Indian Journal of Radio & Space Physics

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(CODEN : IJRSAK        ISSN : 0367-8393)

VOLUME 37

NUMBER 1

FEBRUARY 2008

 

CONTENTS

 

Equatorial spread-F research in India: A brief review

7

        R Sekar* & D Chakrabarty

 

 

Cosmic ray anisotropies during the Oct. 28-31, 2003 Halloween event

28

        R P Kane*

 

 

Effect of dust particles on two-stream instability: A possible explanation for the persistence of ionization trails of Leonid meteor showers

34

V H Kulkarni* & P Muralikrishna

 

 

Influence of coronal mass ejections on global electric circuit

39

        C P Anil Kumar*, C Panneerselvam, K U Nair, K Jeeva, C Selvaraj, S Gurubaran & R Rajaram

 

 

Influence of IMF Bz on the variability of the minimum value of fo-F2

46

        M V Vijayakrishnan, C V Sreehari, Tiju Joseph Mathew & S R Prabhakaran Nayar*

 

 

Field solution within the ionospheric anisotropic plasma in presence of thunderstorm and lightning

51

        S S De*, S N Paul, M De, B K De & B Bandyopadhyay

 

 

Dielectric properties of some minerals of western Rajasthan

57

        R J Sengwa* & A Soni

 

 

Pressure and density of air in mines

64

        A Tan*, T X Zhang & S T Wu

 

 

 

*Authors for correspondence

 

 


Indian Journal of Radio & Space Physics

Vol. 37, February 2008, pp. 7-27

 

 

Equatorial spread-F research in India: A brief review*

 

R Sekar & D Chakrabarty

Physical Research Laboratory, Navrangpura, Ahmedabad 380 009, Gujarat, India

Received 23 October 2007; accepted 17 January 2008

The Equatorial Spread-F (ESF) is a complex phenomenon encompassing a wide range of scale sizes (covering more than six orders of magnitude) of irregularities in electron and ion densities as well as in electric fields. The generation mechanisms involve not only the plasma processes but also neutral processes. Thus, to understand the different facets of ESF manifestations, investigations have been carried out using multiple techniques. The research in this topic has practical implications as these irregularities affect the propagation of radio wave even in Ultra High Frequency band. Considerable amount of works have been done in India to understand this phenomenon. Some of the important results in the last three decades, as perceived by the authors, are reviewed in this paper. This involves results obtained from ground-based, rocket and satellite borne experiments conducted from India along with theoretical and laboratory simulations.

Keywords: Equatorial Spread-F, Plasma instabilities, Plasma bubble, Equatorial ionosphere

PACS No.: 94.20.-y, 94.20.Ww

 

  

 

Indian Journal of Radio & Space Physics

Vol. 37, February 2008, pp. 28-33

 

 

Cosmic ray anisotropies during the Oct. 28-31, 2003 Halloween event

R P Kane

Instituto Nacional de Pesquisas Espaciais – INPE, C. P. 515, 12245-970 - São José dos Campos, SP, Brasil

(e-mail: kane@dge.inpe.br)

Received 23 February 2006;revised  29 June 2007; accepted 1 January 2008

Using data from the Nagoya muon directional telescopes during the storm of 29 Oct. 2003, the anisotropies were traced at successive UT times. Some features were very prominent, positive in some directions, negative in others. In each, different directional telescopes indicated different magnitudes, implying large directional anisotropies. By tracing the anisotropies in space, one could conclude that the Earth was engulfed by the interplanetary blob and passed slightly in its northern part (same as North of Sun). These results are approximate, as the simple analysis was carried out assuming straight line paths for cosmic rays, while some bending in magnetic fields and some scattering may be involved. Nevertheless, useful information can be obtained even from one muon set up as shown here. Using more copious data from other sources would, of course, give more detailed information.

