ECLIPSE/Collaborative Proposal: Studying Microwave-Plasma Interactions at Solid Interfaces Using Microwave Microstrip Architectures

This project explores the effect of microwave radiation on low temperature plasmas composed of electrons, ions, and neutral particles. Low temperature plasmas are routinely used in fields from manufacturing to medicine to clean energy technology, and it is desirable to be able to modify a plasma in real-time based on the requirements of the application at hand. A promising method of changing plasma conditions is through the use of microwave energy. Microwave fields are often used in plasma science for diagnostic measurement and as a means of creating and sustaining plasmas. However, relatively little is known as to how microwaves can be used to augment and modify plasmas created by other means. In this project, the effect of highly-focused microwave radiation will be studied in order to develop an improved understanding of microwave coupling into plasmas with the goal of providing a means of predictably changing plasma conditions. This work is supported through the ECosystem for Leading Innovation in Plasma Science and Engineering (ECLIPSE) program as a collaboration between the State University of New York at Buffalo and Texas Tech University. This project will design and develop a set of microwave stripline and microstrip structures aimed at different microwave frequencies and adapted specifically to the plasma conditions found within different plasma types. The interaction of focused microwave fields with laser induced plasmas and reduced-pressure glow discharges in the proximity of solid interfaces will be studied by real-time electrical impedance and vector network measurements, optical emission spectrometry, tunable diode laser absorption spectroscopy, and Thomson scattering measurements. These measurements will be used to calculate fundamental parameters, such as electron number density and temperature, Boltzmann equilibria excitation temperatures, ionization temperatures, rotational temperatures, and vibrational temperatures. A major focus of the project will be to determine how interactions with microwaves alter these fundamental plasma parameters, and thereby to understand how microwaves perturb the different energy pathways in the plasma. The outcomes of the proposed work will include an improved understanding of microwave coupling in plasmas. This can be exploited in order to create improved means of optimizing microwave/plasma interactions that will lead to the development of new energy efficient systems and technologies. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.