[Amps] Kenotron tubes???

[Borislav Trifonov]

I got some antique kenotron tubes, but from what I can tell they are just high voltage rectifiers. Anyone here old enough to know if there's any difference between other tube rectifiers and kenotrons, or it's just a different name?

They are pretty large, thick HV insulator-style ribbed glass body and labeled General Electric KR-9. They come from an old X-ray machine, but I don't have any ratings on them.  I'd like to figure out the heater voltage and current, and the max the plate can handle (I do intend to use them for an X-ray supply).