# Neon lamp: minimal breakdown voltage

I am looking at this formula from wiki for breakdown voltage in gas discharge lamps, and I see its linear by length (d) (oops, I see it's divided by $ln$)

$$\frac{Bpd}{\mathrm{ln}\ Apd-\mathrm{ln}\ (1+\frac{1}{\gamma_\text{se}})}$$

Does that mean that I can make tiny neon lamp with just 0.1 to 0.05mm spacing between electrodes and it will glow as low as 5V for example?

Are there any gases which have lower minimal breakdown voltage than neon?

I guess using niddles instead of parallel plates would also lower breakdown voltage, as field is stronger?

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Not at all! If there are no other paths than those of .1 mm, the lamp will not ignite at all, even not at the usual 70 to 140 Volts depending on elektrode material. – Georg Nov 1 '11 at 23:44
@Georg I don't get it... You mean whole spacing will be in 'dark' area? I had an impression that as you narrow distance between electrodes, electric field increases and accelerates electrons faster... – BarsMonster Nov 2 '11 at 8:43
Look for mechanism of glow discharge, without enough distance to develop a cathode drop, a discharge will not start. Have You ever seen those "candle flicker" glow lamps? The electrodes in that lamps have a distance of about one mm, nevertheless there is no discharge beween them. conrad.de/ce/de/product/550763/FLACKERKERZE-KLAR-230V-3W-E14 – Georg Nov 2 '11 at 9:55

As $A$, $B$ and $\gamma_{se}$ are parameters that do not depend on the distance of the electrodes try to visualize $V=V(d)$ (all in arbitrary units):