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Biography

Dr. Poornima Varma is a Women Scientist, Department of Physics at Dr. H. S. Gour Central University, Sagar, M. P., India. She finished her PhD in 1992 from the same university. Academic experienced: J.R.F. [MAPCOST]: 1988 – 1991; R.A. [CSIR] : 1993 – 1998; S.R.A. [ISRO] : 2003 – 2005; Women Scientist [DST] : April, 2005 – March, 2008; Women Scientist [DST] : May, 2008 – April, 2011; Women Scientist [DST] : March, 2012 – Continue… Dr. Poornima designed following courses at University Syllabus: 1. Ph.D. Course Syllabus “Advance Plasma Physics” 2. M.Sc. IV Semester Plasma Physics. 3. An elective paper of “Atmospheric Physics” for outside student of IIIrd Semester. Successfully run in the department. Research Interest: Theoretical Modulation of Plasma Approach in Space Physics; Magnetosphere-Ionosphere Coupling; Auroral Electrodynamics; Earth’s Magnetosphere; Gas discharge physics; Theoretical Approaches; Atmospheric Physics; Low frequency waves

Abstract

The space plasma constitutes a natural laboratory for the study of various plasma phenomena useful for the laboratory plasma devices also. The research in space plasma physics has a long history in India since the work of Saha on interstellar plasma in late twenties. The early twenty one centuries saw the emerging of the groups in National laboratories engaged in research in theoretical and experimental aspects. Rocket and satellites observations have revealed the enthuastics features in space physics. The currents in the auroral ionosphere are the part of a large three-dimensional current system, coupling the ionosphere to magnetosphere. One of the main problem in auroral plasma physics concerns the acceleration of the electrons to kinetic energies much higher than their initial thermal energies. Both theory and observations from both the current regions downward (Marklund et al., 2001) and upward (McFadden et al., 1999) have indicated that the electrons are accelerated by parallel electric fields. The precipitating electrons cause the aurora and carry the field-aligned currents in the upward current regions. Low frequency waves (Alfven waves, Kinetic Alfven waves, Electromagnetic Ion-cyclotron waves, Electrostatic Ion-cyclotron waves) are investigated. The investigation is based upon particle aspect approach as well as kinetic approach which we have been pursuing since last 25 years (e.g. Varma, et al.., 2007 and references therein; Ruchi Mishra and M.S.Tiwari, 2007 and references therein; Ahirwar, et al.., 2006, 2007 and references therein; Shukla, et al.., 2007 and references therein, Agarwal et al, 2011 and reference therein, Patel et al 2012 and references therein] in various space regions. The study is explaining the broad scenario of space around earth magnetosphere. The utility of the work is justified by many satellite observations. The applicability of this model is assumed for auroral acceleration region, plasma sheet boundary layer and cusp region. There are enough observational data to support the hypothesis that small scale, discrete auroral arcs optically observed from the ground measured directly by satellites and rockets in the altitudes range from 900 km to 2 RE above the auroral ionosphere are closely connected phenomena (Streltov, et al.1999). Direct measurements from satellites (Karlsson, et al., 1996) and rockets (Boehm et al., 1990) have shown that the discrete fluxes of K eV electron registered at the auroral zone are often correlated with small scale localized electromagnetic disturbances and interpreted as KAWs. The outcome of the investigation is anticipated to explain the complexity and diversity of Magnetosphere-ionosphere coupling and auroral electrodynamics by studying the wave phenomena of VLF waves at the substorm times which may be useful to study space environment at higher latitudes useful for polar satellites. This study may play a major role to unfold the mystery of substorm behavior effective on earths. This study also may be utilized to explain wave phenomena and accelerations of solar atmosphere [Ahirwar et al., 2007] and for thermonuclear plasmas which are the future energy programs of the next era. Recently, observations from the Polar and Cluster satellites have indicated that large-amplitude kinetic Alfven waves are observed throughout the plasma sheet, particularly at the PSBL during substroms (Keiling et al..,2003). Electrostatic ioncyclotron instabilities observed in the auroral acceleration region by various satellites like S3-3, ISEE-1, Viking and recently by Polar, Freja and FAST satellites (Mozer et al., 1997; Hamrin, et al., 2001), has been of considerable interest to plasma physicists as the instability appear in almost all types of magnetized plasma and under a variety of Physical conditions ranging from fusion and laboratory experiments to space plasma. The behavior of low frequency waves are studied in view of Birkeland current system, magnetospheric morphology and auroral acceleration pattern. Field-aligned current, development of parallel and perpendicular electric fields, perpendicular ion heating, wave excitation are examined in terms of LF waves. The Alfven waves are an integral part of the substorms, have become clear since their prediction (Keiling et al.., 2000). Observational evidence of EMIC waves in auroral acceleration region are presented from the FAST satellites (Chaston et al., 2002) and large parallel electric fields measured by the Duo Deca Electron Ion Spectrometer (DDEIS) component of HYDRA instruments on board Polar satellites (Hull et al., 2003). The electrostatic ion-cyclotron instability is the fundamental instability exhibited by current carrying magnetized plasma. It has a smaller threshold drift velocity than most other current driven instabilities (Kindel and Kennel, 1971). It has been observed in the auroral acceleration region at a broad range of altitudes by the S3-3 satellites, Freja and FAST satellites in association with the parallel electric field, ion and electron beams (Gavrishchaka et al., 2000). The EIC waves play a key role in transverse acceleration of ions, generating anomalous resistivity and in explaining many other effects. The study of low frequency waves phenomena are of global interest. The various international organizations are involved to investigate the same pattern of the instabilities concerning the electromagnetic emissions, plasma transport, micro pulsations and heating of the thermonuclear plasma by low frequency waves. Various sets of magnetometer system in different countries are installed to observe the magnetic field variations at the quiet time and sub storm times.