  Plasma in the terrestrial magnetosheath is characterised by very weak
particle-particle collisions, so kinetic microinstabilities are thought to be
responsible for regulating the thermodynamics of the plasma. By exciting
electromagnetic waves, these instabilities redistribute free energy in velocity
space, moulding the velocity distribution function (VDF) into a lower energy
state. In the high-beta magnetosheath, relatively small perturbations to the
VDF can easily excite instabilities compared to in the low-beta inner
heliosphere. Since magnetic fields cannot do work on the particles, electric
fields mediate energy exchange between the electromagnetic field and the bulk
fluid properties of the plasma. We investigate signatures of non-ideal energy
conversion associated with turbulent fluctuations in the context of electron
and ion temperature anisotropy-beta instabilities, utilising over 24 hours of
data spread over 163 distinct intervals of in situ magnetosheath observations
from Magnetospheric Multiscale (MMS). We find that average energy conversion
into fluid flow is enhanced along instability boundaries, suggesting that
turbulence is playing a role in how free energy is redistributed in the plasma.
The work enables a quantification of the energetics which are associated with
the role of kinetic microinstabilities in regulating collisionless plasma
thermodynamics. This work provides insight into the open question of how
specific plasma processes couple into the turbulent dynamics and ultimately
lead to energy dissipation and particle energisation in collisionless plasmas.
