The Effects of Spacecraft Potential on Ionospheric Ion Measurements

Abstract. The two PEACE (Plasma Electron And Current Experiment) sensors on board each Cluster spacecraft sample the electron velocity distribution across the full 4<pi> solid angle and the energy range 0.7 eV to 26 keV with a time resolution of 4 s. We present high energy and angular resolution 3D observations of electrons of spacecraft origin in the various environments encountered by the Cluster constellation, including a lunar eclipse interval where the spacecraft potential was reduced but remained positive, and periods of ASPOC (Active Spacecraft POtential Control) operation which reduced the spacecraft potential. We demonstrate how the spacecraft potential may be found from a gradient change in the PEACE low energy spectrum, and show how the observed spacecraft electrons are confined by the spacecraft potential. We identify an intense component of the spacecraft electrons with energies equivalent to the spacecraft potential, the arrival direction of which is seen to change when ASPOC is switched on. Another spacecraft electron component, observed in the sunward direction, is reduced in the eclipse but unaffected by ASPOC, and we believe this component is produced in the analyser by solar UV. We find that PEACE anodes with a look direction along the spacecraft surfaces are more susceptible to spacecraft electron contamination than those which look perpendicular to the surface, which justifies the decision to mount PEACE with its field-of-view radially outward rather than tangentially.Key words. Magnetosheric physics (general or miscellaneous) Space plasma physics (spacecraft sheaths, wakes, charging)

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Spacecraft-Charging Mitigation of a High-Power Electron Beam Emitted by a Magnetospheric Spacecraft: Simple Theoretical Model for the Transient of the Spacecraft Potential

Journal of Geophysical Research Space Physics ◽

10.1029/2017ja024926 ◽

2018 ◽

Vol 123 (8) ◽

pp. 6424-6442 ◽

Cited By ~ 8

Author(s):

F. Lucco Castello ◽

G. L. Delzanno ◽

J. E. Borovsky ◽

G. Miars ◽

O. Leon ◽

...

Keyword(s):

Electron Beam ◽

Theoretical Model ◽

High Power ◽

Spacecraft Charging ◽

Simple Theoretical Model ◽

Spacecraft Potential

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Ion bulk speeds and temperatures in the diamagnetic cavity of comet 67P

10.5194/egusphere-egu21-4043 ◽

2021 ◽

Author(s):

Sofia Bergman ◽

Gabriella Stenberg Wieser ◽

Martin Wieser ◽

Fredrik Leffe Johansson ◽

Erik Vigren ◽

...

Keyword(s):

Energy Spectrum ◽

Low Energy ◽

High Time Resolution ◽

Langmuir Probes ◽

Ion Distribution ◽

Strongly Coupled ◽

Neutral Particles ◽

Spacecraft Potential ◽

Impedance Probe ◽

Comet 67P

The formation and maintenance of the diamagnetic cavity around comets is a debated subject. For active comets such as 1P/Halley, the ion-neutral drag force is suggested to balance the outside magnetic pressure at the cavity boundary, but measurements made by Rosetta at the intermediately active comet 67P/Churyumov-Gerasimenko indicate that the situation might be different at less active comets. Measurements from the Langmuir probes and the Mutual Impedance Probe on board Rosetta, as well as modelling efforts, show ion velocities significantly above the velocity of the neutral particles, indicating that the ions are not as strongly coupled to the neutrals at comet 67P.In this study we use low-energy high time resolution data from the Ion Composition Analyzer (ICA) on Rosetta to determine the bulk speeds and temperatures of the ions inside the diamagnetic cavity of comet 67P. The interpretation of the low-energy data is not straight forward due to the complicated influence of the spacecraft potential, but a newly developed method utilizing simulations with the Spacecraft Plasma Interaction Software (SPIS) software makes it possible to extract the original properties of the ion distribution. We use SPIS to model the influence of the spacecraft potential on the energy spectrum of the ions, and fit the energy spectrum sampled by ICA to the simulation results. This gives information about both the bulk speed and temperature of the ions.The results show bulk speeds of 5-10 km/s, significantly above the speed of the neutral particles, and temperatures of 0.7-1.6 eV. The major part of this temperature is attributed to ions being born at different locations in the coma, and could hence be considered a dispersion rather than a temperature in the classical sense. The high bulk speeds support previous results, indicating that the collisional coupling between ions and neutrals is weak inside the diamagnetic cavity.

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PICASSO: The Golden CubeSat

10.5194/egusphere-egu21-15865 ◽

2021 ◽

Author(s):

Noel Baker ◽

Michel Anciaux ◽

Philippe Demoulin ◽

Didier Fussen ◽

Didier Pieroux ◽

...

Keyword(s):

Electron Temperature ◽

Plasma Density ◽

Space Science ◽

Lessons Learned ◽

Vertical Profiles ◽

Proof Of Concept ◽

Scientific Instruments ◽

The Earth ◽

Spacecraft Potential

Led by the Belgian Institute for Space Aeronomy, the ESA-backed mission PICASSO (PICo-Satellite for Atmospheric and Space Science Observations) successfully launched its gold-plated satellite on an Arianespace Vega rocket in September 2020. PICASSO is a 3U CubeSat mission in collaboration with VTT Technical Research Center of Finland Ltd, AAC Clyde Space Ltd. (UK), and the CSL (Centre Spatial de Li&#232;ge), Belgium. The commissioning of the two onboard scientific instruments is currently ongoing; once they are operational, PICASSO will be capable of providing scientific measurements of the Earth&#8217;s atmosphere. VISION, proposed by BISA and developed by VTT, will retrieve vertical profiles of ozone and temperature by observing the Earth's atmospheric limb during orbital Sun occultation; and SLP, developed by BISA, will measure in situ plasma density and electron temperature together with the spacecraft potential.Serving as a groundbreaking proof-of-concept, the PICASSO mission has taught valuable lessons about the advantages of CubeSat technology as well as its many complexities and challenges. These lessons learned, along with preliminary measurements from the two instruments, will be presented and discussed.

