Quantum turbulence is a conceptually simple form of turbulence, consisting of a
tangle of quantised vortex lines. It provides a model system, through which it may
be possible to understand features of the complex and not yet fully understood
classical turbulence. A novel detector made from arrays of custom-designed tuning forks was developed
and used to investigate properties of excitation beams and quantum turbulence in
superfluid 3He-B at temperatures below 200 µK. The detector was constructed
from 5 arrays of 5 tuning forks mounted in a copper block to create a 25 pixel
square detector of excitation flux. The detector was situated in a cell such that
it could be illuminated with a beam of thermal excitations, and that turbulence
could be generated in the path of the beam, which will cast a shadow on the face.
Characterisation of the detector response to beams generated by the black-body
radiator and source wire were performed. We observe that the beam generated
by a black-body radiator appears approximately symmetric, consistent with being
emitted from a point-source of excitations. In addition to this we find that the
profile of the beam generated by the black-body radiator was independent of the
power applied to it, an important assumption of the properties of the black-body
radiator that had not been previously observed. The beam emitted from a vibrating
wire was found to be much narrower and has a angular profile that changes as
the velocity of the wire is increased. Probing a turbulent tangle generated by a vibrating wire with this beam showed
that the turbulence appears to fill all of the volume in between the radiator and
detector. The vortex line density of the tangle appeared the be greatest in the
vicinity of the wire, consistent with previous measurements of the vortex tangle
generated by vibrating wires. In addition, we find that there are reproducible features in the development of the
shadow as a function of the wire velocity, indicating that there is some structure
in the development. The shadow is independent of the power of the beam used to
probe the tangle. Measurements of fluctuations in the shadow cast by the vortex tangle show that
the turbulence has a spectrum reminiscent of the Kolmogorov spectrum. In addition
to this the resolution of the detector is such that it is possible in principle to
measure the shadow cast by a single vortex line, and we examine candidate events
for such a measurement. This represents the first such measurement of the motion
of vortex lines in 3He-B.