Time……….Tuesday, Aug 9th 2016, 3:30 -- 5:00 pm
Where……. Room 415, North Physics Building
Speaker….. Dr. Christopher H. K. Chen, Imperial College of London
Title……….. Turbulence and Instabilities in the Solar Wind: Recent Progress and Future Missions
Abstract:
The solar wind displays fluctuations over a broad range of scales, which are generally interpreted as a combination of turbulence and instabilities. The turbulent cascade is thought to transfer energy from large driving scales, down to small kinetic scales, where it heats the plasma. Instabilities are thought to be locally generated by the free energy in non-Maxwellian particle distributions, generating waves at similar scales as the turbulent cascade. In recent years, we have been able to learn a lot about these processes from new high resolution spacecraft instrumentation, and long data sets to enable large statistical studies. Here, I will present recent measurements of the turbulent cascade, describing properties such as anisotropy, critical balance, residual energy, intermittency, and the nature of the fluctuations. I will then describe the first multi-species measurements of the firehose and mirror instabilities, and the role they play in constraining the distribution of solar wind parameters. I will finish by describing some of the future missions we have planned to address some of the remaining questions, in particular the THOR spacecraft, which will make the highest resolution measurements of the near-Earth space environment to understanding turbulent plasma heating.
