Decreasing gas breakdown distance in a spark gap with UV

  • #1
1
0
Hello !
I am currently investigating a technique that would allow several spark gaps to breakdown synchronously in an enclosed but not hermetical cavity, flushed with N2 at 1atm and ~25°C

My idea was to use "indirect" photoionization (basically a synthetic fused quartz UV flash discharge inside the cavity)
The cavity would be enclosed with a highly reflective material to UV from 160nm to the near UV.
However, ionization of the outer electron shell of N2 seems to be at ~15eV, and at 160nm we are nowhere close to this photon energy level.

So, i was wondering if any indirect effect (N2 excitation, thermal effects ?) would eventually "help" to lower the dielectric strength with that method. Keep in mind that the flash lamp would send a burst of 100 to 200 J of light...

Or is it a dead end ? I could always ionize the surroundings with a spark gap trigger not enclosed in a flash lamp, but it is a bit too dirty (because of the "brutal" thermal/accoustic shockwave influence on the secondary spark gaps)

Anyone could shed a bit of light on this issue ? ;) - i would rather not change the dielectric gas because i am afraid of unintended consequences (ozone generation for O2, fire hazards, etc)
Thx.
 

Answers and Replies

  • #2
tech99
Gold Member
1,929
693
Hello !
I am currently investigating a technique that would allow several spark gaps to breakdown synchronously in an enclosed but not hermetical cavity, flushed with N2 at 1atm and ~25°C

My idea was to use "indirect" photoionization (basically a synthetic fused quartz UV flash discharge inside the cavity)
The cavity would be enclosed with a highly reflective material to UV from 160nm to the near UV.
However, ionization of the outer electron shell of N2 seems to be at ~15eV, and at 160nm we are nowhere close to this photon energy level.

So, i was wondering if any indirect effect (N2 excitation, thermal effects ?) would eventually "help" to lower the dielectric strength with that method. Keep in mind that the flash lamp would send a burst of 100 to 200 J of light...

Or is it a dead end ? I could always ionize the surroundings with a spark gap trigger not enclosed in a flash lamp, but it is a bit too dirty (because of the "brutal" thermal/accoustic shockwave influence on the secondary spark gaps)

Anyone could shed a bit of light on this issue ? ;) - i would rather not change the dielectric gas because i am afraid of unintended consequences (ozone generation for O2, fire hazards, etc)
Thx.
I think you will find they trigger randomly due to background radiation. If you intend them to be truly synchronous, bear in mind that a spark gap can fire in picoseconds. Can you just trigger them with an addition voltage pulse?
When Hertz was experimenting with spark gaps as his radio transmitter, he found the UV from one spark triggered another.
 

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