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Centrifugal acceleration in the magnetotail lobes

Annales Geophysicae ◽

10.5194/angeo-28-569-2010 ◽

2010 ◽

Vol 28 (2) ◽

pp. 569-576 ◽

Cited By ~ 43

Author(s):

H. Nilsson ◽

E. Engwall ◽

A. Eriksson ◽

P. A. Puhl-Quinn ◽

S. Arvelius

Keyword(s):

Cumulative Effect ◽

Field Measurements ◽

Centrifugal Acceleration ◽

Velocity Change ◽

Data Set ◽

Ion Outflow ◽

Velocity Increase ◽

Average Value ◽

Spacecraft Potential ◽

Total Velocity

Abstract. Combined Cluster EFW and EDI measurements have shown that cold ion outflow in the magnetospheric lobes dominates the hydrogen ion outflow from the Earth's atmosphere. The ions have too low kinetic energy to be measurable with particle instruments, at least for the typical spacecraft potential of a sunlit spacecraft in the tenuous lobe plasmas outside a few RE. The measurement technique yields both density and bulk velocity, which can be combined with magnetic field measurements to estimate the centrifugal acceleration experienced by these particles. We present a quantitative estimate of the centrifugal acceleration, and the velocity change with distance which we would expect due to centrifugal acceleration. It is found that the centrifugal acceleration is on average outward with an average value of about of 5 m s−2. This is small, but acting during long transport times and over long distances the cumulative effect is significant, while still consistent with the relatively low velocities estimated using the combination of EFW and EDI data. The centrifugal acceleration should accelerate any oxygen ions in the lobes to energies observable by particle spectrometers. The data set also put constraints on the effectiveness of any other acceleration mechanisms acting in the lobes, where the total velocity increase between 5 and 19 RE geocentric distance is less than 5 km s−1.

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Multineedle Langmuir Probe Operation and Acute Probe Current Susceptibility to Spacecraft Potential

IEEE Transactions on Plasma Science ◽

10.1109/tps.2019.2906377 ◽

2019 ◽

Vol 47 (8) ◽

pp. 3816-3823

Author(s):

Magnus F. Ivarsen ◽

Bjorn Lybekk ◽

Huy Hoang ◽

Lei Yang ◽

Lasse B. N. Clausen ◽

...

Keyword(s):

Langmuir Probe ◽

Probe Current ◽

Spacecraft Potential

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Remote Sensing of Spacecraft Potential at Geosynchronous Orbit using Secondary and Photo Electrons

AIAA Scitech 2019 Forum ◽

10.2514/6.2019-0311 ◽

2019 ◽

Cited By ~ 6

Author(s):

Miles T. Bengtson ◽

Hanspeter Schaub

Keyword(s):

Remote Sensing ◽

Geosynchronous Orbit ◽

Spacecraft Potential

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Analysis of plasmaspheric plumes: CLUSTER and IMAGE observations

Annales Geophysicae ◽

10.5194/angeo-24-1737-2006 ◽

2006 ◽

Vol 24 (6) ◽

pp. 1737-1758 ◽

Cited By ~ 28

Author(s):

F. Darrouzet ◽

J. De Keyser ◽

P. M. E. Décréau ◽

D. L. Gallagher ◽

V. Pierrard ◽

...

Keyword(s):

High Time Resolution ◽

Total Electron Density ◽

Density Profiles ◽

Total Electron ◽

In Situ Data ◽

Spacecraft Potential ◽

Point Analysis ◽

Boundary Velocity ◽

Electron Density Profiles

Abstract. Plasmaspheric plumes have been routinely observed by CLUSTER and IMAGE. The CLUSTER mission provides high time resolution four-point measurements of the plasmasphere near perigee. Total electron density profiles have been derived from the electron plasma frequency identified by the WHISPER sounder supplemented, in-between soundings, by relative variations of the spacecraft potential measured by the electric field instrument EFW; ion velocity is also measured onboard these satellites. The EUV imager onboard the IMAGE spacecraft provides global images of the plasmasphere with a spatial resolution of 0.1 RE every 10 min; such images acquired near apogee from high above the pole show the geometry of plasmaspheric plumes, their evolution and motion. We present coordinated observations of three plume events and compare CLUSTER in-situ data with global images of the plasmasphere obtained by IMAGE. In particular, we study the geometry and the orientation of plasmaspheric plumes by using four-point analysis methods. We compare several aspects of plume motion as determined by different methods: (i) inner and outer plume boundary velocity calculated from time delays of this boundary as observed by the wave experiment WHISPER on the four spacecraft, (ii) drift velocity measured by the electron drift instrument EDI onboard CLUSTER and (iii) global velocity determined from successive EUV images. These different techniques consistently indicate that plasmaspheric plumes rotate around the Earth, with their foot fully co-rotating, but with their tip rotating slower and moving farther out.

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