The Thermal Ion Dynamics Experiment and Plasma Source Instrument

Moore, T. E.; Chappell, C. R.; Chandler, M. O.; Fields, S. A.; Pollock, C. J.; Reasoner, D. L.; Young, D. T.; Burch, J. L.; Eaker, N.; Waite, J. H.; McComas, D. J.; Nordholdt, J. E.; Thomsen, M. F.; Berthelier, J. J.; Robson, Robert

doi:10.1007/bf00751337

Cited by 102 publications

(66 citation statements)

References 10 publications

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“…Also, the minimum of this index occurs for potentials close to the critical potential (for which N 0 =N ) which typically lies in the range 2-6 V, the higher value corresponding to the solar wind. This range agrees well with the capabilities of existing active potential control devices as employed, for example, on Polar (PSI experiment, Moore et al (1995), with a bias potential ∼2 V) and Cluster (ASPOC experiment, Torkar et al, 2001, with a bias potential ∼3-7 V). Such devices basically emit a positive ion beam to counter the positive charge and manage to dynamically stabilize the potential to values close to the bias value.…”

Section: Resultssupporting

confidence: 85%

Spacecraft potential effects on electron moments derived from a perfect plasma detector

Génot

Schwartz

2004

Ann. Geophys.

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Abstract.A complete computation of the effect of the spacecraft potential on electron moments is presented. We adopt the perfect detector concept to estimate how measured density, velocity and temperature are affected by the constraints imposed by the detector, such as the finite lower energy cutoff and the spacecraft potential. We investigate the role of the potential in different plasma regimes usually crossed by satellites. It appears that the solar wind is the region where the moments are most compromised, as the particle temperature is low. To a lesser extent the moments calculated in the magnetosheath may also deviate from the real moments, displaying up to 40% overestimation for the density under typical detector operation. The analysis allows us to identify a range of spacecraft potential values which minimizes the variation in the estimation; it is found that it corresponds to the common value adopted by potential controlling experiments.

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Section: Resultssupporting

confidence: 85%

Spacecraft potential effects on electron moments derived from a perfect plasma detector

Génot

Schwartz

2004

Ann. Geophys.

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“…We present clear evidence of well defined transverse ion heating near Polar apogee in which the heated ions take the form of toroids or "donuts" in velocity space with a sharp low-energy cutoff to the distribution. We use data from the TIDE (see [Moore et al, 1995] for instrument details) and TIMAS (see [Shelley et al, 1995]) for instrument details) mass spectrometers on board the ISTP/Polar spacecraft.…”

Section: Introductionmentioning

confidence: 99%

Toroidal ion distributions observed at high altitudes equatorward of the cusp

Huddleston

Pollock

Wüest

et al. 2000

Geophysical Research Letters

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Abstract.We examine events where the TIDE and TIMAS ion instruments on board the Polar spacecraft have observed transversely accelerated ions (TAI) at altitudes greater than 20,000 km. We report both H + and O + populations that have been heated perpendicular to the local B field but that also have a sharp low-energy cutoff to the distribution occurring at 20-100 eV. Analysis of an event on 21 April 1996 indicates that the formation of ion toroids may be related to solitary structures or low frequency wave pulses observed during the event. We address some of the implications of using time (as opposed to frequency) domain techniques to analyze wave/particle energization events.

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“…By pertbrming numerical integrations of moments of the TIDE ion distribution function in velocity space, the density and velocity of the ions are determined. TIDE is able to observe plasma in the highaltitude magnetospheric polar cap by operating in conjunction with the Plasma Source Instrument (PSI), a plasma contactor [Comfort et al, 1998;Moore et al, 1995] that reduces the electric potential on the spacecraft from tens of volts to -2.0 V. The average spacecraft potential in the polar cap at apogee without PSI operating is -25 V, which is enough to shield out nearly all of the H+ ions and a significant fraction of the O+ ions. We could study some of the O+ without PSI operating, but then the data set would be biased toward times when the O+ energy is high.…”

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confidence: 99%

Solar wind influence on the oxygen content of ion outflow in the high‐altitude polar cap during solar minimum conditions

Elliott

Comfort²,

Craven

et al. 2001

J. Geophys. Res.

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Abstract. We correlate solar wind and interplanetary magnetic field (IMF) properties with the properties of O+ and H+ during early 1996 (solar minimum) at altitudes between 5.5 and 8.9 R E geocentric using the Thermal Ion Dynamics Experiment (TIDE) on the Polar satellite. Throughout the high-altitude polar cap we observe H+ to be more abundant than O+. O+ is found to be more abundant at lower latitudes when the solar wind speed is low (and Kp is low), while at higher solar wind speeds (and high Kp), O+ is observed across most of the polar cap. The O+ density and parallel flux are well organized by solar wind dynamic pressure, both increasing with solar wind dynamic pressure. Both the O+ density and parallel flux have positive correlations with both VswBiM F and Esw. No correlation is found between O+ density and IMF Bz, although a nonlinear relationship with IMF By is observed, possibly due to a strong linear correlation with the dynamic pressure. H+ is not as highly correlated with solar wind and IMF parameters, although H+ density and parallel flux are negatively correlated with IMF By and positively correlated with both VswBiM F and Esw. In this solar minimum data set, H+ is dominant, so that contributions of this plasma to the plasma sheet would have very low O+ to H+ ratios.

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The Thermal Ion Dynamics Experiment and Plasma Source Instrument

Cited by 102 publications

References 10 publications

Spacecraft potential effects on electron moments derived from a perfect plasma detector

Spacecraft potential effects on electron moments derived from a perfect plasma detector

Toroidal ion distributions observed at high altitudes equatorward of the cusp

Solar wind influence on the oxygen content of ion outflow in the high‐altitude polar cap during solar minimum conditions

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