Hope College Physics Department
Research Experiences for Undergraduates
|Project Title:||1 Microwave Probing
of the Nonlinear
Electrodynamics of Tl2Ba2CaCu2O
2 Microwave Induced Ozone Production of Stratospheric Gas Discharge
|Student's Home Institution:||Hope College|
Dr. Stephen Remillard
|Source of Support:||1This material is based upon work
supported by the
Foundation under NSF-REU Grant
2 This material is based upon work supported by the National Science Foundation under NSF-REU Grant No. PHY-0452206, Michigan Space Grant Consortium, and National Aeronautics and Space Administration.
1An understanding of the nonlinear electrodynamics of TBCCO superconductors is crucial to their ultimate application in microwave electronics. Surface resistance and its power dependence of TBCCO thin film wafers was measured before and after hole auto-doping at various temperatures. After nitrogen anneals, ranging from 250° - 350°C, surface resistance increased with doping, and the films moved to a higher nonlinear regime. Harmonic interference and intermodulation distortion (IMD) was measured in TBCCO patterned strip-line resonators. IMD peaked near 84 K, indicating that the shrinking superfluid density is more sensitive to current excitation. The generated intermodulation power is proportional to (Hmax)3.67, where Hmax is the maximum surface magnetic field. The location of second order harmonics was found to be different than that of third order within the patterned resonator.>
2Plasma is created by the acceleration of free electrons by an electric field. Breakdown is induced in a quarter wave resonator at 1.8 GHz. The perturbation theory has been applied to compare the electric field in the plasma region at breakdown. We will continue to study the response of controlled gas with microwaves, leading a better knowledge of stratospheric responses and breakdown kinetics. This summer’s project primarily focused on determining dependent and independent variables of collision theory, in respect to the stratosphere, by the analysis of nitrogen, oxygen, and air Paschen curves. Mass spectrometry is currently being setup for analysis of the plasma components, and is expecting to aid in determining when ozone is actually produced. This will move us closer toward the ultimate goal of restoring depleted stratospheric ozone using high power microwaves.
"Using a re-entrant microwave resonator to measure and model the dielectric breakdown electric field of gases," S. K. Remillard, A. Hardaway, B. Mork, J. Gilliland, and J. Gibbs, Progress In Electromagnetics Research, Vol. B15, pp. 175-195 (2009).
"Dielectric Breakdown in Air Components at Microwave Frequencies under Stratospheric Conditions", Alejandro Hardaway, Jake Gilliland, and Joseph Gibbs, West Michigan Regional Undergraduate Science Research Conference, Van Andel Research Institute, Grand Rapids, November 1, 2008.
"Dielectric Breakdown in Air Components Under Stratospheric Conditions", S.K. Remillard, A. Hardaway , Brian Mork, and Jake Gilliland, Michigan Space Grant Consortium Annual Conference, Ann Arbor, Oct. 18, 2008.