Need some advice on multiplexing high voltages in the range of 2KV to 12KV ( with a small current like 10mA to 80mA).
What I mean : is there any electronic component capable of that (i.e. thyristors, transistors, special IC, etc) switching in the High Voltage side, without using any transformers.
That voltage levels are quite high. If you looking for a semiconductor device that can switch to those voltage level, I am afraid you won't find any. Normally electrons in the semiconductors at this tremendous pressurel will be force to move causing permanent damage and permanent short to the terminals of the semiconductor device. My suggestion is use a electyro mechanical device, probably relay of some kind or pneumatic devices that will break through the connection physically. This is a normal practice in high voltage control such as power lines and high capacity generators. They use pneumatic switches.
Here's one company that makes small HV relays. Beware - expensive!
**broken link removed**
The web site also has a cross-reference to other manufacturers.
The device will have to operate 24/7 with switching times ~ 100us to 800us. That's why have written "quite fast" with respect to using hv relays. So unless I 'll find some relay switching at that speed (though I'll have to replace them often if do) I will use multiple hv transformers and do the multiplex in primary low voltage winding. It's about a big neon signboard to be more specific.