How are the beams of electrons in
a TV tube or an oscilloscope generated? Investigate the emission of electrons
from a wire filament as a function of filament temperature and applied electric
field; verify the Richardson-Dushman theory of emission in the current-limited
region of operation and Child's law in the space charge-limited region.
The picture on the left shows an earlier version of this
experiment when a vacuum tube instead of a vacuum chamber was used.
The design of the new vacuum diode is very similar to the original one
shown here.
The glowing filament of the vacuum diode can be
be seen in the picture above.
An ion pump is used to maintain the
vacuum. Additionally, a sorption pump is also connected to the
chamber for the initial "pump-down" in case the chamber has been
opened.
