The TWTs generally are radiation cooled. Meaning that the collectors (where
most of the heat is dissipated) have large fins that radiate the heat to
space. Most space TWTs are this way. Some, however, are conduction cooled
to the mounting surface (referred to as the 'panel') and that heat is
dissipated elsewhere, the heat being transferred away from the TWTs with
heat pipes underneath and integral to the panel. All the TWTs, radiation
cooled or conduction cooled, have such heat pipes below them.

"Yves Monmagnon" wrote in message
...
Dreaming ....
I've heard that some Broadcast TV satelites use TWT as power amplifiers.
Do they have a hermetically sealed envelope
As a reference to the LOOOOOOOOOONG thread about plate color and how they
radiate heat in vacuum, does somebody knows how those power TWTs evacuate
heat ?
Wondering ....
Yves.