Chandu Venugopal
Articles written in Pramana – Journal of Physics
Volume 21 Issue 1 July 1983 pp 1-10 Plasma Physics
Propagation of the electromagnetic ion-cyclotron wave in a fusion plasma
The propagation of the electromagnetic ion-cyclotron wave in a fusion plasma described by a loss-cone structure is discussed. The wavelength is assumed to be much larger than the ion Larmour radius and the ion plasma frequency ≫ the ion-cyclotron frequency. The two modes that propagate in the plasma interact strongly and fuse together under certain conditions making the plasma unstable. The coalescence of the modes is found to decrease with an increase in electron temperature.
Volume 28 Issue 2 February 1987 pp 181-193 Plasma Physics
Near perpendicular propagation of ion cyclotron modes in a deuterium-hydrogen-oxygen fusion plasma
A dispersion relation for the near perpendicular propagation of the electromagnetic ion cyclotron wave has been derived in a fusion plasma that has deuterium as a majority species, hydrogen as a minority species and fully ionized oxygen as an impurity constituent; all being modelled by loss cone distribution functions. The wave has a frequency
Volume 37 Issue 3 September 1991 pp 303-310 Research Articles
Stability of second harmonic minority heating in magnetic mirror systems
Chandu Venugopal P J Kurian G Renuka
A dispersion relation has been derived to study the stability of ion cyclotron (IC) propagation at the second harmonic of the minority component deuterium in a mirror confined plasma that has hydrogen as the majority species. We have worked in the frame of the majority ions; our dispersion relation can thus be used to study IC propagation in a single ion plasma also. Analysis of the dispersion relation yields two modes — one below and the other above the ion gyro-frequency ΘH of hydrogen. The expression for the growth rate is used to explicitly show that an instability can arise in the plasma when the loss-cone index
Volume 45 Issue 5 November 1995 pp 453-462
Ion cyclotron instabilities in a mildly relativistic hydrogen-deuterium fusion plasma
Chandu Venugopal P J Kurian G Renuka
A dispersion relation for the perpendicular propagation of the electromagnetic ion cyclotron wave around the second harmonic of the deuterium ion gyrofrequency in a mildly relativistic, anisotropic Maxwellian plasma with hydrogen as the majority species and deuterium as the minority component has been derived. The work has been carried out in the frame of reference of the majority hydrogen ions; to these ions the waves at 2ΘD would be at its own gyrofrequency.
Using a small quantity
In the next higher order, the dispersion relation is a quartic equation and is sensitively dependent on the relativistic factors. The plasma can now support four modes, both above and below the hydrogen gyrofrequency and consistent with the ordering scheme used. However the modes can now coalesce resulting in complex conjugate roots to the dispersion relation thereby indicating an instability.
The advantage of such a scheme is that two dispersion relations — one of which is independent of the relativistic factors and the other which is sensitively dependent on them can be separated out.
Volume 73 Issue 6 December 2009 pp 1111-1122
Stability of electrostatic ion cyclotron waves in a multi-ion plasma
M J Kurian S Jyothi S K Leju Molly Isaac Chandu Venugopal G Renuka
We have studied the stability of the electrostatic ion cyclotron wave in a plasma consisting of isotropic hydrogen ions ($H^{+}$) and temperature-anisotropic positively ($O^{+}$) and negatively ($O^{−}$) charged oxygen ions, with the electrons drifting parallel to the magnetic field. Analytical expressions have been derived for the frequency and growth/damping rate of ion cyclotron waves around the first harmonic of both hydrogen and oxygen ion gyrofrequencies. We find that the frequencies and growth/damping rates are dependent on the densities and temperatures of all species of ions. A detailed numerical study, for parameters relevant to comet Halley, shows that the growth rate is dependent on the magnitude of the frequency. The ion cyclotron waves are driven by the electron drift parallel to the magnetic field; the temperature anisotropy of the oxygen ions only slightly enhance the growth rates for small values of temperature anisotropies. A simple explanation, in terms of wave exponentiation times, is offered for the absence of electrostatic ion cyclotron waves in the multi-ion plasma of comet Halley.
Volume 96, 2022
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