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Katharina Stapelmann

Department of Nuclear Engineering (College of Engineering)

Assistant Professor

Burlington Laboratory 2114

Bio

Dr. Stapelmann studies the interactions of technical plasmas with biological systems on a macromolecular level. Her focus is on the characterization and optimization of plasma discharges used for biomedical applications and the understanding and improvement of plasmas used e.g. in medicine. The applications range from wound healing to air purification, sterilization of medical instruments as well as for planetary protection purposes. Furthermore, plasma-liquid interactions and plasma discharges in liquids belong to the repertoire.

Education

Ph.D. Electrical Engineering Ruhr University Bochum, Germany 2013

M.S. Electrical Engineering Ruhr University Bochum, Germany 2009

Publications

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Grants

Date: 05/01/21 - 4/30/24
Amount: $560,456.00
Funding Agencies: National Science Foundation (NSF)

The goal of this research program is to gain fundamental understanding of the multi-phase plasma-gas-liquid system by utilizing both theoretical and experimental approaches. The plasma breakdown and streamer development in steep gradients will be investigated dependent on realistic bubble geometries and as a function of applied voltage conditions. The multiphase interface tracking DNS code PHASTA has been well-established through a wide variety of two-phase flow problems. When coupled with the well-established plasma modeling and characterization code nonPDPSIM, it will give new insights into gas bubble formation and how the size and shape of the bubbles will influence the breakdown of the plasma. The experiment will allow the production of various well-defined bubble shapes and sizes, making it possible to investigate the dependency of the plasma breakdown on bubble geometries. The project will provide 1) the initial steps to combine high-resolution multiphase physics with electric fields and plasma physics, opening the opportunity to study fundamental plasma physics in a multiphase system, and 2) the experimental investigations to benchmark the simulations and to study how the polarity of the applied voltage pulses affects the streamer propagation in a bubble in liquids.

Date: 10/01/21 - 9/30/23
Amount: $370,000.00
Funding Agencies: US Dept. of Energy (DOE)

"There is arguably no other material that holds more potential for advancing future nuclear power applications than molten salts. Their advantageous thermodynamic and chemical properties could help close the fuel cycle and revolutionize the way in which nuclear reactors operate. However, important technical challenges and proliferation concerns must be solved before molten salts can reach commercial utility. Perhaps most urgently needed is a reliable technique for real-time quantification of molten salt composition. Many future MSR designs require in situ chemical processing to continuously remove neutron-absorbing fission products and corrosion-causing impurities (i.e., oxygen and water). Complementing chemical removal, many MSR designs also require some level of periodic refueling, which will change both the quantity of fissile material and its isotopic concentration. Salt-cooled reactors will also require process monitoring to alert operators in the event of a nuclear fuel breach. Commercial scale pyroprocessing of used nuclear fuel must also have adequate process monitoring for controlling the rate of actinide removal. Furthermore, the unprecedented mobility of nuclear material within flowing molten salts poses serious problems for material accounting. Unlike solid fuel rods, actinide-containing molten salts are continuously mixed and transported in a liquid state, which makes them fundamentally more susceptible to unauthorized extraction. Therefore, future molten salt accounting will require a remote chemical-isotopic sensor that can operate in a high radiation environment, thus greatly limiting direct human involvement. Although the leading candidate method for real-time material accounting (laser-induced breakdown spectroscopy, LIBS) has progressed in recent years, its inherent technical challenges may limit widespread commercialization. The overarching objective of the proposed research is to investigate a new method for quantifying nuclear materials in molten salts using a technique we call “plasma-bubble spectroscopy” (PBS). The strategy of our proposed technique (Figure 1) is to transform small quantities of bulk molten salt into a low-density gaseous bubble using an impulsive spark discharge or ultrafast laser breakdown. This molten salt bubble is then converted into a dilute plasma by means of a glow discharge, whose sharp atomic emission lines can be spectrally analyzed with sub-angstrom resolution. The proposed technique addresses several critical challenges facing materials accounting in molten salts: online monitoring capability, shot-to-shot stability, optical clarity, and the possibility of uranium isotopic quantification. Our long-term vision is to enable a low-cost, low-maintenance, high throughput device that can operate in the extreme conditions found in MSRs and advanced fuel reprocessing."

Date: 09/01/22 - 8/31/23
Amount: $74,010.00
Funding Agencies: US Dept. of Energy (DOE)

The aim of this research is to capture time- and space-resolved behavior of breakdown initiation and development in water with gas bubbles injected between the electrodes when excited with microsecond voltage pulses. The results will be directly compared to our previous results from a PCRF collaboration on the development of an electrical discharge in a gas bubble immersed in liquids with different conductivities when excited by nanosecond voltage pulses. For nanosecond regimes, cavitation seems to play a major role in plasma breakdown for low conductivities and discharge initiates at an electrode. On microsecond timescales, where cavitation does not play a role, it has been hypothesized that breakdown in water occurs first in bubbles on or near the electrodes, pre-existing or formed thermally. Hence bubble injection is expected to influence discharge initiation. Much of the recent work has been focused on shorter (nanoseconds) and longer (>100 microseconds) time scales. As part of a DoE-NEUP fellowship project, we are developing the capability to perform optical emission spectroscopy in gas bubbles immersed in molten salt. In another project, we are using gas bubbles immersed in water to fix nitrogen and produce N fertilizer on demand. For both projects, the capture of spatial and temporal resolution of streamer propagation and spectra is fundamental. By imaging the streamer propagation in bubbles in liquids we aim to determine 1. The difference in breakdown initiation on microsecond and nanosecond time scales with and without injected gas bubbles 2. Whether the injected bubbles influence discharge initiation at the microsecond time scales.

Date: 02/17/20 - 6/30/23
Amount: $656,250.00
Funding Agencies: Game-Changing Research Incentive Program for Plant Sciences (GRIP4PSI)

Enabling the next generation of sustainable farms requires a paradigm shift in resource management of the two most critical agricultural inputs for food production: water and nitrogen (N) - based fertilizer. Inefficient management of these resources increases food production costs, decreases productivity, and impacts the environment. An integrated approach is needed to improve the sustainability and efficiency throughout the production chain. Emerging (bio)electrochemical (BEC) technologies offer alternatives to conventional, fossil-fuel intensive N fertilizer production. Recently our team has demonstrated two game-changing BEC technologies: 1) microbial conversion of nitrogen gas into ammonium, and 2) plasma generation of N species (e.g., nitrate, nitrite) and other reactive species in water for fertilization and anti-pathogen benefits. We will integrate these technologies to produce BEC, N-based fertilizer, and with advanced sensor and delivery systems, we will precisely supply fertilizers for sustainable precision agriculture. Our proposed approach focuses on the development of a novel “BEC fertigation on demand system” by using sensor-driven data and molecular analyses to investigate BEC fertigation impact on the plants’ growth, adaptation, and microbiome; its impact on food safety and quality, and its economic feasibility for on-farm deployment.

Date: 07/01/20 - 6/30/23
Amount: $468,000.00
Funding Agencies: US Dept. of Agriculture - National Institute of Food and Agriculture (USDA NIFA)

Our goal is to develop an innovative in-package plasma manufacturing technology for improving safety, maintaining quality and nutrients, and extending shelf-life of fresh produce while being energy, water, and resource-efficient.


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