[3dem] [External] Re: glow discharge "fireball"

[Garrett, Aria E]

We have had issues with the ‘fireball’ and our solution was to use a block grid holder made from plastic instead. Eventually we got it fixed/replaced - not sure on the details.

Best,
Aria

From: 3dem <3dem-bounces at ncmir.ucsd.edu> on behalf of CF David Hou via 3dem <3dem at ncmir.ucsd.edu>
Date: Wednesday, February 4, 2026 at 4:40 PM
To: Jason Kaelber <jason.kaelber at rutgers.edu>
Cc: 3dem at ncmir.ucsd.edu <3dem at ncmir.ucsd.edu>
Subject: [External] Re: [3dem] glow discharge "fireball"

Dear Jason,

Just a quick thought. Place a sheet of parafilm between the platform and the block may help.

Though I don’t know why. People here just replace a new glow discharger.

Best,

David

On Wed, Feb 4, 2026 at 16:20 Jason Kaelber via 3dem <3dem at ncmir.ucsd.edu<mailto:3dem at ncmir.ucsd.edu>> wrote:
Dear 3DEM,
When glow discharging with our Pelco easiGlow (e.g. at 15 mA, 0.39 mBar room air for 25 seconds) on the aircraft aluminum grid blocks, sometimes a ball of plasma will be observed above one grid, or one ball each among several randomly-placed grids in the block. The ball is light pink and may manifest at any time during the discharge, typically enduring until the end of the cycle but perhaps flickering in and out of existence. Below I enclose a photograph of the phenomenon:
[cid:ii_19c2a96165053fdc8b11]
Have any of you observed this? Do you know the cause or solution? It doesn't happen when we glow discharge on glass slides—but on the other hand, we we using the aluminum blocks for a couple years without issue before ever seeing this, and ordering a brand-new block doesn't help.

Thank you in advance for your helpful replies,
Jason Kaelber

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