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by dr_orpheus
1029 days ago
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> I'm surprised about is that there hasn't been much discussion about their componentry and why they've been so reliable I think part of this might be because it is still considered proprietary information. Kind of crazy, but there is really only one company in the US that makes space qualified TWTs which is Stellant systems (formerly L3, formerly Hughes microwave) who made the Voyager TWTs as well. |
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You're likely right about the proprietary nature of such manufacturing but perhaps I'm reading too much into this. As I mentioned in an earlier post the emission in the CRT of my 43-year-old Sharp TV is still OK—at least as far as the quality of the image is concerned.
The technology used in the Wehnelt cylinder in my TV's CRT is of a similar vintage to Voyager (I'm pretty sure the TV was manufactured around 1979), and given the millions of CRTs made to similar a quality around that time it's likely that manufacturering techniques and reliability figures were widely known throughout the industry by then.
Anecdotally, I've noticed that CRTs made from the early '70s onwards had much better longevities than their earlier '50s counterparts, whether this was because the formulation of cathode emitters had changed or manufacturing techniques had improved or both is an open question.
Of course, such comparisons are tenuous but that's all I've got to go on, for starters, the Wehnelt in the Voyager's TWT would have been deigned to carry more current. Perhaps NASA has some spare TWTs that one day someone will reverse engineer and we'll know for sure.
Nevertheless, it seems to me that knowledge about component reliability is critical to NASA, so it's likely the answer already exists somewhere in the depths of NASA's archives.