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Your search keyword '"Ganguli, Gurudas"' showing total 112 results
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112 results on '"Ganguli, Gurudas"'

102. Generation of “spiky” potential structures associated with multiharmonic electrostatic ion-cyclotron waves.

Author

Su-Hyun Kim, Merlino, Robert L., and Ganguli, Gurudas I.

Subjects
CYCLOTRON waves, ELECTROMAGNETIC waves, ELECTROSTATICS, ELECTRIC fields, ION flow dynamics, ELECTRODYNAMICS
Abstract

The production of coherent, “spiky” electrostatic potential structures, similar to the spiky electric-field structures that have been observed in the Earth’s auroral region, is investigated in a magnetized Q machine plasma. These structures are associated with coherent multiharmonic electrostatic ion-cyclotron (EIC) waves in a current-free plasma having a localized region of ion flow shear (ion flow parallel to B with a gradient in the direction transverse to B). A multiharmonic EIC spectrum is detected in the region of ion flow shear when broadband electrostatic white noise is applied to the plasma column from an antenna. The time series of the potential fluctuations exhibit spiky structures with repetition rates near the ion-cyclotron frequency. Spiky structures can arise from linear combinations of phase-locked multiharmonic EIC waves when the amplitudes of the harmonic components are comparable to that of the fundamental EIC mode. [ABSTRACT FROM AUTHOR]

Published
2006
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103. Amplification of electrostatic ion-cyclotron waves in a plasma with magnetic-field-aligned ion flow shear and no electron current.

Author

Su-hyun Kim, Agrimson, Erick, Miller, Michael J., D'angelo, Nicola, Merlino, Robert L., and Ganguli, Gurudas I.

Subjects
PLASMA gases, CYCLOTRONS, PLASMA waves, ELECTROMAGNETIC waves, ANTENNAS (Electronics), MAGNETIC fields
Abstract

Experimental demonstration of the amplification of electrostatic ion-cyclotron waves in a plasma with parallel ion flow shear but no magnetic-field-aligned electron current is presented. Waves with frequencies near the ion gyrofrequency and multiple harmonics launched from an antenna are observed to grow in amplitude in a region of ion flow shear. Amplification of multiple cyclotron harmonics was observed when a broadband (white noise) signal was applied to the launching antenna. Implications of these results for plasma wave excitation in the Earth’s auroral region are discussed. [ABSTRACT FROM AUTHOR]

Published
2004
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105. Investigation of a Streaming Instability Due to Dust-Charge Fluctuations.

Author

Gyoo-Soo Chae, Scales, Wayne A., Ganguli, Gurudas, Bernhardt, Paul A., and Lampe, Martin

Subjects
DUSTY plasmas, ELECTRIC properties of dust, PLASMA waves, PLASMA instabilities
Abstract

Presents a numerical simulation model to study the effect of dust charging on waves and instabilities in unmagnetized dusty plasmas. Main features of the model; Investigation of ion acoustic streaming instability; Ion density perturbations and dust-charge fluctuations.

Published
2001
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106. Collisional and Nonlinear Effects on Grain Charge and Intergrain Force.

Author

Lampe, Martin, Ganguli, Gurudas, Gavrishchaka, Valeriy, Goswami, Rajiv, and Joyce, Glenn

Subjects
*COLLISIONS (Nuclear physics), *ION traps, *DUSTY plasmas
Abstract

In recent work we have shown that trapped ions, created by occasional collisions, typically dominate the plasma response to a stationary dust grain in non-flowing plasma. A procedure is outlined for calculating the ion current to the grain, including trapped ions, and it is shown that the trapped ion current is typically larger than the OML ion current. The electrostatic interaction between two grains is also discussed. This problem is solved in context of OML theory, with no trapped ions included. The result is that the interaction is purely repulsive, and nonlinear terms due to the presence of two grains increase the repulsion as compared to the one-grain potential. The twograin problem has not yet been solved with trapped ions, but the possibility of attractive electrostatic forces is discussed. [ABSTRACT FROM AUTHOR]

Published
2002

107. Geophysical Plasmas and Atmospheric Modeling.

Author

SCIENCE APPLICATIONS INTERNATIONAL CORP MCLEAN VA, Hyman, Ellis, Drake, James, Ganguli, Gurudas, Ganguli, Supriya, Goodrich, Charles, SCIENCE APPLICATIONS INTERNATIONAL CORP MCLEAN VA, Hyman, Ellis, Drake, James, Ganguli, Gurudas, Ganguli, Supriya, and Goodrich, Charles

Abstract

Contents: Magnetospheric Physics: High Frequency Waves; Whistler Growth in a Cold Plasma Injection Experiment; Collective Particle Accelerator Studies; Magnetosphere-Ionosphere Coupling; High Latitude Ionospheric Investigations; Plasma Transport in the Auroral Return Current Region; Ion Cyclotron Wave Turbulence in the Auroral Ionosphere; Preferred Scale Size in the Structuring of Barium Clouds; Spectral Characteristics of Interchange Turbulence in the Ionosphere; Debris Air Coupling in HANE and int he NRL Laser Experiment; Power Spectral Density of Radiating Plasma Clouds; Debris charge States in HANE and in the NRL Laser Experiment; Lwo Frequency Instabilities in HANE; Numerical Studies of the Dynamics of the Summer Monsoon; Middle Atmosphere Transport and Chemistry Studies.

Published
1986

108. Geophysical Plasmas and Atmospheric Modeling.

Author

SCIENCE APPLICATIONS INC MCLEAN VA, Hyman,Ellis, Chaturvedi,Pradeep, Chen,James, Drake,Jim, Ganguli,Gurudas, SCIENCE APPLICATIONS INC MCLEAN VA, Hyman,Ellis, Chaturvedi,Pradeep, Chen,James, Drake,Jim, and Ganguli,Gurudas

Abstract

In the following subsections we will describe the major accomplishments in each of the following research efforts: (A) magnetospheric computer simulation, (B) non-linear saturation and transport via the lower hybrid drift instability, (C) the current driven ion cyclotron instability, (D) tearing-mode stability properties of an anisotropic plasma layer, (E) analyses of high latitude irregularity phenomena, (F) auroral plasma transport, (G) the EXB instability, (H) the morphology of a multi-bubble system in the ionosphere, (I) double layer simulations, (J) anomalous resistivity of auroral electrons, (K) energy exchange in the Io plasma torus, (L) uranium cloud modeling, (M) NRL Laser/HANE experiment support, (N) fractal theory applied to striating ionospheric plasma clouds, (O) elf/vlf wave generation, (P) ozone transport in the lower atmosphere and, (Q) stratospheric dynamics.

Published
1983

112. Dynamics in a multicomponent plasma near the low-frequency cutoff.

Author

Ganguli G and Rudakov L

Abstract

The distinctive feature of a multicomponent plasma is found to be a first order rotation of the light ion fluid with a characteristic frequency, Omega(r). A resonance at omega=Omega(r) results in plasma oscillation with unique properties. Coupling of the fast rotation time scale with the slow magnetosonic time scale leads to a nonlinear Schro dinger equation for the system and suggests the possibility of strong structural turbulence at MHD scales.

Published
2004
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