High-frequency coherent plasma waves observed in the lower auroral ionosphere

1991 ◽  
Vol 69 (8-9) ◽  
pp. 941-949
Author(s):  
Joëlle Margot ◽  
A. G. McNamara
Keyword(s):  
High Frequency ◽  
Plasma Waves ◽  
Auroral Ionosphere ◽  
Plasma Irregularities ◽  
Coherent Wave ◽  
Wave Forms ◽  
E Region ◽  
Formed Part ◽  
Coherent Plasma ◽  
Probe Measurements

Probe measurements of plasma irregularities in the lower E region during an auroral event showed the presence of coherent wave forms with a wavelength extending down to 35 cm that can be explained by the Farley–Buneman instability. Our results can be interpreted in the frame of recent theories of electron heating by unstable waves. Our data provide experimental evidence that coherent short-wavelength waves can be excited as is assumed in these theories. The measurements were made from rocket AAD-VIIIC-09 (ARIES-A) that formed part of the ARIES campaign for auroral modelling.

scholarly journals In situ measurements of sub-meter plasma waves over low-latitude ionosphere during Leonid-99 meteor storm

2004 ◽  
Vol 22 (6) ◽  
pp. 2033-2036
Author(s):  
S. P. Gupta ◽  
R. Sekar ◽  
Y. B. Acharya
Keyword(s):  
High Frequency ◽  
Plasma Waves ◽  
Plasma Parameters ◽  
Low Latitude ◽  
Scale Size ◽  
Meteor Storm ◽  
Low Latitude Ionosphere ◽  
First Time ◽  
Probe Measurements

Abstract. In situ probe measurements of plasma parameters were carried out on 18 and 20 November 1999 from Sriharikota, India, a low-latitude rocket launching station to investigate the effect of a Leonid meteor storm. Results obtained on plasma waves using a high frequency Langmuir probe are discussed. The characteristics of the sub-meter scale size plasma waves observed for the first time during Leonid meteor storm are presented. Based on the results obtained from both the rocket flights and comparison with the results obtained from previous rocket flights from the same location, it appears these sub-meter waves are associated with intense meteoric activity. A possible mechanism based on the dependence of the meteoric activity and its limitations are discussed.

scholarly journals The generation of non aspect sensitive plasma density irregularities by field aligned drifts in the lower ionosphere

2000 ◽  
Vol 18 (7) ◽  
pp. 799-806 ◽  
Author(s):  
T. R. Robinson ◽  
K. Schlegel
Keyword(s):  
Plasma Density ◽  
Geomagnetic Field ◽  
Lower Ionosphere ◽  
Plasma Waves ◽  
Propagation Direction ◽  
Auroral Ionosphere ◽  
Wave Propagation Direction ◽  
Threshold Conditions ◽  
E Region ◽  
Collisional Heating

Abstract. A theory of the generation of plasma density irregularities with virtually no aspect sensitivity, in the lower ionosphere at high latitudes, by electron drifts aligned with the geomagnetic field, is presented. The theory is developed through fluid equations in which the destabilising mechanism involves positive feedback from electron collisional heating. When field aligned electron drift speeds exceed a few km s-1, this effect destabilises waves with wavelengths in excess of a few tens of metres in the lower E-region, where collisional effects are sufficiently large. Furthermore, the threshold conditions are almost independent of the wave propagation direction and the unstable waves propagate at speeds well below the ion acoustic speed. The role that this new instability may play in recent radar backscatter observations of short scale irregularities propagating in directions close to that of the geomagnetic field, in the lower E-region is also considered.Key words: Ionosphere (auroral ionosphere; ionospheric irregularities; plasma waves and instabilities)

scholarly journals Velocities of auroral coherent echoes at 12 and 144 MHz

2002 ◽  
Vol 20 (10) ◽  
pp. 1647-1661 ◽  
Author(s):  
A. V. Koustov ◽  
D. W. Danskin ◽  
M. V. Uspensky ◽  
T. Ogawa ◽  
P. Janhunen ◽  
...  
Keyword(s):  
Electric Field ◽  
Plasma Waves ◽  
Auroral Ionosphere ◽  
F Region ◽  
Radar Systems ◽  
Radar Echoes ◽  
E Region ◽  
Ionospheric Electric Field ◽  
Coherent Radar ◽  
Eiscat Measurements

Abstract. Two Doppler coherent radar systems are currently working at Hankasalmi, Finland, the STARE and CUTLASS radars operating at ~144 MHz and ~12 MHz, respectively. The STARE beam 3 is nearly co-located with the CUTLASS beam 5, providing an opportunity for echo velocity comparison along the same direction but at significantly different radar frequencies. In this study we consider an event when STARE radar echoes are detected at the same ranges as CUT-LASS radar echoes. The observations are complemented by EISCAT measurements of the ionospheric electric field and electron density behaviour at one range of 900 km. Two separate situations are studied; for the first one, CUTLASS observed F-region echoes (including the range of the EIS-CAT measurements), while for the second one CUTLASS observed E-region echoes. In both cases STARE E-region measurements were available. We show that F-region CUT-LASS velocities agree well with the convection component along the CUTLASS radar beam, while STARE velocities are typically smaller by a factor of 2–3. For the second case, STARE velocities are found to be either smaller or larger than CUTLASS velocities, depending on the range. Plasma physics of E-and F-region irregularities is discussed in attempt to explain the inferred relationship between various velocities. Special attention is paid to ionospheric refraction that is important for the detection of 12-MHz echoes.Key words. Ionosphere (ionospheric irregularities; plasma waves and instabilities; auroral ionosphere)