Keywords: Muon telescopes, Cosmic rays, Cosmic ray anisotropies; Geomagnetic storms

PACS No.: 95.85.Ry, 91.25.-r

 

 


Indian Journal of Radio & Space Physics

Vol. 37, February 2008, pp. 34-38

 

 

Effect of dust particles on two-stream instability: A possible explanation for the persistence of ionization trails of Leonid meteor showers

 

V H Kulkarni

10 Archen Co-Op Housing Society, Sector-4, Vashi, New-Bombay 400 703, India

and

P Muralikrishna

Divisão de Aeronomia, Instituto Nacional de Pesquisas Espaciais, INPE Av Dos Astronautas,
San Joáe dos Campos-SP 12245-470, Brazil

Received 9 November 2005; revised 26 March 2007; accepted 14 January 2008

Assuming a collisional plasma having dust particles and only electrons are magnetized, the two-stream instability is studied for the excitation of low frequency waves. The production and losses of both ions and electrons are included. In the absence of production, it is shown that losses by attachments of both ions and electrons on dust particles, two-stream instability require the drift velocity greater than ion acoustic velocity. The growth rate is reduced and the wave amplitude at saturation is reduced. Therefore the generation and magnitudes of ionization density irregularities is reduced. It is expected that the cross-field diffusion of ionization due to wave turbulence is affected. It is known that during meteor shower periods the E-region of the ionosphere has a significant number of dust particles. Therefore density irregularities in the ionosphere are modified. Also amplitude dependent diffusion rate is reduced. It is suggested that the presence of dust particles may be a reason for persistence of ionization trails seen for longer periods during Leonid meteor showers

Keywords: Ionization trails, Leonid meteor showers, Meteor showers, Collisional plasma,

PACS No: 52.35 Dm, Fp; 94.10 Nh, 94.20 Db, Gg, Rr

 

 

 

 

 

Indian Journal of Radio & Space Physics

Vol. 37, February 2008, pp. 39-45

 

 

Influence of coronal mass ejections on global electric circuit

C P Anil Kumar*, C Panneerselvam, K U Nair, K Jeeva, C Selvaraj, S Gurubaran & R Rajaram1

Equatorial Geophysical Research Laboratory, Indian Institute of Geomagnetism, Krishnapuram, Tirunelveli,
Tamilnadu 627 011, India

1Indian Institute of Geomagnetism, New Panvel (W), Navi Mumbai, 410 218, India

cpanil@iigs.iigm.res.in

Received 20 June 2006; revised 31 May 2007; accepted 29 January 2008

This paper is concerned with the elucidation of flow of particles and field from the sun into the terrestrial system and their subsequent role in Global Electric Circuit (GEC). Many flare associated Coronal Mass Ejections (CMEs) have been studied from ACE satellite data during the last phase of the 23rd solar cycle. Such solar ejections consist of hot electrons, protons and helium ions embedded in magnetic fields of various intensities and which travel with velocities greater than supersonic speed towards the earth and breach terrestrial magnetic fields (under favourable conditions) and cause geomagnetic storms. Contemporary data of geoelectrical measurements made at the high latitude Indian Antarctic Research Station, Maitri (70.45°S, 11.44°E) have also been used to investigate the electrical processes during, before and after the above events. The study leads to the conclusion that CMEs enhance the population of the multi-ion plasma species, which paves the way for an increase in the overhead ionospheric electric potential during the onset or even up to the main phase of the magnetic disturbance. The near earth electrical environment is besieged with magnetic disturbance at the high latitude.

Keywords: Coronal mass ejections, Atmospheric electricity, Global electric circuit

PACS No.: 96.60 ph, 92.60 Pw


Indian Journal of Radio & Space Physics

Vol. 37, February 2008, pp. 46-50

 

 

Influence of IMF Bz on the variability of the minimum value of fo-F2

M V Vijayakrishnan, C V Sreehari, Tiju Joseph Mathew & S R Prabhakaran Nayar

Department of Physics, University of Kerala, Kariavattom, Thiruvananthapuram 695 581, Kerala, India

E-mail: srp@md2.vsnl.net.in

Received 7 August 2006; revised 10 July 2007; accepted 15 January 2008

The critical frequency of the ionosphere, apart from the diurnal and annual variations exhibit day-to-day variations. The minimum value of fo-F2 around the pre-sunrise period also has a day-to-day change. In this work, the relation between the magnitude of fo-F2 minimum and h′F2 values around the pre-sunrise period and their relation with the sign of the north-south component of the interplanetary magnetic field (IMF) is investigated. The minimum value of fo-F2 for each day is found to be related to the IMF north-south component, with the fo-F2 value tending to be larger when the IMF is northward and smaller when the IMF is southward. The northward IMF Bz is seen to produce an eastward electric field at the ionosphere and move the ionospheric plasma to higher altitudes resulting in higher critical frequencies. Whereas a southward IMF Bz produce a westward electric field and move the ionospheric plasma to lower altitudes resulting in lower critical frequencies.

