2022 Fiscal Year Research-status Report
Exploring availability of plasma-induced solvated electrons: formation and transport
| Project/Area Number |
22K14174
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| Research Institution | Tohoku University |
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Principal Investigator |
劉 思維 東北大学, 流体科学研究所, 助教 (60902228)
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| Project Period (FY) |
2022-04-01 – 2025-03-31
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| Keywords | solvated electrons / plasma flow / time-resolved |
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| Outline of Annual Research Achievements |
This project innovatively proposes the plasma flow in the liquid as a potential high-effective source for solvated electrons. In order to elucidate the coupling mechanism between solvated electrons and plasma flow, it is a severe challenge to directly observe solvated electrons due to the super activity and short lifetime of solvated electrons. In FY 2022, dechlorination was selected as an indicator of solvated electrons in the experiment. The results confirm the generation of chloride ions which remained in the target solution with a useable mass concentration that eventually increases exponentially when the treatment time increase. These results validate the potential for monitoring the distribution of solvated in the solution by specific indicators. In the next step, the flow behavior caused by the concertation difference would be studied and discussed.
By combining a streak camera and a spectrometer, it is possible to resolve the spectral characteristics of plasma flow into continuous time sequences. The time-resolved spectra at the gas-liquid interface were successfully achieved with a temporal resolution of less than 1 microsecond and a wavelength resolution of 5.3 nm. Two main bands of light emission can be recognized, which correspond to the instants of the voltage application and reverse. The contents of wavelengths for the two bands show no difference, however, the total intensity, as well as the width, changes significantly. The results highlight the origin of the solvated electrons from plasma flow rather than the accumulation of charge in the liquid.
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| Current Status of Research Progress |
Current Status of Research Progress
1: Research has progressed more than it was originally planned.
Reason
1. It is necessary to visualize the formation and transport of the solvated electrons generated by plasma flow. In the original proposal, a series of discrete grating filters are planned to be used to cut the images into different wavelengths. The quality of the images such as the wavelength resolution is limited by the number of filters and their performance. In FY 2022, we combined the streamer camera with the spectrometer and overcame the difficulty of synchronization. Time-resolved spectra of the plasma flow were successfully obtained.
2. Despite the dechlorination was selected as an indicator of solvated electrons. Different indexing approaches to evaluate the solvated electrons were tested by experiments in FY 2022. The protocols were constructed and the performances were compared, which may provide guidance for further studies.
3. An image processing program was developed to collect, analyze, and display optical images from the high-speed camera. It sufficiently helps the post-process of the data and can be used throughout this project.
Based on the above facts, the project is progressing more smoothly than initially planned.
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| Strategy for Future Research Activity |
In FY 2023, it is necessary to improve the above-mentions techniques and provide detailed discussions on the coupling mechanism of solvated electrons and plasma flow. (1) The behavior of solvated electrons by analyzing the indicators will be furtherly studied, therefore, it is possible to understand the distribution of solvated electrons. Moreover, the micro-structure of plasma flow and its effect on the solvated electrons formation should be considered. (2) It is also important to directly measure the solvated electrons and study their response to plasma flow. We expect to find and select the dominant wavelengths from the time-resolved spectra at different times. Then the scattering of solvated elections will be studied under different incident light signals. (3) The reconstruction of solvated electrons in the media will be studied and we are aiming to establish a numerical method for the image reconstruction based on the experimental results.
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| Causes of Carryover |
There is a small amount of budget remaining which is difficult to be fully executed. It will be used together with the main budget in FY 2023.
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