Cyclotron resonance gain in the presence of collisions
Cyclotron resonance gain in the presence of collisions
Files
Publication or External Link
Date
2017
Authors
Cole, Nightvid
Advisor
Antonsen, Thomas M
Ott, Edward
Ott, Edward
Citation
DRUM DOI
Abstract
The conditions needed for the amplication of radiation by an ensemble of
magnetized, relativistic electrons that are collisionally slowing down are investigated.
The current study is aimed at extending the work of other researchers in developing
solid-state sources of Terahertz radiation. The source type considered here is based
on gyrotron-like dynamics of graphene electrons, or it can alternately be viewed
as a solid state laser source that uses Landau levels as its band structure and is
thus similar to a quantum cascade laser. Such sources are appealing because they
oer the potential for a compact, tunable source of Terahertz radiation that could
have commercial applications in scanning, communication, or energy transfer. An
exploration is undertaken, using linear and nonlinear theories, of the conditions
under which such sources might be viable, assuming realistic parameters. Classical
physics is used, and the model involves electrons in monolayer graphene assumed to
be pumped by a laser, follow classical laws of motion with the dissipation represented
by a damping force term, and lose energy to the electromagnetic eld as well. The
graphene is assumed to be in a homogeneous magnetic eld, and is sandwiched
between two partially-transmissive mirrors so that the device acts as an oscillator.
This thesis incorporates the results of two approaches to the study of the
problem. In the rst approach, a linear model is derived semi-analytically, which is
relevant to the conditions under which there is gain in the device and thus stable
operation is possible, versus the regime in which there is no net gain. In the second
approach, a numerical simulation is employed to explore the nonlinear regime and
saturation behavior of the oscillator. The simulation and the linear model both
assume the same original equations of motion for the eld and particles that interact
self-consistently. The model used here is very simplied, but the aim here is to
elucidate the basic principles and scaling behavior of such devices, not necessarily to
calculate what the exact dynamics, outputs, and parameters of a fully commercially
realized device will be.