scholarly journals Saturation effects of the lower ionosphere based on two‐dimensional HF heating model

2017 ◽  
Vol 122 (1) ◽  
pp. 874-890 ◽  
Author(s):  
Qi Cheng ◽  
Li‐xin Guo ◽  
Hui‐min Li ◽  
Jiang‐ting Li
Keyword(s):  
Lower Ionosphere ◽  
Two Dimensional ◽  
Heating Model ◽  
Hf Heating ◽  
Saturation Effects

VLF-HF heating of the lower ionosphere and ELF wave generation

1992 ◽  
Vol 19 (4) ◽  
pp. 61-64 ◽  
Author(s):  
Y. N. Taranenko ◽  
U. S. Inan ◽  
T. F. Bell
Keyword(s):  
Lower Ionosphere ◽  
Wave Generation ◽  
Hf Heating

scholarly journals ELF wave generation in the ionosphere using pulse modulated HF heating: initial tests of a technique for increasing ELF wave generation efficiency

1999 ◽  
Vol 17 (6) ◽  
pp. 759-769 ◽  
Author(s):  
R. Barr ◽  
P. Stubbe ◽  
M. T. Rietveld
Keyword(s):  
Fundamental Frequency ◽  
Lower Ionosphere ◽  
Wave Generation ◽  
Cooling Time ◽  
Ionospheric Currents ◽  
Time Constants ◽  
Radio Science ◽  
Heating And Cooling ◽  
Hf Heating ◽  
Even Harmonics

Abstract. This paper describes the results of a preliminary study to determine the effective heating and cooling time constants of ionospheric currents in a simulated modulated HF heating, `beam painting' configuration. It has been found that even and odd harmonics of the fundamental ELF wave used to amplitude modulate the HF heater are sourced from different regions of the ionosphere which support significantly different heating and cooling time constants. The fundamental frequency and its odd harmonics are sourced in a region of the ionosphere where the heating and cooling time constants are about equal. The even harmonics on the other hand are sourced from regions of the ionosphere characterised by ratios of cooling to heating time constant greater than ten. It is thought that the even harmonics are sourced in the lower ionosphere (around 65 km) where the currents are much smaller than at the higher altitudes around 78 km where the currents at the fundamental frequency and odd harmonics maximise.Key words. Electromagnetics (antennae) · Ionosphere (active experiments) · Radio science (non linear phenomena)

scholarly journals Magnetospheric injection of ELF/VLF waves with modulated or steered HF heating of the lower ionosphere

2011 ◽  
Vol 116 (A6) ◽  
pp. n/a-n/a ◽  
Author(s):  
M. B. Cohen ◽  
U. S. Inan ◽  
D. Piddyachiy ◽  
N. G. Lehtinen ◽  
M. Gołkowski
Keyword(s):  
Lower Ionosphere ◽  
Hf Heating ◽  
Vlf Waves

scholarly journals Excitation of Alfvén waves by modulated HF heating of the ionosphere, with application to FAST observations

2002 ◽  
Vol 20 (1) ◽  
pp. 57-67 ◽  
Author(s):  
E. Kolesnikova ◽  
T. R. Robinson ◽  
J. A. Davies ◽  
D. M. Wright ◽  
M. Lester
Keyword(s):  
Electric Field ◽  
Scalar Potential ◽  
Lower Ionosphere ◽  
Alfven Wave ◽  
Thermal Electron ◽  
Strong Electron ◽  
Inner Magnetosphere ◽  
Hf Heating ◽  
Parallel Current ◽  
Current Electric Field

Abstract. During the operation of the EISCAT high power facility (heater) at Tromsø, Norway, on 8 October 1998, the FAST spacecraft made electric field and particle observations in the inner magnetosphere at 0.39 Earth radii above the heated ionospheric region. Measurements of the direct current electric field clearly exhibit oscillations with a frequency close to the modulated frequency of heater ( ~ 3 Hz) and an amplitude of ~ 2 - 5 mV m-1. Thermal electron data from the electrostatic analyser show the modulation at the same frequency of the downward electron fluxes. During this period the EISCAT UHF incoherent scatter radar, sited also at Tromsø, measured a significant enhancement of the electron density in E-layer up to 2 · 1012 m-3. These observations have prompted us to make quantitative estimates of the expected pulsations in the inner magnetosphere caused by the modulated HF heating of lower ionosphere. Under the conditions of the strong electron precipitation in the ionosphere, which took place during the FAST observations, the primary current caused by the perturbation of the conductivity in the heated region is closed entirely by the parallel current which leaks into the magnetosphere. In such circumstances the conditions at the ionosphere-magnetosphere boundary are most favourable for the launching of an Alfvén wave: it is launched from the node in the gradient of the scalar potential which is proportional to the parallel current. The parallel electric field of the Alfvén wave is significant in the region where the electron inertial length is of order of the transverse wavelength of the Alfvén wave or larger and may effectively accelerate superthermal electrons downward into the ionosphere.Key words. Ionosphere (active experiments; ionosphere – magnetosphere interactions; particle acceleration)

Revised models for attenuation of Modified Mercalli intensity in New Zealand earthquakes

2005 ◽  
Vol 38 (4) ◽  
pp. 185-214 ◽  
Author(s):  
D. J. Dowrick ◽  
D. A. Rhoades
Keyword(s):  
New Zealand ◽  
South China ◽  
Two Dimensional ◽  
Algebraic Form ◽  
Attenuation Model ◽  
Source Distance ◽  
Attenuation Rate ◽  
Intensity Saturation ◽  
Additional Improvement ◽  
Saturation Effects

This paper presents simple two-dimensional models for attenuation of Modified Mercalli intensity in New Zealand earthquakes, which improve upon the models published by the present authors in 1999. First, the models now ensure that the attenuation functions in the two orthogonal directions converge to the same value at zero source distance. Secondly, an improved fit has been achieved through a modification of the algebraic form of the log distance term in the attenuation function. An additional improvement is the completion of the attenuation model for Deep events (hc ⩾ 70 km) in the subducting Pacific plate, which was not fully dealt with in our previous paper. Intensity saturation effects are demonstrated. A comparison is made between our New Zealand model and one for the intraplate region of South China where the attenuation rate is considerably lower.

ELF and VLF wave generation by modulated HF heating of the current carrying lower ionosphere

1982 ◽  
Vol 44 (12) ◽  
pp. 1123-1135 ◽  
Author(s):  
P Stubbe ◽  
H Kopka ◽  
M.T Rietveld ◽  
R.L Dowden
Keyword(s):  
Lower Ionosphere ◽  
Wave Generation ◽  
Hf Heating
Sign in / Sign up

Export Citation Format

Share Document