[3dem] glow discharge "fireball"

[Jason Kaelber]

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:d33a233b-ab8e-4ca5-984e-cf9e704962bc]
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

--
J T Kaelber, PhD
Director, Rutgers CryoEM & Nanoimaging Facility<https://urldefense.com/v3/__https://iqb.rutgers.edu/rcnf__;!!Mih3wA!BIMk5_e1YisTp15tE62Tm9GjzuMp9oIisvDNDFnWqD4hL0hxj6BG22PIxpNMKjd0GwSy7ahGu05ofPVEsuxIfUGqqGFBWg$ >
Institute for Quantitative Biomedicine
174 Frelinghuysen Rd
Piscataway, NJ 08854
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