THESIS

[matches/honours.git] / thesis / appendices / appendixA.tex

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@@ -97,11 +97,7 @@ Ideally, the electron gun should produce a constant emission current for fixed e
 
 A measurement point was included for the total leak current through most of the gun electrodes. 
 
-\subsection{The Ammeters}
 
-An ideal ammeter has no input resistance. In reality, it is not the current that is measured, but the voltage accross a fixed input resistor. This voltage can either be amplified, or the resistance increased, for measuring a smaller current.
-
-The 602 and 610B electrometers both provide a large range of scales and amplifier settings for current measurement. Using a low scale setting increases the input impedance, which increases the potential drop accross the ammeter. However, using a large amplifier gain increases noise; hence there is a trade off. For the 602 and 610B electrometers, a significant drift (typical +5\% of scale in 10min) in the zero level was also observed at high amplifier gains, whilst low gains appeared more stable (+10\% noted after 2 days).
 
 \section{Data Aquisition and Automation}