Dissipation and particle acceleration in collisionless shock waves

Earth's magnetic field forms an obstacle to the solar wind, generating a dynamic cavity around Earth known as the magnetosphere. As the solar wind flows over the magnetosphere faster than the local wave speed, a shock wave forms ahead of the magnetosphere in similar fashion to the sonic boom formed by a bullet or supersonic jet. Shock waves in space are also observed around supernovae, coronal mass ejections, and stars. In space, shock waves cannot dissipate energy with particle collisions, because the density is much too low. Instead, particle-scale electromagnetic plasma processes must be responsible. However, the balance of different phenomena that can contribute to heating and acceleration by shock waves is not yet fully understood.

Recent spacecraft observations and simulations have shown that turbulence and magnetic reconnection can occur within the transition layer of some shock waves. However, we do not yet know how significant these processes are to plasma heating in the broader system, or if they can contribute to the generation of high energy cosmic rays.

During this project, the student will use both in situ satellite data from spacecraft such as NASA's Magnetospheric Multiscale and Parker Solar Probe, and high-performance, parallelised plasma simulations. Using comparisons of data obtained by observational and computational methods, they will identify unusual plasma structures and characterise the turbulent transition region embedded inside shock waves. The student will have the opportunity to regularly engage with international teams and make significant contributions to our understanding of how shock waves repartition energy in space.