Langmuir probe

Abe, Takumi; Oyama, K.‐I.

doi:10.5047/aisi.010

Cited by 11 publications

(9 citation statements)

References 24 publications

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“…Even so, by looking at the temperature measurements, we note that suspicious fluctuations appear in regions of strong plasma density gradients, such as across EPDs. The electron temperatures from the Langmuir probes are derived assuming that the electrons have a Maxwellian velocity distribution in a coordinate system fixed with respect to the probe (Abe & Oyama, ). In the case of a high‐energy population associated with high‐pressure EPDs, the temperature measurements could be inaccurate since particle distribution significantly deviates from a Maxwellian.…”

Section: Discussionmentioning

confidence: 99%

On the Balance Between Plasma and Magnetic Pressure Across Equatorial Plasma Depletions

et al. 2019

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In magnetized plasmas such as the ionosphere, electric currents develop in regions of strong density gradients to balance the resulting plasma pressure gradients. These currents, usually known as diamagnetic currents decrease the magnetic pressure where the plasma pressure increases, and vice versa. In the low‐latitude ionosphere, equatorial plasma depletions (EPDs) are well known for their steep plasma density gradients and adverse effect on radio wave propagation. In this paper, we use continuous measurements of the magnetic field and electron density from the European Space Agency's Swarm constellation mission to assess the balance between plasma and magnetic pressure across large‐scale EPDs. The analysis is based on the magnetic fluctuations related to diamagnetic currents flowing at the edges of EPDs. This study shows that most of the EPDs detected by Swarm present a decrease of the plasma pressure relative to the ambient plasma. However, EPDs with high plasma pressure are also identified mainly in the vicinity of the South Atlantic magnetic anomaly. From the electron density measurements, we deduce that such an increase in plasma pressure within EPDs might be possible by temperatures inside the EPD as high as twice the temperature of the ambient plasma. Due to the distinct location of the high‐pressure EPDs, we suggest that a possible heating mechanism might be due to precipitation of particle from the radiation belts. This finding corresponds to the first observational evidence of plasma pressure enhancements in regions of depleted plasma density in the ionosphere.

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Section: Discussionmentioning

confidence: 99%

On the Balance Between Plasma and Magnetic Pressure Across Equatorial Plasma Depletions

et al. 2019

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“…Langmuir probes have been widely used in space plasma measurements. They have been flown on a variety of missions over the past 50 years from sounding rockets (Abe & Oyama, 2013; Amatucci et al, 2001; Bering et al, 1973) to large missions like MAVEN (Andersson et al, 2015), Cassini (Gurnett et al, 2004), and Rosetta (Eriksson et al, 2007). Langmuir probes consist of a conductor of simple geometries (sphere, plane, or cylinder).…”

Section: Introductionmentioning

confidence: 99%

A Double Hemispherical Probe for Characterizing and Minimizing the Self‐Wake Effects on Probe Measurements

2020

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Space-borne Langmuir probes generally have a self-wake behind themselves due to supersonic relative velocities (Mach number M > 1) between the spacecraft and ambient plasma ions. Such a wake may create difficulties for correctly measuring plasma characteristics. Here we present a new technique-the Double Hemispherical Probe (DHP) to characterize and minimize the self-wake effects on probe measurements. The DHP consists of two hemispheres that are simultaneously swept with a bias voltage to obtain two independent current-voltage (I-V) curves, which are used to identify the wake effects of the probe. A laboratory DHP model is inserted in plasma flows (M > 10) created in the Colorado Solar Wind Experiment (CSWE) chamber. In this case, the ion current is the ram current collected by the upstream hemisphere of the DHP, leaving an ion wake behind the downstream hemisphere. A wide range of the Debye ratio R D (ratio of the probe radius to electron Debye length) is tested, and it is found that (1) when R D < 1, the electron currents collected by the two hemispheres are similar, indicating a uniform electron density around the probe, and (2) when R D > 1, the electron current collected by the downstream hemisphere becomes lower than the upstream, indicating a reduced electron density in the probe's wake due to the ambipolar electric field effect. In this case, the electron density measured by traditional single Langmuir probes will be underestimated. With the DHP, we can use the upstream hemisphere measurements to minimize the self-wake effects.

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“…The LPs are relatively simple instruments which are immersed into a plasma to measure electron density, N e , and electron temperature, T e . Owing to their simplicity, relatively small weight and low power consumption, LPs have been used on many satellite missions (Boyd, 1965;Abe and Oyama, 2013). Examples are Demeter (Lebreton et al, 2006), Rosetta (Eriksson et al, 2007), and Swarm (Knudsen et al, 2017).…”

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confidence: 99%

Swarm Langmuir Probes' data quality and future improvements

Catapano¹,

Buchert

Qamili³

et al. 2021

Preprint

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Abstract. Swarm is ESA's (European Space Agency) first Earth observation constellation mission, which was launched in 2013 to study the geomagnetic field and its temporal evolution. Two Langmuir Probes (LPs) on board of each of the three Swarm satellites provide very accurate measurements of plasma parameters, which contribute to the the study of the ionospheric plasma dynamics. To maintain a high data quality for scientific and operational applications, the Swarm products are continuously monitored and validated via science-oriented diagnostics. This paper presents an overview of the data quality of the Swarm Langmuir Probes' measurements. The data quality is assessed by analysing short and long data segments, where the latter are selected sufficiently long to consider the impact of the solar activity. Langmuir Probes data have been validated through comparison with numerical models, other satellite missions, and ground observations. Based on the outcomes from quality control and validation activities conduced by ESA, as well as scientific analysis and feedback provided by the user community, the Swarm products are regularly upgraded. In this paper we discuss the data quality improvements introduced with the latest baseline, and how the data quality is influenced by the solar cycle. The main anomaly affecting the LP measurements is described, as well as possible improvements to be implemented in future baselines.

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Langmuir probe

Cited by 11 publications

References 24 publications

On the Balance Between Plasma and Magnetic Pressure Across Equatorial Plasma Depletions

On the Balance Between Plasma and Magnetic Pressure Across Equatorial Plasma Depletions

A Double Hemispherical Probe for Characterizing and Minimizing the Self‐Wake Effects on Probe Measurements

Swarm Langmuir Probes' data quality and future improvements

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