instrument (PEACE) flown on all 6 of these spacecraft.  We also use data from the Polar, Interball, Geotail, ACE, Wind and THEMIS satellites.  

Artist impression of Jupiter and its moons. Image courtesy John Spencer

Often in close collaboration with members of the UCL/MSSL Planetary Group, members of the Space Plasmas Group regularly participate in studies of the plasma environments (magnetospheres, ionospheres, plasma wakes, etc.) of other solar system bodies.

Our expertise in studying the plasma environment around the Earth and the abundance of data available allow us to study the similarities and differences between the different planetary systems throughout the solar system. Through these comparisons, we can further our understanding of the fundamental physics of plasmas. 

MSSL Space Plasma Science Nuggets

Plot of magnetotail properties against solar wind driving: (a) Magnetic pressure in the lobes; (b) total pressure in the plasma sheet (magnetic pressure + H+ + O+); (c) plasma sheet ion temperature; and (d) plasma sheet ion density. The overlaid boxes show the median (blue line), upper and lower quartiles (large box) and upper and lower deciles (small box) of the ordinate data split into deciles of the solar wind driving from the entire data set. The grey lines show the fits to our semiempirical model. The solid lines show fits of these models to the whole data set, and the dashed lines show fits to the shown median values. From Forsyth et al., GRL, 2014

Increases in plasma sheet temperature with solar wind driving during substorm growth phases

Through its interaction with the solar wind, Earth's magnetosphere can store 1015 J of magnetic energy in its magnetotail. This energy is explosively released during magnetospheric substorms; events during which the stored magnetic energy is directed into the ionosphere to cause the aurora, heats in the plasma in the magnetotail and is ejected back into the solar wind behind the magnetosphere. More...

Figure 1.  Auroral observations during a  substorm. (a) and (b) North-south slice through the aurora from two auroral cameras close-by in white-light, and (c) and (d) in red-line and blue-line auroral emission, respectively.   (e)-(h) shows east-west slices through the auroral cameras, showing the formation and evolution of wave-like auroral beads at the start of this substorm.

Inner magnetospheric onset preceding reconnection and tail dynamics during substorms: Can substorms initiate in two different regions?

The explosive release of energy within a substorm marks the beginning of one of the most dynamic and vibrant auroral displays seen in the night-time skies.  Stored magnetic energy is quickly converted to plasma kinetic energy, resulting in dramatic changes both in the large-scale magnetic topology of the Earth’s night-side magnetic field, and in energetic particles being accelerated towards Earth. More...

Ionospheric waves observed by EISCAT radar in Tromso, Norway

Waves in the ionosphere detected by ground GPS receiver network

Ground networks of GPS receivers can be used to characterise ionospheric perturbations. As the dual frequency navigational GPS signal propagates through the ionosphere, due to dispersive properties of the ionised media it carries information about the total ionospheric electron content (TEC). With careful analysis, ionospheric perturbations due to various natural drivers can be detected. Ground networks of GPS receivers in Japan have been used to detect small ionospheric effects from propagating extra long ocean waves, those causing catastrophic tsunamis as they reach the shore. In Scandinavia and Canada, the effects from auroral activity and from magnetospheric plasma waves have been observed in GPS TEC measurements. Such effects can be of crucial importance for the precise GPS positioning but can be also utilised to monitor the Earth’s magnetosphere and in particular the radiation belts. More...

Schematic showing the layers of an FTE. From Varsani et al. (2014)

High-time-resolution observations of an FTE using Cluster

We have presented the Cluster observations of a crater FTE on 12 February 2007, when the quartet was located in the low-latitude boundary layer, and widely separated on the magnetopause plane. The passage of the structure was sequentially observed by Cluster 2, 3, 4 and 1 respectively, analysed in detail. But what are flux transfer events, and why are they important within the magnetosphere? More...

Azimuthal electric field PSD values derived from ground-based magnetometer measurements of the D-component magnetic field PSD at L = 7.94, 6.51, 5.40, 4.26, 4.21, 2.98, and 2.55. The dashed lines represent constant fits to these PSD values. From Ozeke et al. (2014)

New and improved analytic expressions for ULF wave radiation belt radial diffusion coefficients

Ozeke et al. [2014] presented analytic expressions for ULF wave-derived radiation belt radial diffusion coefficients, as a function of L and Kp, which can easily be incorporated into global radiation belt transport models. The diffusion coefficients are derived from statistical representations of ULF wave power, electric field power mapped from ground magnetometer data, and compressional magnetic field power from in situ measurements.

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