Anomalous attenuation of extraordinary waves in the ionosphere heating experiments

Multiple scattering of radio waves by artificial random irregularities HF-induced in the ionosphere F region may cause significant attenuation of both ordinary and extraordinary waves together with common anomalous absorption of ordinary waves due to their non-linear conversion into plasma waves. To demonstrate existence and strength of this effect, direct measurements of attenuation of both powerful pump wave and weak probing waves of extraordinary polarization have been carried out during an experimental campaign on September 6, 7 and 9, 1999 at the Sura heating facility. The attenuation magnitude of extraordinary waves reaches of 1-10 dB over a background attenuation caused by natural irregularities. It is interpreted in the paper on the base of the theory of multiple scattering from the artificial random irregularities with characteristic scale lengths of 0.1-1 km. Simple procedure for determining of irregularity spectrum parameters from the measured attenuation of extraordinary waves has been implemented and some conclusions about the artificial irregularity formation have been obtained.Comment: 17 pages, 9 figure

Parametric instability induced by X-mode Heating at EISCAT

In this paper, we present results of parametric instability induced by X-mode wave heating observed by EISCAT (European Incoherent Scatter Scientific Association) radar at Tromsø, Norway. Three typical X-mode ionospheric heating experiments on October 22, 2013, October 19, 2012 and February 21, 2013 are investigated in details. Both parametric decay instability (PDI) and oscillating two-stream instability (OTSI) are observed during the X-mode heating period. We suggest that the full dispersion relationship of the Langmuir wave can be employed to analyze the X-mode parametric instability excitation. Parallel electric field component of X-mode heating wave can also exceed the parametric instability excitation threshold under certain conditions

Ionospheric gas dynamics of satellites and diagnostic probes

The gas dynamics of interactions of a tenuous ionosphere with moving satellites and probes that have bearings on the diagnostics of the ionosphere are discussed. Emphasis is on the cases where the body is moving at mesothermal speeds, namely intermediate between the thermal speeds of ions and electrons of the ambient ionosphere. Methods of collision-free plasma kinetics with self-consistent field are used. The development of the topics for discussion starts with stationary Langmuir probe which entails the basic mechanism of body-plasma interaction that becomes further intricated as the body moves at a higher and higher speed. Applications of the theory of plasma interaction to meteors which move in the ionosphere are also presented.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43801/1/11214_2004_Article_BF00212707.pd

Acmeological approach to physical education of students of secondary schools in the aspect of personality-oriented training

Purpose : to identify the main ways to use acmeological approach to physical education students of secondary schools. Material : government documents, questionnaire, research scientists, monitoring the activities of teachers-practitioners. Results : identified actual problems of physical education of students. Theoretical aspects and conditions of implementation in a real learning process acmeological approach. The problems of setting goals and objectives to students considering acmeological approach. The approach includes the selection of a modern sports education content. Also, forms, methods and teaching aids that optimize the learning activities of each student. Proposes a system of evaluation of students' achievements based on acmeological approach. Examines the role of physical education of teachers to introduce acmeological approach in the learning process. Conclusions : the main aspects of acmeological approach to the organization of educational process on physical training. It is proposed to develop the content of sports education based on general didactic approaches. Approach that includes four components of social experience. The components of the educational process technology for physical culture. It is proposed to modernize the methods, forms and means of improving the system of assessing students' achievements in an integrated manner

Ionospheric plasma response to HF waves operating at frequencies close to the third harmonic of the electron gyrofrequency

Experimental results concerning European incoherent scatter observations of heater-induced electron temperature enhancements, anomalous absorption of low-power HF probe waves, and the spectrum of stimulated electromagnetic emission (SEE) in the sidebands of a high-power HF electromagnetic wave are presented. For the experiments reported in this paper, an O mode pump wave was transmitted vertically into the F region above Tromsø, Norway, while the injected frequency was varied in small steps around the third harmonic of the electron gyrofrequency. Systematic variations with pump frequency were observed in the data obtained from all three diagnostics. Measurements of anomalous absorption, the downshifted maximum (DM) spectral feature, and heater-induced electron temperature enhancements all exhibited broad minima as the heater frequency approached the third harmonic of the electron gyrofrequency. In addition, the signal strength of the HF probe wave measured during heater off periods is also reduced at these and higher heater frequencies. The experimental findings suggest that at heater frequencies in the vicinity of the third gyroharmonic, small-scale field-aligned irregularities are not excited, whereas very small scale irregularities, of the order of a few electron cyclotron radii, which are responsible for the production of fast electrons, may be generated. The observed reduction in the diagnostic signal strength is then attributed to the ionized patches produced by these energetic electrons