Quadrupole in CRT - what's its purpose and how does it work?

[gmayer]

Hi there,
I'm working on an oscilloscope from around the late 70s/early 80s with a Thomson CRT inside. This CRT uses quadrupoles which I've never heard of before. I understand that they are a part of the electron optics, but I couldn't find anything about how they work and affect the beam/deflection compared to a non-quadrupole tube. I can fix the scope without understanding that, but I'm just interested... Any information/hint is welcome :-) .
Cheers, Max

[Njk]

First google hit:

Using magnetic quadrupoles in cathode‐ray tubes https://www.tandfonline.com/doi/pdf/10.1080/15980316.2002.9651898

[gmayer]

Thanks! That's a good starting point even thought it's probably not magnetic in my case.

P. S.
I swear I did some research before posting this. I can't believe I missed that!

[David Hess]

Tektronix published general details about quadrupole lenses:

https://w140.com/tekwiki/images/0/0f/Tek_forum_report_5.pdf