Research
Plasma turbulence
Plasma turbulence shows many features of hydrodynamic turbulence, like an energy cascade. However, plasma turbulence has some additional intrinsic length scales due to the electromagnetic as well as particulate nature of plasmas. This leads to many new and interesting features at the kinetic scales. Recent observations point to a change in the nature of turbulent cascade at sub-ion scales. We have investigated this by means of PIC simulations and found the dominance of kinetic Alfven wave dynamics at these scales (Ref.).
Numerical simulations of plasma turbulence show the formation of very thin current sheets, as shown in the video below. We found that the thickness of these current sheets is of the order of kinetic scales, which is also observed in solar wind observations. The solar wind magnetic field is measured by the NASA-Magnetospheric Multiscale Mission (MMS). In this data we identify sharp changes in the current density and identify intermittent current sheets. The thinnest scales of these structures turn out to be of ion skin depth or smaller.
Magnetic reconnection
Magnetic reconnection is a phenomena where magnetic field lines are broken and reconnected. This is accompanied by conversion of magnetic energy into plasma energy. Magnetic reconnection is behind several phenomena, like for ex. solar flares. Magnetic island merging also proceeds via reconnection. Our simulations like below show that reconnection rate is determined by both small-scale kinetic physics and also large-scale MHD physics. The magnetic island merging simulation is shown below
Fusion plasma
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