Research

Extreme ultraviolet (EUV) lithography is currently one of the most advanced optical techniques used in semiconductor fabrication. It involves using high-powered lasers to convert molten tin droplets into plasma and to direct the emitted photons into a reflective semiconductor pattern. The reflected light then prints the pattern onto the semiconductor wafer. 

Current technologies operate with tin within the 13.5nm with a 2% bandwidth spectrum and have achieved 6% conversion efficiency. The Laboratory for Plasma Soft X-Ray Light Sources and Diagnostics is working to better understand the properties of tin plasma.

Plasmas inherently generate complex electric fields that are difficult to accurately simulate, yet these fields are central to determining the underlying reaction pathways and overall plasma behavior. Conventional diagnostic techniques, such as electrical waveform measurements and voltage probes, often lack sufficient spatial and temporal resolution or can perturb the very fields they aim to measure. 

This makes non-invasive approaches essential for capturing true plasma dynamics. Coherent laser-based diagnostics, such as electric-field-induced second harmonic generation (E-FISH), offer a powerful solution by enabling picosecond-resolved electric field measurements. The coherent nature of the signal allows it to be readily distinguished from plasma emission and efficiently transmitted to a detector, providing a robust, non-intrusive probe of local electric fields.

Carbon nanotubes (CNTs) are remarkable materials known for their exceptional strength, electrical conductivity, and thermal stability, making them important for next-generation technologies such as energy storage devices, lightweight composites, and biomedical systems. One of the most promising methods for producing CNTs at scale is Floating Catalyst Chemical Vapor Deposition (FCCVD), but a major challenge remains: only a very small fraction of catalyst nanoparticles actively participate in CNT growth. 

This research focuses on understanding how these catalyst nanoparticles form and behave in the gas phase during synthesis. Using advanced laser-based diagnostic tools, the project measures temperature fields, tracks iron atoms, and monitors nanoparticle size in real time. By improving control over catalyst formation, this work aims to make CNT production more efficient and reliable while also contributing new diagnostic approaches applicable to broader nanoparticle synthesis and plasma-based materials processing. This work is carried out in collaboration with Rice University

Nanosecond repetitively pulsed discharges (NRPDs) are a form of atmospheric-pressure plasma that can rapidly generate reactive species while avoiding excessive heating of the surrounding gas. Because of this unique behavior, they are promising for applications such as cleaner combustion, flow control, and advanced plasma-assisted technologies. 

During these discharges, the plasma can transition from a diffuse glow state to a highly ionized spark state, but the fast processes that drive this transition are still not fully understood. This research investigates how and why this change happens by capturing extremely fast measurements of electron density, electron temperature, and plasma structure using advanced imaging and laser-based diagnostics with sub-nanosecond time resolution. By combining optical emission spectroscopy, laser scattering, and high-speed streak camera imaging, the project tracks how ionization and filament formation evolve in real time. The goal is to better understand the physics behind glow-to-spark transitions in plasma discharges, which will help improve future plasma-based systems for energy, propulsion, and environmental applications.

2D materials such as transition metal dichalcogenides (TMDs) provide vast improvements in electrical and optical performance compared to conventional materials such as silicon for nanoscale devices. 

However, little is understood on how specific plasma parameters affect the materials optical and electrical properties. Nonlinear optical microscopy can be used to measure specific material properties to give a better understanding of how the plasma and material interact.

During hypersonic reentry, space vehicles must withstand extreme environments, making it critical to understand how high-temperature reactive gas flows interact with advanced TPS materials such as carbon-based composites and ultra-high temperature ceramics. 

While state-of-the-art laser diagnostics enable precise, non-intrusive measurements of gas-phase species and surface reactions, a key gap remains in accurately capturing and predicting the coupled, non-equilibrium interactions that govern ablation under real flight conditions.
Image credit: https://www.grc.nasa.gov/www/k-12/airplane/hmission.html

The Hypersonic Configurable Unit Ballistic Experiment (HyCUBE) is an innovative flight-testing platform designed to advance our understanding of hypersonic aerodynamics. By deploying CubeSat-like vehicles that are intentionally de-orbited, HyCUBE enables in-situ data collection during atmospheric re-entry across a wide range of Mach numbers and altitudes. 

Unlike traditional test methods, this approach offers a flexible and cost-effective means of conducting repeated or simultaneous experiments. HyCUBE systems can be instrumented to measure key phenomena such as temperature, pressure, radiative heating, plasma formation, and material response, providing new insights into high-speed flow physics. Beyond its scientific impact, the project also serves as a hands-on platform for training the next generation of engineers in hypersonic system design and flight testing.