The effect of medium properties on the energy loss suffered by a relativistic charged particle in a dielectric medium generating Cerenkov radiation is discussed. Here we have taken into account the effect of the coupling of the longitudinal (σ) mode with the transverse (λ) mode in the electromagnetic interaction. Calculation shows that the inclusion of λ-σ coupling in the transverse interaction affects significantly the radiation output. However the modification of the radiation due to the thermal state of the system becomes important at very high temperatures such as one finds in astrophysical situations. This temperature effect is negligible at ordinary temperatures and thus is undetectable in laboratory experiments.

A generalized Schrödinger formalism has been presented which is obtained as a Hilbert space representation of a Liouville equation generalized to include the action as a dynamical variable, in addition to the positions and the momenta. This formalism applied to a classical mechanical system had been shown to yield a similar set of Schrödinger like equations for the classical dynamical system of charged particles in a magnetic field. The novel quantum-like predictions for this classical mechanical system have been experimentally demonstrated and the results are presented.

The effect of velocity gradient across the magnetic field on the low frequency flute modes is examined in detail, using the normal mode analysis. It is shown that some new type of instabilities driven primarily by the velocitygradient arise and these excited modes eventually attain the convective saturation. The onset of plasma turbulence due to these instabilities may possibly be one of the major contributors for anomalous heating process and enhanced plasma resistivity.

A technique for improving the transmission of intense electron beams through cusp magnetic field in vacuum using dielectric drift tubes has been demonstrated. The plasma produced by the material of the dielectric tube increases the transmission efficiency by a factor of four over vacuum values.

Monte-Carlo calculations ind-s shell space have been done using two-body random interactions, to obtain ensemble-averagem-particle scalar moments up to fourth order. A shift of the spectrum shape from semi-circle to Gaussian with respect to the increase in number of particles can be clearly seen in terms of the ensemble-averaged fourth moment.

Using intermediate degreep-mode frequency data sets for solar cycle 22, we find that the frequency shifts and magnetic activity indicators show a “hysteresis” phenomenon. It is observed that the magnetic indices follow different paths for the ascending and descending phases of the solar cycle while for radiative indices, the separation between the paths are well within the error limits.

The charged particle orbits in electromagnetic fields on Kerr background as viewed from a locally non-rotating frame do not exhibit non-gyrating bound orbits, which was an essential feature in the earlier study of Prasanna and Vishveshwara, thus showing the non gyration to be due to the effect of dragging of inertial frames produced by the rotating black hole.

The effect of Gaunt factor correction on temperature estimation over a range 100 to 1500 eV had been studied. Greene’s analytical expression for the quantum mechanical Gaunt factor averaged over Maxwellian distribution is used. Transmission ratios are calculated with and without Gaunt factor for various combinations of beryllium foils, taking into account x-ray emission due to free-free transitions. A significant difference (≳ 15%) is observed between the temperatures estimated from classical and quantum mechanical curves, above 600 eV. Selection of foil combinations useful for estimating higher temperatures is also discussed.