29 Sep
2012
29 Sep
'12
12:30 p.m.
On Fri, 28 Sep 2012, Dave McGuire wrote:
> On 09/28/2012 01:29 PM, Alexey Toptygin wrote:
>> On Thu, 27 Sep 2012, Tony Duell wrote:
>>
>>> No. AFAIK _no_ green displays are nixie tubes (what gas would they have
>>> to contain I wonder?)
>>
>> Oxygen at a suitable pressure? IIUC at very low pressure it glows red,
>> at higher pressure it glows green and at suffieciently high pressure the
Are you sure that oxygen can be got to give a gree nglow? I asked my
father about this, who has done a _lot_ of work on vacuum systems, and he
claimed it doesn;t. The (foten green) glow you see at very low pressures
is in fac the glass fluorescing.
decay is non-radiative. I'm guessing you'd
have problems with electrode
erosion though.
Uhh...ya think? ;) I'd bet the electrode life would be measured in
single- or two-digit MINUTES depending on their thickness. different, you're not discharging through the gas,
and the lower pressure
That is quite big differnece. Having an ionised plasma is very differnt
from having a gas.
will make the tungsten evaporate faster, but I
imagine/hope it would at
least last hours or days. Alternatively, you could try to build a barrier
that's impermeable to oxygen but permeable to high energy electrons. But
I'm probably overthinking it. Surely there is another element that will
emit mostly in the green part of the spectrum?
Well, I am sure there are metalic vapours that do (barium?) but of course
such lamps normall start with some other gas (neon, argon) and the heat
from that discharge vaporisses the metal. Think of the
sodium street
lapmps. They start off growing red -- that's neon.. You get the
yellow
sodium light only after the metal has vaporised. I don;t think,
therefore, that a metal vapour would be suitable for a nixie tube.
S am sdubious about Ne/Kr mixtures. I can find no refernece to these
giving a green glow, does somebody have a reliable reference for this?
Ofte nKr87 was added to the enon gass in gass discharge displays, it's
mildly radioactive and helps ionisation of the neon. And such displays
glow orannge. Of course the compostiion may well make a difference to the
colour, but I am tryign to think of a physcial mechanism to get green
ligth from said mixture...
-tony