  A non-perturbative method is introduced to measure the particle-particle
interaction strengths and in-situ confinement for a vertically aligned dust
particle pair in a complex plasma. The intrinsic thermal motion of each
particle is tracked, allowing the interaction strengths and confinement in both
the vertical and horizontal directions to be determined simultaneously. The
method is validated through quantitative agreement with previous measurements
of the non-reciprocal interaction strength in the vertical direction, the
horizontal ion wake attraction, and the charge reduction and heating of the
lower particle when located in the wake of the upper particle. The experiment
also verifies both theoretical and numerical predictions for the ion wake
potential by investigating the ratios among the interaction strengths in the
vertical and horizontal directions, as well as in the up- and down-stream
directions at varying powers. The upstream potential is shown to be asymmetric
with unequal screening lengths in the vertical and horizontal directions,
implying a subsonic ion flow at low rf powers. Additionally, it is shown that
the ratio between the down and up-stream strengths in the vertical direction
remains constant at high power, then increases at low power, in agreement with
the theoretically predicted increase in the magnitude of the wake potential as
the Mach number decreases. Finally, the measured ratio of approximately 5
between the downstream and upstream strengths in the horizontal direction is
shown to agree with simulations conducted employing similar plasma parameters.
