Analysis of incoherent scatter during ionospheric heating near the fifth electron gyrofrequency

Abstract. During an ionospheric heating campaign carried out at the European Incoherent Scatter Scientific Association (EISCAT), the ultra high frequency incoherent scatter (IS) radar observed a systematic variation in the altitude of the high-frequency enhanced plasma line (HFPL), which behaves depending on the pump frequency. Specifically, the HFPL altitude becomes lower when the pump lies above the 5th gyro-harmonic. The analysis shows that the enhanced electron temperature plays a decisive role in the descent in the HFPL altitude. That is, on the traveling path of the enhanced Langmuir wave, the enhanced electron temperature can only be matched by the low electron density at a lower altitude so that the Bragg condition can be satisfied, as expected from the dispersion relation of Langmuir wave.

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Analysis of Observations near the Fourth Electron Gyrofrequency Heating Experiment in EISCAT

Universe ◽

10.3390/universe7060191 ◽

2021 ◽

Vol 7 (6) ◽

pp. 191

Author(s):

Zeyun Li ◽

Hanxian Fang ◽

Hongwei Gong ◽

Zhe Guo

Keyword(s):

Electron Temperature ◽

Electron Density ◽

Parametric Instability ◽

Density Fluctuations ◽

Lower Hybrid ◽

Langmuir Waves ◽

Ionospheric Heating ◽

Superthermal Electron ◽

Temperature Electron ◽

Electron Gyrofrequency

We present the observations of the artificial ionospheric heating experiment of EISCAT (European Incoherent Scatter Scientific Association) on 22 February 2012 in Tromsø, Norway. When the pump is operating near the fourth electron gyrofrequency, the UHF radar observation shows some strong enhancements in electron temperature, electron density, ion line, and the outshifted plasma lines. Based on some existing theories, we find the following: first, Langmuir waves scattering off lower hybrid density fluctuations and strong Langmuir turbulence (SLT) in the Zakharov model cannot completely explain the outshifted plasma lines, but the data suggest that this phenomenon is related to the cascade of the pump wave and should be researched further; second, the spatiotemporal consistency between the enhancement in electron density/electron temperature reaches up to three to four times that of the undisturbed state and HF-enhanced ion lines (HFILs) suggest that SLT excited by parametric instability plays a significant role in superthermal electron formation and electron acceleration; third, some enhancements in HFILs and HF-induced plasma lines (HFPLs) are generated by parametric decay instability (PDI) during underdense heating in the third cycle, we suggest that this is due to the existence of a second cut-off in the upper hybrid dispersion relation as derived from a kinetic description.

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History of the Tromsø Ionosphere Heating facility

10.5194/hgss-2021-19 ◽

2021 ◽

Author(s):

Michael T. Rietveld ◽

Peter Stubbe

Keyword(s):

Historical Background ◽

Incoherent Scatter Radar ◽

Max Planck ◽

Ionospheric Heating ◽

Heating Facility ◽

Incoherent Scatter ◽

Scatter Radar ◽

History Of ◽

New Generation ◽

Near Future

Abstract. We present the historical background to the construction of a major ionospheric heating facility near Tromsø, Norway in the 1970s by the Max Planck Institute for Aeronomy and the subsequent operational history to the present. It was built next to the EISCAT incoherent scatter radar facility and in a region with a multitude of diagnostic instruments used to study the auroral region. The facility was transferred to the EISCAT Scientific Association in January 1993 and continues to provide new discoveries in plasma physics and ionospheric and atmospheric science to this day. It is expected that ‘Heating’ will continue operating together with the new generation of incoherent scatter radar, called EISCAT_3D, when it is commissioned in the near future.

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History of EISCAT – Part 4: On the German contribution to the early years of EISCAT

History of Geo- and Space Sciences ◽

10.5194/hgss-7-67-2016 ◽

2016 ◽

Vol 7 (2) ◽

pp. 67-72

Author(s):

Gerhard Haerendel

Keyword(s):

Early Years ◽

Max Planck ◽

Ionospheric Heating ◽

Heating Facility ◽

Incoherent Scatter ◽

Design And Manufacturing ◽

History Of ◽

Max Planck Society ◽

Uhf Radar ◽

German Contribution

Abstract. The decision of the Max Planck Society (MPG) to get involved in the establishment of an incoherent scatter radar in northern Europe was intimately linked to the future of the Max Planck Institute for Aeronomy (MPAe) in Katlenburg-Lindau. Delegates of the MPG played an important role in defining the rules for participation in EISCAT during the period from 1973 to 1975. The "technical" period from 1976 to 1981 was mainly devoted to the development of the UHF transmitter and the klystrons. The latter encountered great difficulties, causing substantial delays. During the same period the ionospheric heating facility was established by MPAe at Ramfjordmoen, Norway. The period following the inauguration in August 1981 saw a great number of changes in the leading personnel. In this context much attention had to be given to taxation rules. Besides continuing hardware problems with the UHF radar, severe problems arose with design and manufacturing of the VHF klystrons, requiring changes of the contractor. However, by fall of 1983 the UHF radar was able to reach the intended operational level. In 1984 important steps were made for archiving and for proper exploitation of the EISCAT data.

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Irregular structures of the F layer at high latitudes during ionospheric heating

Annales Geophysicae ◽

10.1007/s00585-000-1197-1 ◽

2000 ◽

Vol 18 (9) ◽

pp. 1197-1209 ◽

Cited By ~ 7

Author(s):

E. D. Tereshchenko ◽

M. O. Kozlova ◽

O. V. Evstafiev ◽

B. Z. Khudukon ◽

T. Nygrén ◽

...

Keyword(s):

Small Scale ◽

Auroral Ionosphere ◽

Perpendicular Anisotropy ◽

Ionospheric Heating ◽

Incoherent Scatter ◽

Active Experiments ◽

F Region ◽

Irregular Structures ◽

Heating Region ◽

Region Plasma

Abstract. Results on heating the ionospheric F region above Tromsø, Norway are presented. The ionosphere was monitored by satellite tomography and amplitude scintillation methods as well as the EISCAT incoherent scatter radar. No effect of heating was observed in the daytime. In the evening and in the pre-midnight sector, noticeable tilts of the F region were observed during heating periods. The tilts overlapped the heating cone, where the electron density decreased and irregularities exceeding 10 km in size appeared. Between the heating periods the F layer was restored to its horizontal shape. The anisotropic parameters of small-scale irregularities with scale lengths of hundreds of metres were also determined. It was found that the perpendicular anisotropy points in the direction of F region plasma flow. In some cases the results can be explained by assuming that the small-scale irregularities were generated within the heating cone and drifted out of the heating region where they were subsequently observed.Key words: Ionosphere (active experiments; auroral ionosphere; ionospheric irregularities)

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