Joint Colloquium Distinguished Lecture Series

Frequency and Polarization Transformer: A Switched Magnetoplasma Medium in a Cavity

photo of Dikshitulu Kalluri Wednesday, October 22, 2008
306 Soda Hall (HP Auditorium)
4:00 - 5:00 pm

Dikshitulu Kalluri
Professor
Electrical and Computer Engineering Department
University of Massachusetts Lowell

Downloadable PDF

Abstract:

When the medium surrounding a standing source wave in a cavity changes in time, interesting transformations happen: changes occur not only in amplitude and polarization of the wave, but also in its frequency. Such transformations are presented in detail in this talk.

This theoretical and simulation (using FDTD) research is performed in a one-dimensional cavity that consists of two rectangular perfect electric conductor (PEC) plates, separated by a small distance. Initially an elliptically polarized standing wave is present the cavity and the medium is free space. The medium in the cavity is then converted to a lossy magnetoplasma with an arbitrary space and time profile. Essentially this amounts to altering the medium in the cavity from a simple to a complex, dynamic (time-varying), dispersive (frequency dependent), anisotropic (direction dependent) and inhomogeneous (location dependent) medium. The case of longitudinal modes (the static magnetic field in the direction of the cavity dimension) is considered.

It is shown that the elliptically polarized source wave transforms into three circularly polarized waves, as a consequence of the medium change. It is further shown that each of the transformed waves has a unique frequency, amplitude and phase (with respect to the source wave).

The case of switching-off of the static magnetic field, when the source wave is a whistler wave, can lead to a wiggler magnetic field. By an appropriate choice of the parameters, millimeter-wavelength wigglers can be achieved. The case of switching-off the plasma can lead to an increase of frequency by orders of magnitude Plasma parameters for converting a 10 GHZ input signal to a 500 GHz output signal of significant amplitude will be discussed.

Some of the proof-of-the principle experiments on the effects of switching the medium, done by some groups, will be presented. Experimental challenges in obtaining a practical device of this kind will be opened for discussion.

Biography:

B. E. Andhra University, M.S. University of Wisconsin, D.I.I.Sc. Indian Institute of Science, Ph.D. University of Kansas

Expertise: Applied & Computational Electromagnetics Including Plasmas

Scholarly Interests: Electromagnetic wave interactions with complex media are the basis of many modern and emerging technologies in Optical, Plasma, Microwave, Geoelectromagnetic and Bioelectromagnetic Engineering. I have expertise and research interest in modeling, analyzing and computing time-varying, inhomogeneous, bianisotropic (chiral), dispersive, moving, periodic media. My recent research deals with frequency-shifting using magnetoplasmas and has applications in generating coherent tunable


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