Shining light on cold atmospheric plasmas and their interaction with liquids
Lead Research Organisation:
Queen's University Belfast
Department Name: Sch of Mathematics and Physics
Abstract
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Publications
McDonnell C
(2022)
Optical diagnosis of a kHz-driven helium atmospheric pressure plasma jet
in Journal of Plasma Physics
| Description | We have carried out extensive measurements on the properties of atmospheric gas jets relevant to the project. This includes ultra-fast optical imaging on nanosecond time scale that shows the velocity of the plasma bullets. We have also looked at atomic and molecular optical emission features to explore the gas and electron temperatures and have also taken Raman scattering data to measure gas temperatures. The findings show a lower than expected electron temperature and this may be associated with the difficulty in observing optical Thomson scattering. We have additionally used the observation of optical line ratios and splitting to observed the macroscopic electric field in the plasma bullets. We are closely working on obtaining upper limits to the electron density by reducing the background noise in the Thomson scatter experiment. The latest result is that we can assign an upper limit of around 10^13 cm^-3 to the electron density. Work on absolute calibration of our fast cameras combined with imaging using narrow band-pass filters has allowed us to measure the density of several He-like excited states, providing a key comparison point with simulations. Further work, using Stark spectroscopy has allowed us to measure the electric field in these plasma bullets, finding that fields up to 20 KV/cm are present, with the field value rising towards the end of the plume. This is important as the presence of the field has been shown to induce electroporation in cells, allowing reaction nitrogen and oxygen species (RONS) to penetrate and kill cells such as bacteria. A summary of the work so far, on absolutely calibrated imaging and electric field measurements along with bullet speed dependence on applied voltage and gas flow is being prepared for publication, with submission expected in the spring of 2022. |
| Exploitation Route | They will help understand the plasma conditions that are needed as part of modelling the interface between plasmas and surfaces. We have had some preliminary contact with a local company interested in working on surface modification. More recently we have started to plan with the school of pharmacy to implement diagnostics in real time on the gas-jets they are using in the laboratory to irradiate various bio-samples. We are also part of a consortium that has submitted a proposal to HEA (Higher Education Authority in RoI) for an Ireland wide programme of research into related plasmas. We expect to hear an outcome early in 2022. |
| Sectors | Healthcare,Manufacturing, including Industrial Biotechology,Pharmaceuticals and Medical Biotechnology |
| Description | As a result of this work, we have had some preliminary talks with a company based in NO who make stoma bags and are interested in plasma treatments as a way of improving adhesion. We have started to work with pharmacy to establish a test-bed where the physical characteristics of the plasma jets used in pharmacy work can be measured in-situ. More recently, we have become part of a consortium across Ireland, including pharmacy, in QUB to apply for funding for a research network that will study similar plasma systems across a range of applications from agricultural to medical. The application is to the Higher Education Authority in the Republic of Ireland and we are awaiting the outcome of this. |
| First Year Of Impact | 2020 |
| Sector | Healthcare,Pharmaceuticals and Medical Biotechnology |
| Impact Types | Cultural,Societal |
| Description | Queen's University Belfast Core Equipment Call 2022 |
| Amount | £871,595 (GBP) |
| Funding ID | EP/X034887/1 |
| Organisation | Engineering and Physical Sciences Research Council (EPSRC) |
| Sector | Public |
| Country | United Kingdom |
| Start | 12/2023 |
| End | 07/2024 |
| Description | COMSOL modelling |
| Organisation | Seikei University |
| Country | Japan |
| Sector | Academic/University |
| PI Contribution | Dr Murakami has been working with our students on modelling of our plasma jet results and we have supplied the experimental data. |
| Collaborator Contribution | Dr Murakami has been working with our students on modelling of our plasma jet results. He has a model of the plasma that can be adapted to out case |
| Impact | A new version of COMSOL modules has been supplied to out PhD students. |
| Start Year | 2019 |