Time-resolved curling-probe measurements of electron density in high frequency pulsed DC discharges

2015 ◽  
Vol 55 (1) ◽  
pp. 016101 ◽  
Author(s):  
Anil Pandey ◽  
Wataru Sakakibara ◽  
Hiroyuki Matsuoka ◽  
Keiji Nakamura ◽  
Hideo Sugai
Keyword(s):  
Electron Density ◽  
High Frequency ◽  
Time Resolved ◽  
Pulsed Dc ◽  
Probe Measurements

LONG DURATION ECHOES FROM AURORA, METEORS, AND IONOSPHERIC BACK-SCATTER

1953 ◽  
Vol 31 (2) ◽  
pp. 171-181 ◽  
Author(s):  
D. W. R. McKinley ◽  
Peter M. Millman
Keyword(s):  
Long Range ◽  
High Frequency ◽  
The Other ◽  
Very High Frequency ◽  
Long Duration ◽  
E Region ◽  
Very High ◽  
Visual Observations

In the course of the Ottawa meteor program some unusual echoes have been detected on 33 Mc. Echoes from the aurora are discussed and correlated with visual observations. Two mechanisms of radio reflections from the aurora have been proposed but the data here presented are insufficient to favor one over the other. On Aug. 4, 1948, six extremely long duration meteor echoes were observed which may have been due to abnormal ionospheric conditions. From time to time since August, 1948, a weak semipermanent echo has been recorded, usually appearing at a range of about 80 km., and enduring up to an hour. It is suggested that this echo is due to back-scatter from the same sources in the lower E-region that are presumed to be responsible for long-range very high frequency propagation.

scholarly journals 3-D Radar Imaging of E-Region Field-Aligned Plasma Irregularities by Using Multireceiver and Multifrequency Techniques

2018 ◽  
Vol 56 (10) ◽  
pp. 5591-5599 ◽  
Author(s):  
Jenn-Shyong Chen ◽  
Chien-Ya Wang ◽  
Yen-Hsyang Chu ◽  
Ching-Lun Su ◽  
Hiroyuki Hashiguchi
Keyword(s):  
Radar Imaging ◽  
Plasma Irregularities ◽  
E Region

scholarly journals Imaging radar observations and nonlocal theory of large-scale plasma waves in the equatorial electrojet

2002 ◽  
Vol 20 (8) ◽  
pp. 1167-1179 ◽  
Author(s):  
D. L. Hysell ◽  
J. L. Chau
Keyword(s):  
Large Scale ◽  
Equatorial Electrojet ◽  
Plasma Waves ◽  
Radar Data ◽  
Nonlocal Theory ◽  
Main Beam ◽  
Night Time ◽  
Plasma Irregularities ◽  
Background Density ◽  
Spontaneous Regeneration

Abstract. Large-scale (l ~ 1 km) waves in the daytime and night-time equatorial electrojet are studied using coherent scatter radar data from Jicamarca. Images of plasma irregularities within the main beam of the radar are formed using interferometry with multiple baselines. These images are analyzed according to nonlocal gradient drift instability theory and are also compared to nonlinear computer simulations carried out recently by Ronchi et al. (1991) and Hu and Bhattacharjee (1999). In the daytime, the large-scale waves assume a non-steady dynamical equilibrium state characterized by the straining and destruction of the waves by shear and diffusion followed by spontaneous regeneration as predicted by Ronchi et al. (1991). At night, when steep plasma density gradients emerge, slowly propagating large-scale vertically extended waves predominate. Eikonal analysis suggests that these waves are trapped (absolutely unstable) or are nearly trapped (convectively unstable) and are able to tunnel between altitude regions which are locally unstable. Intermediate-scale waves are mainly transient (convectively stable) but can become absolutely unstable in narrow altitude bands determined by the background density profile. These characteristics are mainly consistent with the simulations presented by Hu and Bhattacharjee (1999). A new class of large-scale primary waves is found to occur along bands that sweep westward and downward from high altitudes through the E-region at twilight.Key words. Ionosphere (equatorial ionosphere; ionospheric irregularities; plasma waves and instabilities)

Coupling between High-Frequency Plasma Waves in Laser-Plasma Interactions

1995 ◽  
Vol 74 (12) ◽  
pp. 2236-2239 ◽  
Author(s):  
M. J. Everett ◽  
A. Lal ◽  
C. E. Clayton ◽  
W. B. Mori ◽  
T. W. Johnston ◽  
...  
Keyword(s):  
Laser Plasma ◽  
High Frequency ◽  
Plasma Waves ◽  
Plasma Interactions ◽  
Laser Plasma Interactions ◽  
High Frequency Plasma ◽  
Frequency Plasma
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