The outer larger diameter ones are the Cu/W mix, middle one is Tungsten
(with a trace element - TIG rods)
Regards Phil www.hvtesla.com
On 19/08/17 20:34, Carl Noggle wrote:
You can get copper-tungsten alloy which is about as robust as tungsten
but machines like free-machining brass. Mine is 85% W, 15% Cu. I
have been using a set of annular blown gaps for about twenty years on
my 2 kW coil. You have to polish them up with fine sandpaper every
few years, but they show no appreciable wear after all those coulombs
have passed through them. They aren't really an alloy, more like W
particles in a Cu matrix. A Google search will turn up several
manufacturers and a good Wikipedia article.
The electrodes are made with Cu-W faces pressed onto brass tubes. They
are screwed into large aluminum discs for heat dissipation, and with a
vacuum cleaner motor running at 48 VAC, they run quite cool.