Absolute electron density measurements in the equatorial ionosphere

Investigation of Earth's mesosphere using sounding rockets equipped with a myriad of instruments has been a highly active field in the last 2 decades. This paper presents data from three separate instruments: an RF impedance probe, a DC fixed bias Langmuir probe, and an electric field probe, that were flown on a mesospheric sounding rocket flight investigating the presence of charged dust within and/or around a sporadic metal layer. The combined data set indicates a case of payload surface charging, the causes of which are investigated within this paper. A generic circuit model is developed to analyze payload charging and behavior of Langmuir‐type instruments. The application of this model to the rocket payload indicates that the anomalous charging event was an outcome of triboelectrification of the payload surface from neutral dust particles present in the Earth's mesosphere. These results suggest caution in interpreting observations from the Langmuir class of instrumentation within dusty environments.

Section: Sudden Atom Layer Investigationmentioning

confidence: 99%

Observations of triboelectric charging effects on Langmuir‐type probes in dusty plasma

Barjatya¹,

Swenson²

2006

“…We now investigate the perturbations in plasma density associated with the two-stream waves and relate this measurement to the potential differences that we have just discussed. The most reliable measurement of the density perturbation of the waves was from the plasma frequency probe [Baker et al, 1985]. Fortuitously, because the rocket was traveling at almost (but not quite) the same velocity as the waves, there was adequate time for the instrument to lock onto the local upper hybrid frequency within the crests and troughs of the meter scale waves, from which the local plas•na density was determined.…”

Section: -Upleg Two-stream Wavesmentioning

confidence: 99%

Electric field and plasma density measurements in the strongly driven daytime equatorial electrojet: 2. Two‐stream waves

Pfaff¹,

Kelley²,

Kudeki³

et al. 1987

Both primary and secondary two‐stream (Farley‐Buneman) waves have been detected by in situ electric field and plasma density probes in the strongly driven daytime equatorial electrojet over Peru. Simultaneous Jicamarca radar observations showed strong vertical and oblique 3‐m type 1 echoes, also indicative of the two‐stream mechanism. The rocket data show the two‐stream region on the topside of the unstable layer to be situated between 103 and 111 km where the electron current was the strongest. This region was characterized by broadband plasma oscillations extending past 1 kHz in the rocket frame. Furthermore, above 106.5 km, where the electron density gradient was stable, a layer of laminarlike, horizontally propagating two‐stream waves was detected. These waves were strongest near 108 km, the altitude where previous measurements have shown the electrojet current over Peru to be strongest. The peak rocket frame frequency of these waves was 25 Hz, and the observed broadband electric field and plasma density amplitudes were 2 mV/m and 1–2% rms, respectively. The electric field amplitudes were likely attenuated by a spatial filtering effect and may have been several times higher. The data suggest that these waves had phase velocities comparable to the electron drift velocity (≃500 m/s) and peak wavelengths (2–3 m) that agree with kinetic theory predictions. Distinct vertically oriented waves which may have been generated by a mode coupling process were also observed by the rocket in this region, in agreement with the simultaneous radar observations. Below the laminar two‐stream layer, in the region of the large‐scale, gradient drift driven horizontal electric fields, secondary two‐stream waves were observed that were driven by localized δE × B plasma drifts. The amplitudes of the horizontally propagating kilometer scale waves were clearly strong enough (10–15 mV/m) to drive vertically oriented secondary two‐stream (type 1) waves, as proposed by Sudan et al. (1973) and observed by the Jicamarca radar between roughly 103 and 106 km. Below 103 km, secondary two‐stream waves could not be generated because ψ (the ratio of the ion and electron collision frequencies to their gyro frequencies) becomes large, despite the fact that the observed large‐scale wave amplitudes remained strong at the lower altitudes. Observations of “flat‐topped” waveforms of the large horizontal electric field structures suggest that secondary two‐stream phase velocities may be saturated because of a limitation of the driving electric fields rather than a process intrinsic to the two‐stream instability itself.

“…This paper con- At the two altitudes indicated, the density profile has been detrended and Fourier analyzed to obtain the spectra at right. an RF probe provided by Utah State University measured the absolute electron density and also produced spectra of the intermediate-scale density fluctuations [Baker et al, 1969[Baker et al, , 1985, and a particle detector provided by the University of Illinois measured keV electrons. Many more details of the rocket instrumentation, the conditions of the launches, and the ground-based instrumentation are reported elsewhere in this issue (paper 1).…”

Section: Introductionmentioning

confidence: 99%

The generation of kilometer scale irregularities in equatorial spread F

LaBelle

Kelley

1986

Two rockets launched into spread F during March 1983 show that the intermediate-scale spectrum of density irregularities sometimes exhibits a knee near 1 km scale length. This result confirms previous reports which are reviewed. Two different nonlinear theories of spread F turbulence are studied here and shown to be consistent with the experimental spectra when the knee is observed. Also, the existence or nonexistence of the knee may be effected by two linear mechanisms: the injection of kilometer scale turbulence at the steepened walls of spread F bubbles and the nonlocal role of the compressible E region in the development of spread F. This spectral feature, which seems to be associated with the most turbulent state of equatorial spread F, has not yet been identified in computer simulations. centrates on the characteristics of the medium and intermediate wavelength ranges: wavelengths between 100 m and 10 km. Companion papers treat some of the global aspects [Argo and Kelley, this issue], the long wavelengths [Kelley et al., this issue] (hereinafter referred to as paper 1), and the transitional and short-wavelength regime [LaBelle et al., this issue]. Also among the companion papers is a study of the scintillations associated with the medium-and intermediate-scale irregularities, including a discussion concerning the relation between the scintillation observations and the rocket observations [Basu et al., this issue].Equatorial spread F irregularities are highly field aligned, and therefore the spread F turbulence is effectively twodimensional. At most wavelengths the spectrum is probably isotropic in that plane, but at some scale length the spectrum must become anisotropic, reflecting the fact that the ionosphere is much more narrowly bounded vertically than horizontally. Therefore one must take extra caution when comparing spectra o. btained by different experimental techniques, especially at scale sizes approaching the dimensions of the F region.Observations of the spectrum of spread F irregularities in the range from 100 m to 10 km basically fall into two categories. First, satellite-borne probes and ground-based observations of phase and amplitude scintillations allow measurement of the horizontal wave number spectrum. Very frequently, the intermediate-scale spectrum observed by these techniques takes the form of a power law; in other words, the power spectral density is proportional to some power of the wave number: lk oc k n. The quantity n is called the spectral index. Satellite experiments consistently observe a power law spectrum of density irregularities, with the spectral index varying from -1 to -3 [Dyson et al., 1974; Valladares et al., 1983; Livingston et al., 1981; Kelley and McClure, 1981]. There is also evidence from the satellite data that in this range of wave numbers the spectrum of electric field irregularities is also characterized by a spectral index of roughly -2 [Kelley and Mozer, 1972]. Scintillation observations imply a spectral index consistent with the in situ results [Basu et al.,...