Estoy aqui.
This topic requires more research than I can do during a work week. What I have been mevarer so far is that the filaments you refer to are the same ones used as the starter, in order to get the electricity to flow through gas. And not all hot cathodes are the same, and not all thermionic emissions are the same.In the interim I will trust my rav on this. That said, I have asked a frum friend who is on break from his doctorate and loves to tinker with a soldering gun and circuits to be mevarer the metzius for me. I will iy”h have more time over the weekend to do more reading on the topic. I will also report what my friend says. I have asked him to examine a cfl because those are the bulbs used today, until LED bulbs become practical.