Plasma Science Research Group (PSRG)

Project Lead(s):

Dr. Scott J. Doyle

About the project

It is known that fundamental electron transport limits across plasma-liquid interfaces inhibit both the power efficiency and hydrogen yield in direct plasma driven water electrolysis. It is possible to remove these transport limits, and significantly increase the Faradaic efficiency, by operating at lower pressures (1 - 10 Torr) employing saturated water vapor discharges. To maintain the hydrogen yield at lower pressures the reactor volume must increase, necessitating novel source and power coupling designs. One novel approach involves the use of low-frequency toroidal transformed coupled plasma sources -typically employed as remote plasma sources within the semiconductor industry. By optimising the source topology, multi-scale chemical conversion sources may be employed either in-situ to reduce harmful emissions at the producing site or installed as dedicated energy storage platforms. Further enhancements are possible via the use of electromagnetic control schemes, including multi-harmonic driving voltages and asymmetric magnetic topologies. Such advanced real-time control techniques are critical to achieving high efficiencies, high yields, and chemical selectivity in next-generation plasma-driven electrolysis and chemical synthesis reactors.

List of published outputs

Funded through the Aberdeen Centre for Energy Transition

Project Lead(s):

Dr. Scott J. Doyle
Dr. Panagiotis Kechagiopoulos

About the project

In-Situ Resource Utilization (ISRU) refers to the concept of extracting, purifying, and utilising resources at an off-world mission site rather than transporting everything needed from Earth. ISRU is particularly relevant for space exploration and long-term habitation missions where transporting such resources from Earth is too costly or impractical.

Water is Life: The Lunar Crater Observation and Sensing Satellite (LCROSS) detected many useful materials present in the Lunar regolith (soil), of the volatile species present in Lunar regolith, water is of particular interest. Water is essential to long term human habitation, for drinking, for food rehydration, for hygiene, for radiation shielding, and can provide oxygen and hydrogen for fuel cells. Splitting water into oxygen and hydrogen also provides the necessary propellants for chemical and electrical propulsion systems, reducing the need to ship heavy rocket fuel from Earth. Purified water is a mission critical resource, unlocking the capability to produce water in-situ will ensure a sustained human presence of the Moon and take us one step closer to the exploration of deep space. By exposing Lunar soil to carefully designed plasma discharges it is possible to heat and extract useful volatiles from the soil and break these volatiles into atoms. Hydrogen and oxygen atoms recombine back into pure water, which is collected, while the other impurities are filtered out with the rest of the Lunar dust. In comparison to other methods, plasmas offer a high degree of control and selectivity, they are versatile, plasma sources are lightweight and self-contained, and are easily scalable.

The Challenge: We know that plasmas can extract and purify water under ideal conditions, but can they perform under the challenging and highly variable conditions found on the Moon and beyond? Plasma sources are often built to operate in strictly controlled conditions, not the highly variable conditions found with each new scoop of Lunar regolith. Another major unknown is the accumulation of Lunar dust within the plasma source. Dust accumulates a static charge, and can significantly alter how the electrons (and hence the chemistry) will proceed within a plasma. Understanding how to maintain a uniform plasma, and produce the highest yield of pure water, necessitates a deeper understanding of the complex electron, ion, neutral, and molecular dynamics, and how these may be controlled and optimised in the 'dirty' and 'dusty' Lunar conditions.

List of published outputs

Funded by UKRI - EPSRC Ref. EP/X000931/1

Project Lead(s):

Dr. Scott J. Doyle
Prof. John. E. Foster
Dr. Panagiotis Kechagiopoulos

About the project

A capacitively coupled RF micropropulsion source showing the plasma density distribution, electron source rates, and electron fluxes. Grey material is grounded aluminium, blue is alumina dielectric, red is copper electrode, dashed white indicates RF phase-averaged sheath edge.

