If
many identical neon tubes are to be pumped, and if they fit
into an oven (straight tubes are ideal here) then the oven
pumping system is most suitable. One run with some 20 tubes
can take 60 minutes, including the time to connect the tubes.
That is 3 minutes per tube, hence in continuous production
480 tubes per 24 hours. Every time all tubes in the oven are
filled with the same gas at the same filling pressure. Therefore
it is necessary that all neontubes have similar characteristics.
It is very understandable that series of cold cathode tubes
are ideal to be pumped with an automatic oven pumping system.
Two advantages of the oven pumping method are that tubes can
be annealed prior to pumping down, and that vacuum pumping
at high temperature can go on for about an hour, resulting
in a very good vacuum, as the pumping down time is an extremely
important quality factor. |
