In the book "Tube: The Invention of Television" the author wrote that early tubes which Zworykin witnessed at a contemporary lab in France had tubes that were pumped down to a very high vacuum whilst working in the lab.
I would assume that these tubes were cold pumped as it has been described that they continued to pump the tubes at the time to maintain the high vacuum.
If the gettering was sufficient, and any metal inside the tube heated, one would imagine that any outgassing would be controlled.
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