scholarly journals Application of ionospheric tomography for high frequency oblique incidence ray tracing

2016 ◽  
Vol 58 (6) ◽  
Author(s):  
Sandip Nandi ◽  
Bijoy Bandyopadhyay

<p>Recognizing the applicability of tomographic imaging in the ionosphere, the reconstruction method has been applied to generate more realistic low latitude ionospheric background based on the Ionex TEC data and also direct measurement TEC data over West Bengal, India. Using these backgrounds, ray tracing of high frequency waves has been performed. Influence of Earth’s magnetic field and also the existence of horizontal gradient of electron concentration in the ionosphere are considered separately for analyzing the ray tracing algorithm. Evaluation of ray tracing parameters and maximum usable frequency for different ground range ensures the possibility of application of ionospheric tomography technique for accurate ray tracing. The analysis shows accurate ray tracing for HF waves, thus defeating the restriction of choice of ionospheric model for analytical ray tracing methods. Performance analysis of the ray tracing technique presented in this paper ensures the consistency of speed with the other methods.</p>


2018 ◽  
Vol 27 (12) ◽  
pp. 1850114 ◽  
Author(s):  
Yang Huang ◽  
Yi-Ping Dong ◽  
Dao-Jun Liu

We study the photon’s motion around a black hole in the presence of a plasma whose density is a function of the radius coordinate by a renewed ray-tracing algorithm and investigate the influence of the plasma on the shadow of the black hole. The presence of plasma affects not only the size but also the shape of the black hole shadow. Furthermore, the influence of plasma on trajectories of photons depends on the frequency of the photons. For the high-frequency photons, the influence is negligible, on the contrary, the trajectories of low-frequency photons are affected significantly by the plasma. Interestingly, it is also found that the black hole image would take on a multi-ring structure due to the presence of plasma.





Author(s):  
Wang Jun-Feng ◽  
Ding Gang-Yi ◽  
Wang Yi-Ou ◽  
Li Yu-Gang ◽  
Zhang Fu-Quan


Author(s):  
R.L. Ebeling ◽  
J. Hiatt ◽  
O. Adetokunbo ◽  
M. Goldman ◽  
B. Curran ◽  
...  




2014 ◽  
Author(s):  
Guojin Feng ◽  
Ping Li ◽  
Yingwei He ◽  
Yu Wang ◽  
Houping Wu


1988 ◽  
Vol 37 (3) ◽  
pp. 469-474 ◽  
Author(s):  
A Bahnsen ◽  
M Jespersen ◽  
E Ungstrup ◽  
R Pottelette ◽  
M Malingre ◽  
...  


2016 ◽  
Vol 81 (724) ◽  
pp. 563-572 ◽  
Author(s):  
Momoko YOSHIMURA ◽  
Shinichi KASAHARA


1968 ◽  
Vol 46 (10) ◽  
pp. S638-S641 ◽  
Author(s):  
D. B. Melrose

The acceleration of ions from thermal velocities is analyzed to determine conditions under which heavy ions can be preferentially accelerated. Two accelerating mechanisms involving high-and low-frequency hydromagnetic waves respectively are considered. Preferential acceleration of heavy ions occurs for high-frequency waves if the frequency spectrum falls off faster than (frequency)−1. For the low-frequency waves heavy ions are less effectively accelerated than lighter ions. However, very heavy ions can be preferentially accelerated, the abundances of the very heavy ions being enhanced by a factor Ai over the thermal abundances. Acceleration of ions in the envelope of the Crab nebula is considered as an example.



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