Understanding the sun is important for assessing & predicting it's effect on our climate & potential catastrophes from solar storms
Lead Research Organisation:
Aberystwyth University
Department Name: Inst of Mathematical and Physical Sci
Abstract
Similar to fluid turbulence, turbulence in fully ionzed magnetized gases is highly non-linear. The existence of magnetic field and charged particles make the understanding of plasma turbulence substantially more difficult. Turbulence in space plasmas is even more challenging to study due to two factors: 1 space plasmas are often with large flow speeds. 2: the sampling of such plasmas is difficult and often limited to single satellite observation. Hence multi-satellite data, when available, will be highly valuable for the study of space plasma physics. Since most astrophysical materials are in plasma state, the astrophysical significance of plasma turbulence study is obvious.
The project will use multi-spacecraft data analysis tools such as k-filtering and phase-differencing techniques to investigate the property of solar wind and space plasma turbulence at (or sub-) ion inertial and gyration scales. The two techniques will be complimentary to each other. While the k-filtering technique (already developed and conducted in our group) is able to provide statistically averaged information of plasma turbulence at ion inertial and gyration scales, results obtained from the technique lack important information of the minority plasma disturbance contributors to the plasma turbulence at the said scales. The phase-differencing technique (which is under development in our group) however is capable of providing the detailed information of individual wave packets including the direction that wave packets are propagating, scaling laws of these wave packets and the wave number space anisotropy. This will offer new opportunities for investigating solar wind turbulence since the treatment of large number of wave packets will reveal ingredients of plasma turbulence with statistical significance. The project aims to reveal the significance of Alfven wave turbulence, kinetic fast and slow wave turbulence at sub-ion scales in the solar wind plasma.
The project will use multi-spacecraft data analysis tools such as k-filtering and phase-differencing techniques to investigate the property of solar wind and space plasma turbulence at (or sub-) ion inertial and gyration scales. The two techniques will be complimentary to each other. While the k-filtering technique (already developed and conducted in our group) is able to provide statistically averaged information of plasma turbulence at ion inertial and gyration scales, results obtained from the technique lack important information of the minority plasma disturbance contributors to the plasma turbulence at the said scales. The phase-differencing technique (which is under development in our group) however is capable of providing the detailed information of individual wave packets including the direction that wave packets are propagating, scaling laws of these wave packets and the wave number space anisotropy. This will offer new opportunities for investigating solar wind turbulence since the treatment of large number of wave packets will reveal ingredients of plasma turbulence with statistical significance. The project aims to reveal the significance of Alfven wave turbulence, kinetic fast and slow wave turbulence at sub-ion scales in the solar wind plasma.
Organisations
People |
ORCID iD |
| Xing Li (Primary Supervisor) | |
| Owain Walker (Student) |
Studentship Projects
| Project Reference | Relationship | Related To | Start | End | Student Name |
|---|---|---|---|---|---|
| ST/N503915/1 | 01/10/2015 | 31/03/2021 | |||
| 1645805 | Studentship | ST/N503915/1 | 01/10/2015 | 30/09/2018 | Owain Walker |
| Title | Phase Differencing Code using Simplistic Power Recognition Techniques |
| Description | Extracting wave-packets at specific frequencies from a signal using wavelet analysis. Then, calculating the phase difference between wave packets of this first reference signal and wave packets from other signals. By comparing four signals e.g. four magnetic field signals from the Cluster satellites, a 3-dimensional wave vector can be calculated giving the direction of travel of a wave, fluctuation or structure in the solar wind. The method of locating peaks in the re-constructed signal at specific frequencies is quite simplistic but the method works well enough to give suitable results. |
| Type Of Material | Data analysis technique |
| Year Produced | 2018 |
| Provided To Others? | No |
| Impact | An improved method utilising image processing techniques could be used. |
| Title | Phase Differencing Code utilising Image Processing Techniques |
| Description | Rather than using a simplistic method to locate peaks in reconstructed time series, peaks are located earlier in the wavelet power spectrum of the data series. This method could be used to locate larger structures rather than smaller smaller structures. Work is still in progress. |
| Type Of Material | Data analysis technique |
| Year Produced | 2018 |
| Provided To Others? | No |
| Impact | Much more robust way of locating wave packets in a signal. With the earlier simplistic method of locating wave packets, it is more difficult to assess whether a peak in signal (which indicates a wave packet) is significant or not. |
| Title | Phase Differencing Diagnostic Tool |
| Description | For use with the Phase Differencing Code using Simplisitic Power Recognition Techniques. A method of highlighting wavepackets and their location on dispersion (w-k) plots and Plots of angle between wave vector and background magnetic field plots (or other plots as well). It is a useful way of recognising when certain wave packets are giving erronous results or outliers on dispersion and angle between k an B plots. |
| Type Of Material | Data analysis technique |
| Year Produced | 2018 |
| Provided To Others? | No |
| Impact | Recognised that simplistic code was not efficient in recognising peaks in power (that is wave packets) accurately. |
| Description | Research Presentations at Group Meetings |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | Local |
| Primary Audience | Postgraduate students |
| Results and Impact | Group meetings allow PhD students in the department to give presentations outlining their progress on their project. The audience includes other PhD students within the department and lecturers. Problems can be discussed and new ideas proposed to help PhD students proceed effectively. It is also good practise for attending conferences in future. I have attracted interest from a lecturer in the department to assist with improvements to my analysis techniques. |
| Year(s) Of Engagement Activity | 2015,2016,2017,2018 |