Recently, there has been a growing interest in alternative propellants for electric propulsion systems[1-3]. For high-power, deep-space satellites, this search has focused on a replacement for xenon, with leading contenders being iodine and bismuth. For 'off-the-shelf', academic, and commercial satellites (particularly micro-satellites) the search for alternative propellants is driven by a requirement for safety, affordability, and simplicity, and includes many molecular substitutes such as ammonia, water, peroxide, ethanol, nitrous oxide, and carbon dioxide. Notably, such volatile species are also abundant in comets and asteroids, raising the possibility of In-Situ Resource Utilisation (ISRU) refueling of platforms capable of extracting and employing such molecular propellants. While numerous studies have addressed the need to replace xenon, there have been significantly fewer studies into molecular propellants in electric propulsion (EP) systems. Ammonia and water in particular have not been well studied, despite presenting a storage-dense, cheap, and abundant (both terrestrially and in-situ) propellant solution for satellite operations. This PhD studentship addresses this shortfall in the literature by numerically modelling RF-driven ammonia and water molecular discharges within an electrothermal propulsion context. Numerical modelling of the power deposition and molecular dissociative pathways in micro-RF plasma sources will facilitate a broader understanding of the pros and cons of molecular propellants within the micro-EP environment, and act as a staging point for future studies in more complex geometries and reaction mechanisms.

List of published outputs

Funded by the US Air Force Office of Research & Development

Project Lead(s):

Prof. Angel Cuesta Ciscar
Dr. Panagiotis Kechagiopoulos

About the project

Led by Professor Angel Cuesta Ciscar from the University's School of Natural and Computing Sciences, and Dr Panagiotis Kechagiopoulos from the School of Engineering, the project explores how carbon dioxide could be converted into hydrocarbons for energy use through plasma electrocatalysis. Through this process we create a controllable electrochemical reaction by applying a voltage between two electrodes in a weakly ionised gas, resulting in the reduction of CO2 and the oxidation of hydrogen. This combination of plasma-catalysis and electrocatalysis will allow the use of renewable electricity generated by renewable sources to power a plasma electrolyser, in an entirely new process that would efficiently convert CO2 back to hydrocarbons, reducing CO2 emissions as part of a circular economy model.

List of published outputs

Funded by UKRI - EPSRC Ref. EP/X000931/

Project Lead(s):

Dr. Scott J. Doyle

About the project

Increasing available onboard electrical power in telecommunication satellites has driven interest in a new wave of high-power electric propulsion systems. Mature high-powered propulsion systems, Similar to a tokamak, transformer-coupled propulsion sources employ primary coil antennae to induce a secondary current in a toroidal plasma column. Ferrites are employed to enhance the coupling efficiency and control discharge topology. Low radio frequency (250 - 1000 kHz) power is ohmically coupled within the plasma column, facilitating efficient and homogeneous neutral gas heating. Transformer coupled propulsion sources offer a scalable, robust, and cost-effective method of coupling high-wattage electrical power into a wide range of propellants, offering high thrust (>1 N), mid-specific impulse (100 - 300 s) solutions for LEO, GSO, Lunar transfer orbits, and beyond.

ACCEPTING PhD APPLICATIONS

List of published outputs

Funded through the Aberdeen Centre for Energy Transition

Project Lead(s):

Dr. Panagiotis Kechagiopoulos
Dr. Alan McCue
Dr. Scott J. Doyle

About the project

Valorisation efforts of biogas, the product of biomass anaerobic digestion, have intensified due to a global rise in the implementation of waste management technologies. Dry reforming allows for simultaneous conversion of the main components in biogas (primary greenhouse gases CH4 and CO2) towards syngas (H2 and CO mixture), the latter either purified as clean hydrogen or upgraded to biofuels.

This project investigates the production of bio-based hydrogen through plasma-catalytic dry reforming of biogas. Plasma-catalysis, enabling the activation of highly stable molecules like CH4 and CO2 even at ambient conditions, can drive the electrification and enhance the sustainability of dry reforming (replacing the need for thermal energy supply, typically applied in the chemicals industry). With almost instantaneous transient response and inherent modularity, plasma-catalysis is particularly suited for the use of electricity from fluctuating renewable resources.

List of published outputs

Funded by The School of Engineering Development Trust