Plasma‐density measurements by microwave interferometry and Langmuir probes in an rf discharge

1993 ◽  
Vol 64 (1) ◽  
pp. 19-25 ◽  
Author(s):  
G. Neumann ◽  
U. Bänziger ◽  
M. Kammeyer ◽  
M. Lange
Keyword(s):  
Plasma Density ◽  
Rf Discharge ◽  
Langmuir Probes ◽  
Density Measurements ◽  
Microwave Interferometry

scholarly journals Solar flares observed by Rosetta at comet 67P/Churyumov-Gerasimenko

2019 ◽  
Vol 630 ◽  
pp. A49 ◽  
Author(s):  
N. J. T. Edberg ◽  
F. L. Johansson ◽  
A. I. Eriksson ◽  
D. J. Andrews ◽  
R. Hajra ◽  
...  
Keyword(s):  
Plasma Density ◽  
Solar Flares ◽  
Langmuir Probe ◽  
Extreme Ultraviolet ◽  
Vantage Point ◽  
Spectral Model ◽  
Time Of Arrival ◽  
Observable Effect ◽  
Density Measurements ◽  
Comet 67P

Context. The Rosetta spacecraft made continuous measurements of the coma of comet 67P/Churyumov-Gerasimenko (67P) for more than two years. The plasma in the coma appeared very dynamic, and many factors control its variability. Aims. We wish to identify the effects of solar flares on the comet plasma and also their effect on the measurements by the Langmuir Probe Instrument (LAP). Methods. To identify the effects of flares, we proceeded from an existing flare catalog of Earth-directed solar flares, from which a new list was created that only included Rosetta-directed flares. We also used measurements of flares at Mars when at similar longitudes as Rosetta. The flare irradiance spectral model (FISM v.1) and its Mars equivalent (FISM-M) produce an extreme-ultraviolet (EUV) irradiance (10–120 nm) of the flares at 1 min resolution. LAP data and density measurements obtained with the Mutual Impedence Probe (MIP) from the time of arrival of the flares at Rosetta were examined to determine the flare effects. Results. From the vantage point of Earth, 1504 flares directed toward Rosetta occurred during the mission. In only 24 of these, that is, 1.6%, was the increase in EUV irradiance large enough to cause an observable effect in LAP data. Twenty-four Mars-directed flares were also observed in Rosetta data. The effect of the flares was to increase the photoelectron current by typically 1–5 nA. We find little evidence that the solar flares increase the plasma density, at least not above the background variability. Conclusions. Solar flares have a small effect on the photoelectron current of the LAP instrument, and they are not significant in comparison to other factors that control the plasma density in the coma. The photoelectron current can only be used for flare detection during periods of calm plasma conditions.

First results from plasma density measurements in the FTU tokamak by means of a two-frequency pulsed time-of-flight refractometer

2012 ◽  
Vol 38 (4) ◽  
pp. 343-351 ◽  
Author(s):  
V. G. Petrov ◽  
A. Yu. Malyshev ◽  
V. K. Markov ◽  
A. A. Petrov ◽  
F. Avino ◽  
...  
Keyword(s):  
Plasma Density ◽  
Time Of Flight ◽  
Density Measurements ◽  
First Results

scholarly journals Stratification observed by the in situ plasma density measurements from the Swarm satellites

2020 ◽  
Vol 38 (2) ◽  
pp. 517-526
Author(s):  
Xiuying Wang ◽  
Wanli Cheng ◽  
Zihan Zhou ◽  
Dehe Yang ◽  
Jing Cui ◽  
...  
Keyword(s):  
Plasma Density ◽  
Continuous Distribution ◽  
Direct Analysis ◽  
Density Measurements ◽  
Equatorial Ionization Anomaly ◽  
Swarm Satellites ◽  
Plasma Peak ◽  
First Time ◽  
New Discovery

Abstract. The stratification phenomenon is investigated using the simultaneous in situ plasma density measurements obtained by the Swarm satellites orbiting at different altitudes above the F2 peak. For the first time, the continuous distribution morphology and the exact locations are obtained for the nighttime stratification, which show that the stratification events are centered at the EIA (equatorial ionization anomaly) trough and extend towards the two EIA crests, with the most significant part being located at the EIA trough. Another new discovery is the stratification in southern mid-latitudes; stratification events in this region are located on a local plasma peak sandwiched by two lower density strips covering all the longitudes. The formation mechanism of the stratification for the two latitudinal regions is discussed, but the stratification mechanism in southern mid-latitudes remains an unsolved problem. Highlights. This paper addresses the following: first application of in situ plasma densities for the direct analysis of the stratification in F2 layer, refined features of the exact location and continuous morphology for the stratification phenomenon, a new discovery of stratification covering all longitudes in southern mid-latitudes.

scholarly journals Ionospheric Plasma Density Measurements by Swarm Langmuir Probes: Limitations and possible Corrections

2019 ◽  
Author(s):  
Piero Diego ◽  
Igino Coco ◽  
Igor Bertello ◽  
Maurizio Candidi ◽  
Pietro Ubertini
Keyword(s):  
Electron Density ◽  
Ionospheric Plasma ◽  
Operating Mode ◽  
Plasma Sheath ◽  
Langmuir Probes ◽  
Plasma Parameters ◽  
Density Measurements ◽  
Voltage Ripple ◽  
Electron Density And Temperature ◽  
Ionospheric Plasma Density

Abstract. The ESA Swarm constellation includes three satellites, which have been observing the Earth's ionosphere since November 2013, following polar orbits. The main ionospheric plasma parameters, such as electron density and temperature, are measured by means of Langmuir probes (Lps); electron density measurements, in particular, are nowadays largely considered as qualitatively reliable, and have been used in several published papers to date. In this work, we aim to discuss how some technical characteristics of Swarm Lps, such as their size and location on board the satellites, as well as the operational setup of the instruments, could lead to limitations in their accuracy if one underestimates the influence of satellite proximity, and the larger extension of the plasma sheath surrounding the probes due to the operational point of the voltage ripple. Two specific corrections are proposed for the assessment and possible mitigation of such effects. Finally, a comparison is made with electron density measurements from CSES-01 mission, which relies on Langmuir probes as well, whose geometry and operating mode are standard.

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