Why Mercury?

[Paul Andrews]

Hi,

I've been trying to find information on what the mechanism is that allows Mercury to extend the lifespan of Nixie tubes. I haven't been able to find anything, only assertions that 'Mercury is added to extend the lifespan of the tubes'. I found a link about the halogen cycle on this group. Again the assertion about Mercury was made, but no actual explanation of the mechanism.

Can anyone provide a link or an explanation?

- Paul

[Dekatron42]

Here's one patent: http://google.ch/patents/US3944869 that says:

"For many years, display devices such as NIXIE tubes have used mercury vapor along with the normal inert gas content to minimize cathode sputtering"

There are more patents on the use of Mercury and Nixies that tells the same story, I just dug up this one as I know that Burroughs have some patents in this area. There is more to read in other patents, and I think also in some old Burroughs documents, on the effect of Mercury and sputtering.

/Martin

[Paul Andrews]

OK, but how does it reduce sputtering?

--
You received this message because you are subscribed to a topic in the Google Groups "neonixie-l" group.
To unsubscribe from this topic, visit https://groups.google.com/d/topic/neonixie-l/CBHy0uSgjOA/unsubscribe.
To unsubscribe from this group and all its topics, send an email to neonixie-l+...@googlegroups.com.
To post to this group, send email to neoni...@googlegroups.com.
To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/57a5d5c0-0274-4800-9adc-85ae9c3244fb%40googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

[David Speck MD]

Paul, as it was explained to me a long time ago by a forgotten physics
professor, mercury atoms are big, heavy atoms, much heavier than neon
or argon.

As I understand it, sputtering happens when energetic electrons or ions
knock metallic atoms off the surface of electrodes. If there happens to
be a big heavy mercury atom in close proximity, the newly freed metal
atom may bounce off it, right back onto the electrode surface where it
started. This would slow the rate of metal removal from the electrode.

As I think of it, I wonder if the mercury may bond or amalgamate with
the electrode surface, and become a renewable sacrificial surface layer
for the electrode.

Dave

[NeonJohn]

On 03/08/2017 08:15 AM, Paul Andrews wrote:
> OK, but how does it reduce sputtering?
>

Two mechanisms. First, its ionization potential is lower than neon so
the atoms have less voltage to accelerate them. Second and most
importantly, the mercury ion is MUCH heavier than neon and so
accelerates to a much lower speed across the potential than neon. A
third effect is that the cathodes are coated with a thin film of mercury
so many of the collisions are mercury on mercury.

John


--
John DeArmond
Tellico Plains, Occupied TN
http://www.tnduction.com <-- THE source for induction heaters
http://www.neon-john.com <-- email from here
http://www.johndearmond.com <-- Best damned Blog on the net
PGP key: wwwkeys.pgp.net: BCB68D77