  The effect of a perfectly conducting planar boundary on the average linear
momentum (LM), angular (momentum (AM), and power of a time-harmonic
statistically isotropic random field is analyzed. These averages are purely
imaginary and their magnitude decreases in a damped oscillatory manner with
distance from the boundary. At discrete quasi-periodic distances and
frequencies, the average LM and AM attain their free-space value. Implications
for the optimal placement or tuning of power and field sensors are analyzed.
Conservation of the flux of the mean LM and AM with respect to the difference
of the average electric and magnetic energies and the radiation stresses via
the Maxwell stress dyadic is demonstrated. The second-order spatial derivatives
of differential radiation stress can be directly linked to the electromagnetic
energy imbalance. Analytical results are supported by Monte Carlo simulation
results. As an application, performance based estimates for the working volume
of a reverberation chamber are obtained. In the context of multiphysics
compatibility, mechanical self-stirred reverberation is proposed as an
exploitation of electromagnetic stress.
