It still dropped out with the current set at 7mA. After a while a buzzing sound develops which becomes increasingly low frequency until the plasma is lost, and sometimes it will then strike back up again. Not sure why it's dropped out unless some component is heating up and causing failure -- perhaps related to the voltage being down also.

Cheers,

Andrew

On Thursday, 6 March 2014 17:54:55 UTC, Andrew Back wrote:
Hi Sam,



On Wednesday, 5 March 2014 21:16:34 UTC, Samuel M. Goldwasser wrote:



The tube probably IS at least one of the problems assuming no one has



messed with the mirror alignment.



Ah, so I'll look into sourcing a bottle of helium.



There's a range of current that would be OK. I'd suggest increasing it



to 7 mA. That should stop it from dropping out. I don't think there



is anything wrong electrically but the tube has leaked. If you can run



it for a few hours or days, it may recover at least partially.



I've turned the current up to 7mA and will see how it gets on. Any idea why the voltage is only ~2.7kV and what I could try to get the exciter output back up to 3.7kV?



Looking into the end of the tube the optics do look grubby, but I get the impression that attempting to clean them may not be helpful.



Thanks for the advice, it's much appreciated!



Regards,



Andrew