Nagendra Singh

Resonances cone and interference pattern in the field of a point charge in a flowing warm magnetoplasma

The group velocity resonance cone in a drifting warm magnetoplasma is studied. Potential of a point charge is calculated in such a plasma. It is found that for a drift velocity Vd<Vt/tan ϑc, where Vt is the electron thermal velocity and ϑc is the cold cone angle, the downstream interference structure is useful for diagnostics of electron temperature using the formulae of a stationary plasma. The downstream interference pattern is appreciably modified for Vd≳Vt/tan ϑc. The upstream interference pattern is appreciably modified even for small drifts. For Vd≳Vt/tan ϑc, a new interference pattern appears for angles given by ϑc<ϑ<180°−ϑc. This new interference pattern is useful from the view point of measuring field‐aligned drifts in laboratory and space plasmas.

Interference structure near the resonance cone

By comparing theoretical and experimental results, the Airy function‐like behavior of the interference structure near the resonance cone has been confirmed. This leads to a rigorous method for determining the resonance cone angle.

Fields of an electric dipole perpendicular to a magnetostatic field in a hot plasma

The radiation fields of an electric dipole oriented perpendicular to the magnetostatic field in a hot uniaxial plasma are considered. The behavior of the fields near the resonance cone for the perpendicular and parallel orientations are found to be similar. A procedure is shown for estimating the electron temperature and density by measurements on the characteristic angular distribution of the fields near the resonance cone.

Effect of a sheath on the fields of a probe in a hot magnetized plasma

A probe excites two waves, a slow and a fast wave in a hot magnetized plasma when ω<ωp and ωc≫ωp. These waves propagate only within a cone of half‐cone angle sin−1(ω/ωp). It is found that the sheath around the probe effectively attenuates the two waves and the slow wave is attenuated more than the fast one.

Radiation resistance of a dipole in a drifting magnetoplasma

The radiation resistance R of a short electric dipole in a drifting magnetoplasma has been calculated. For very small length, R is found to behave as V_{0}^{-3} where V_{0} is the drift velocity along the magnetostatic field.

Fields of short radio‐frequency probes in a magnetized plasma

The diagnostics of a magnetized plasma can be done by measuring the spacings of the interference structure in the angular distribution of the field of a properly excited probe in the plasma. In this paper the effect of probe dimensions on the interference structure is investigated. The sheath around the probe is found to have profound effects on the angular distribution of both the phase and the amplitude of the filed of the probe. This investigation reveals that only thin electric dipole of half‐length less than 30 Debye lengths or so is useful for the plasma diagnostics.

Phase and group velocity in a drifting magnetoplasma

Relationship between group and phase velocities of electromagnetic waves in a drifting uniaxial plasma is discussed. When determining whether propagation between two points is possible, the allowed direction of the group velocity vector and not that of the phase velocity vector is important.

Angular phase distribution of the field of an electric dipole in a hot magnetoplasma

The angular distribution of the phase of the fields of an electric dipole with and without a sheath in a hot magnetoplasma is calculated. Like the amplitude distribution of the field, the phase distribution can also be used for estimating the electron temperature.

SCORM in Brihaspati-3 learning management system

In order to make content independent of LMS where it is deployed standards have been defined. These facilitate shareability, reusability, and interoperability of learning content. Many standards have evolved in last many for this purpose. SCORM (Sharable Content Object reference Model) standard proposed by Advanced Distributed Learning (ADL) is the most popular and commonly used one. In this paper, we are explaining SCORM architecture and use of the SCORM package creator in Brihaspati-3 LMS.

An S-band printed dipole with its feed line

Some experimental results on an S-band printed dipole are reported. The printed dipoles are fed by a strip line. The transition between the strip line and a coaxial line is investigated in detail. It is found that a specific transition gives the least VSWR in the coaxial line.