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Browsing by Author "Krishan, V"

Browsing by Author "Krishan, V"

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  • Polarization Changes of Radiation through Stimulated Raman Scattering 
    Gangadhara, R. T; Krishan, V (The American Astronomical Society, 1993-10)
    We study change in the polarization of electromagnetic waves due to the stimulated Raman scattering in a plasma. In this process an electromagnetic wave undergoes coherent scattering off an electron plasma wave. It is found ...
  • Possible effects of positronium negative ion on 0.511 MeV gamma-ray line in astrophysical sources 
    Sivaram, C; Krishan, V (Springer, 1982-07)
    The astrophysical importance of the negative positronium ion, detected recently in the laboratory, has been pointed out. It is found that the presence of Ps(-) ions will contribute additionally to the width of the 0.511 ...
  • Power spectra of the fluctuations in the solar wind 
    Krishan, V (Springer Netherlands, 2008)
    The power spectra of the velocity, the magnetic field and the density fluctuations and their inter-relationships are investigated in the turbulent solar wind using the dimensional approach of the Kolmogorovic type. While ...
  • Pressure structure of solar coronal loops. III 
    Sreedharan, T. D; Sasidharan, K; Satya Narayanan, A; Krishan, V (Springer Netherlands, 1992-12)
    The theory of ideal magnetohydrodynamic turbulence in cylindrical geometry is used to study the steady-state structure of a coronal loop. The pressure profile is derived from MHD equations by representing the velocity and ...
  • A probable initial configuration of a flaring loop 
    Krishan, V (Institute of Physics, 1986-02)
    A clue to the preflare configuration of a magnetic loop is obtained based on Taylor's hypothesis that the decay of energy to a minimum with magnetic helicity remaining constant leads to a force free state. The numerical ...
  • Probing Dust in the Atmosphere of Brown Dwarfs through Polarization 
    Sengupta, S; Krishan, V (The American Astronomical Society, 2001-11)
    The theoretical analysis and observational evidence indicate that a brown dwarf with an effective temperature greater than 1300 K would have a dust cloud in its atmosphere. In this Letter, we show that dust scattering ...
  • Production of the active galactic nuclei continuum via coherent plasma processes 
    Krishan, V (Cambridge University Press, 1988)
    It appears possible to explain both the typical continuum electromagnetic spectrum and the relativistic velocities of electrons in the region of an active galactic nucleus (AGN) around a supermassive black hole (SMBH) by ...
  • Propagation effects on polarization of pulsar radio emission 
    Gangadhara, R. T; Lesch, H; Krishan, V (The Royal Astronomical Society, 1999-08)
    We consider the role of a propagation effect such as stimulated Raman scattering on the polarization of radio pulses. When an intense electromagnetic wave with frequency close to the plasma frequency interacts with the ...
  • Pulsating radio emission at decametre wavelengths from the sun 
    Sastry, Ch. V; Krishan, V; Subramanian, K. R (Indian Academy of Sciences, 1981-03)
    Observations on the pulsation pattern in the time profile of short duration solar radio bursts at decametre wavelengths are presented. The pulsations are found to be present predominantly in the saturation phase of the ...
  • Radiation from an electron beam-magnetoplasma 
    Krishan, V (Institute of Physics, 1980-08)
    The possibility of direct generation of electromagnetic radiation at and near electron plasma frequency from an electron beam-magnetoplasma system is explored. The role of the electron beam is replaced by the electron ...
  • Radio emission by parallel acceleration mechanism 
    Krishan, V; Sivaram, C (Springer, 1983-04)
    The equations describing the linear-acceleration mechanism of radiation emission are generalized and applied to type III and IIIb solar radio bursts. A general expression for the power emitted by an electron in a spatially ...
  • Radio emission from a helical electron beam-plasma system in a twisted magnetic field 
    Krishan, V (Institute of Physics, 1982-01)
    The excitation of electromagnetic radiation near the harmonics of electron plasma frequency from a helical electron beam travelling parallel to a helical magnetic field through a stationary inhomogeneous plasma is studied. ...
  • Radio emission from an intense electromagnetic beam-plasma system 
    Krishan, V (D. Reidel Publishing Co., 1979-06)
    Interaction of a high-intensity and low-frequency electromagnetic beam with a plasma is investigated. The dynamics of plasma particles under this strong electromagnetic field is calculated without using the perturbation ...
  • Radio frequency emission in electron beam-plasma and beam-beam interaction 
    Krishan, V; Sinha, K. P; Krishan, S (D.Reidel Publishing Co.,, 1978-01)
    A linear excitation of electromagnetic modes at frequencies ~_ (n+1/2)ωce , in a plasma through which two electron beams are contra-streaming along the magnetic field is investigated. This may be a source of the observed ...
  • Radio wave heating of astrophysical plasmas 
    Gangadhara, R. T; Krishan, V (Indian Academy of Sciences, 1990-12)
    The coherent plasma process, parametric decay instability (PDI), has been applied to a homogeneous and unmagnetized plasma. These instabilities cause anomalous absorption of strong electromagnetic radiation under specific ...
  • Raman scattering of the synchrotron self-absorbed radiation in accretion discs 
    Krishan, V (Royal Astronomical Society, 1988-01)
    The quasar non-thermal continuum in the radio region can undergo Raman scattering in the accretion disc plasma around the central black hole provided that the frequency and the wave vector matching and the threshold ...
  • Rapid polarization variability in intense sources 
    Gangadhara, R. T; Krishan, V (The American Astronomical Society, 1995-02)
    We have recently reported the polarization changes of the intense electromagnetic radiation, in active galactic nuclei and pulsars, due to stimulated Raman scattering. In this paper, we show that the incident and the ...
  • Reflection of radio radiation at ionization fronts in emission line regions and accretion disks of active galactic nuclei 
    Krishan, V (The Royal Swedish Academy of Sciences, 1994)
    It is known that high frequency short duration electromagnetic pulses can be generated by reflection of low frequency radiation off relativistically moving ionization fronts. In addition, a part of the incident electromagnetic ...
  • Relationship between horizontal flow velocity and cell lifetime for supergranulation from SOHO Dopplergrams 
    Paniveni, U; Krishan, V; Singh, J; Srikanth, R (Royal Astronomical Society, 2004-02-01)
    A study of 50 supergranular cells obtained from Solar and Heliospheric Observatory (SOHO) Dopplergrams was undertaken in order to investigate the relationship between the lifetime (T) and the horizontal flow velocity (vh) ...
  • Relationship between horizontal flow velocity and cell size for supergranulation using SOHO Dopplergrams 
    Krishan, V; Paniveni, U; Singh, J; Srikanth, R (Royal Astronomical Society, 2002-07)
    A study of 90 supergranular cells obtained from SOHO Dopplergrams was undertaken in order to investigate a possible relation between the sizes and peak horizontal velocities of the cells. For the sample obtained, the two ...

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