Campbell Scientific CS110 Electric Field Meter User Manual
Page 20
CS110 Electric Field Meter
minimize non-ideal fringing effects. Sharp corners were avoided in order to
prevent corona discharge. All metal parts of the calibrator are manufactured
from stainless steel, and the inside surfaces are polished to reduce the surface
charges in order to provide a stable zero electric field. All outer surfaces are
electrically connected and tied to Earth ground while the insulated inner plate
is driven by a high voltage amplifier. The high-voltage amplifier is calibrated
out-of-house yearly against a reference that is traceable to the National Institute
of Standards and Technology (NIST).
FIGURE 5. Parallel-plate electric field meter calibration chamber
Each CS110 is factory calibrated in the parallel plate calibration fixture
depicted in Figure 5. A linear fit of the calibration data results in a calibration
equation in slope-intercept form expressed as
E
=
M
parallel_plate
⋅V + O
parallel_plate
(eq.
3).
The multiplier M
parallel_plate
is a function of the CS110 electrode dimensions and
the feedback capacitor in the charge amplifier. The offset term O
parallel_plate
is
due to unwanted surface charges residing on non-conductive deposits on the
electrodes. The electric field offset of an instrument varies over time because
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