Engineering Commons^™

Understanding The Impact Of Divertor And Main Chamber Ion Fluxes On Divertor Closure In The Diii-D Tokamak, Kirtan M. Davda

Doctoral Dissertations

The diverted tokamak redirects extreme heat and particles to targets, a plasma-facing component designed for such loads. Here, the local fluxes produce strong particle recycling and sputtering. Recycled neutrals can “leak” into the region between the core and wall, the scrape-off-layer (SOL), impacting plasma performance. Increasing divertor closure can reduce leakage by containing neutrals within the divertor. However, there exists a need to quantify divertor baffle restrictions and understand closure directly from empirical data as opposed to indirectly through modeling.

Our study introduces the Geometric Restriction Parameter (GRP) based on simplifying neutral transport to ballistic pathways. Specifically, it considers the …

Tunable Catalysts And Electrodes With High Material Utilization And Durability For Hydrogen Production, Lei Ding

Doctoral Dissertations

Hydrogen, the future energy carrier, has gained extensive attention due to its advantages of high energy density, low weight, and zero-carbon emission. So far, hydrogen has been widely used in various fields including transportation, oil upgrading, metal refining, etc. Most hydrogen is currently produced from fossil fuels, which can cause serious environmental problems. Water electrolysis was proposed to produce clean hydrogen with carbon-free emission and only byproduct of oxygen. Among various water electrolyzer devices, the proton exchange membrane electrolyzer cell (PEMEC) shows great potential to produce green hydrogen by integrating renewable sources (solar, wind, etc.) due to its advantages of …

Thermal Runaway Of Li-Ion Batteries: Triggering, Emission, And Mitigation, Liwen Zhang

Doctoral Dissertations

In the contemporary landscape, lithium-ion batteries (LIBs) are key components powering a wide array of electronic devices and electric vehicles (EVs). As society increasingly relies on these batteries for their efficiency and functionality, understanding and mitigating potential risks, such as thermal runaway (TR) events, become imperative. The objective of this dissertation is to comprehensively understand TR characteristics of LIBs through a combination of experiments and numerical simulation, thereby enhancing battery safety, refining design standards, and providing insights and guidelines for the prevention and management of TR events.

Firstly, this dissertation explores the safety regime of LIBs TR through a computational …