Phil,
My only suggestion would be possible oxidation. I had noticed a white to yellowish-brown powdery residue form on (and around) the RSG components after so much run time. Back then, in my early days of big coiling, I was running solid brass electrodes and of course, they were eroding at a fairly good clip. My electrodes now are all pure tungsten, though, and this problem seems to be considerably less prevalent since going to pure tungsten. Maybe the copper tungsten alloy is eroding/burning more and causing more residue than pure tungsten? Otherwise, I'm lost, too.
David
On Thursday, March 12, 2015 5:30 PM, Phil <pip@xxxxxxxxxxx> wrote:
Gents,
The electrodes of my RSG had quite an odd appearance when viewed up close,
after running at a recent teslathon, obviously not really mould, but I have
never seen this occur before:
https://www.flickr.com/photos/33962508@N03/16794887172/in/photostream/lightb
ox/
(click to enlarge)
Ablation was only around 10 thou or so, and the ridges that you see are
mainly formed by deposits. The outer two are the stationary pair (3/8 inch
Tungsten/copper alloy), while the centre one, is one of the four rotating
ones (0.25 inch thoriated tungsten).The other three looked the same. Power
was around 7.5 kw
Phil
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