This interdisciplinary project will incorporate the disciplines of Physics, Chemistry and Engineering. However the project is specifically housed within the Hope College Department of Physics and is intensely a physics development.
Our experiments and analysis over the past three years have resulted in a new understanding of how gas turns into plasma in very small gaps. We are currently seeking to understand our own finding that microgap discharge requires exactly twice the molecular collision rate as large gap discharge. We have also discovered that plasma initiates outside of microgaps and bleeds into them. Both of these Hope College discoveries have resulted in publications which are now resulting in more advanced research.
Optical spectroscopy is being used to identify the atomic and molecular transitions responsible for the optical emissions. We have found that long wavelength optical transitions are suppressed in microgaps and a major goal of the current work is to understand why that happens. The color of the glow discharge has been found to change when the microwave frequency exceeds the rate of collisions between atoms and electrons, and this transition will be another focus of study this year.
This research will include some classroom instruction on the research topic along with required group meetings. Hope students are expected to start working before the summer, and to continue into next year. A summary of the 42 hour training course (PHYS 495, Microwave Engineering and Device Physics) will be given prior to the start date and all accepted applicants are strongly encouraged to participate. Contact Prof. Remillard for details. Must have had a first course in electromagnetism (PHYS 122 or equivalent).
J.D. Campbell*, A. Bowman, III*, G.T. Lenters, and S.K. Remillard, "Collision and diffusion in microwave breakdown of nitrogen gas in and around microgaps," AIP Advances, 4, no. 1, 017119, (2014).
TJ Klein*, Cameron J. Recknagel*, Christopher J. Ploch*, and S.K. Remillard, "Microwave Breakdown of Low Pressure N2 Gas in Microgaps",Applied Physics Letters, Vol.99, no.12, 121503, (2011).
S. K. Remillard, A. Hardaway*, B. Mork, J. Gilliland*, and J. Gibbs*, "Using a re-entrant microwave resonator to measure and model the dielectric breakdown electric field of gases," Progress In Electromagnetics Research, Vol. B15, pp. 175-195 (2009).
The breakdown of air in small devices is not well understood, but poses a disruptive response of devices to high electric fields. High power microwaves are being used to induce dielectric breakdown in air in order to study the breakdown's dependence on pressure, diffusion length, temperature and gas composition.