Keywords: Interplanetary magnetic field (IMF), IMF Polarity, Critical frequency, Ionospheric critical frequency

PACS No.: 96.35.Pb

 

 

Indian Journal of Radio & Space Physics

Vol. 37, February 2008, pp. 51-56

 

 

Field solution within the ionospheric anisotropic plasma in presence of thunderstorm and lightning

S S De1, S N Paul1, M De1, B K De2 & B Bandyopadhyay1

1Centre of Advanced Study in Radio Physics and Electronics, University of Calcutta, Kolkata 700 009, India

2Department of Physics, Tripura University, Tripura 799 130, India

Received 9 June 2006; revised 16 July 2007; accepted 17 September 2007

In the presence of thunderstorm and lightning, Maxwell’s equations for the ionospheric anisotropic plasma have been solved, considering the influence of geomagnetic field and time-varying random irregularities developing an ac magnetic field. This analysis has been used to study the electrodynamics of middle atmosphere during thunderstorm and lightening. The variations of thundercloud and lightning induced electric field have been numerically estimated for some specific ionospheric height range. The fluctuation of electron number density within the medium is also studied.

Keywords: Ionospheric plasma, Lightning discharges, Anisotropic plasma

PACS No.: 92.60.PW, 92.60. Ta

 


Indian Journal of Radio & Space Physics

Vol 37, February 2008, pp  57-63

 

 

Dielectric properties of some minerals of western Rajasthan

R J Sengwa*,1 & A Soni2

1Dielectric Research Laboratory, Department of Physics, J N V University, Jodhpur 342 005, Rajasthan, India

2Well Logging Services, Oil and Natural Gas Corporation Limited, Rajahmundry 533 106 (AP), India

*Email: rjsengwa@rediffmail.com

 Received 10 May 2006; revised 9 July 2007; accepted 10 October 2007

Dielectric constant e¢ and loss e¢¢ of dry samples of clay, siliceous earth, fuller’s earth, gypsum, lignite, calcite, tourmaline and magnesium rock of opencast mines of western Rajasthan, India, were studied in the frequency range 100 Hz - 100 kHz and also at X-band microwave frequencies. It is observed that the values of e¢ decreases with increase in frequency in low frequency region. Exceedingly high e¢ values were found for clay, siliceous earth and, fuller’s earth at lower frequencies in the 100 Hz to 100 kHz frequency range. The complex plane plots (e¢¢ versus e¢) of these minerals are the Cole-Cole arcs. The low frequency limiting dielectric constant eo, high frequency limiting dielectric constant e¥, relaxation time of dipole rotation t and, distribution parameter a of these materials were determined using the Cole-Cole plots. All these minerals have large value of a, and their t values varies in the range from » 0.1 to 11 ms. Frequency dependent ac conductivity of these minerals has been determined and discussed and, the contribution of sample bulk density and percent weight of the constituents of their chemical composition on the microwave values of e¢ and e¢¢ has been explored for the studied samples.

Keywords: Minerals, Dielectric constant, Dielectric dispersion, Conductivity

PACS No.: 78.20.Ci, 84.40.Xb, 91.60.Pn

 

Indian Journal of Radio & Space Physics

Vol. 37, February 2008, pp. 64-67

 

 

Pressure and density of air in mines

 

A Tan & T X Zhang

Department of Physics, Alabama A & M University, Normal, Alabama 35762, USA

S T Wu

Center for Space Plasma and Aeronomic Research, The University of Alabama in Huntsville, Huntsville
Alabama 35899, USA

Received 14 August 2006; revised 9 July 2007; accepted 16 January 2008

Mines are the deepest cavities in the Earth’s crust, where man has set foot and worked. The observed temperature gradients within the mines range from 10 to 50 K/km. In this paper, the pressure and density of air inside mines are calculated by integrating the governing equation for the number density obtained from the hydrostatic equation and the perfect gas laws. The variation of the acceleration of gravity with depth is seen to have only minimal effects on the pressure and air density. The higher temperature gradients inside the mines are found to depress both the pressure and density of air there. Whereas the pressure must necessarily increase with depth due to the hydrostatic equation, the density of air can increase, remain constant, or actually decrease with depth, for temperature gradients of less than, equal to, or greater than 34 K/km, respectively. Air conditions in the deepest mine in the world are discussed.

Keywords: Air pressure, Air density, Mines, Mine air

PACS No.: 94.10.Dy, 94.10.Fa, 93.30.Bz