In message .com,
Matty F writes
Colin Wilson wrote:

I'm crap at electronics, but I remember a "cockroft walton ladder" being
used in several ioniser designs

This one is a bit big for the average room. I'm working on a smaller
one right now:
http://i17.tinypic.com/2r39l06.jpg

But if you want serious ...

http://www.lod.org/

(having just read a 6 month old New Scientist)

--
geoff