Optical studies of the pre-breakdown mechanism in dielectronic liquids.
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The work described in this thesis provides an
optical study of pre-breakdown events in liquid
dielectrics. A small scale rig employing a 50SI test cell
with viewing windows, as part of a high voltage co-axial
line, enabled short rise time pulses to be applied to a
non-uniform test gap. For the liquid dielectric, changes
of refractive index resulting from applied voltage were
rendered visible by means of a Schlieren optical system.
A high speed image converter camera enabled rapidly
changing pre-breakdown phenomena to be photographically
recorded at framing speeds up to 107 per second. Scattered
light photographs were taken by orthogonal flash
illumination under both pulse and direct voltage conditions,
allowing large format macrophotography. Using a piezoelectric
transducer placed within the test cell, and a
photomultiplier to view the gap region, a relationship has
also been established between the generation of mechanical
waves, light scintillation and conduction current pulses.
From the photographic records and conventional
parameter measurements there exists strong evidence for the
presence of a gaseous phase in processes leading to the
electrical breakdown of liquid dielectrics even under pulse
conditions.
Authors
McGrath, P. B.Collections
- Theses [3834]