Decreasing gas breakdown distance in a spark gap with UV

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SUMMARY

This discussion focuses on the technique of achieving synchronous breakdown of multiple spark gaps within a non-hermetical cavity filled with nitrogen (N2) at 1 atm and approximately 25°C. The proposed method involves using indirect photoionization via a synthetic fused quartz UV flash discharge, although the ionization energy for N2 is around 15 eV, which is not achievable with 160 nm UV light. Participants suggest that background radiation may cause random triggering of spark gaps and recommend considering additional voltage pulses for reliable synchronization.

PREREQUISITES
  • Understanding of spark gap technology and its applications
  • Knowledge of photoionization principles and energy levels
  • Familiarity with nitrogen gas properties and its behavior under electrical discharge
  • Experience with UV light sources and their spectral characteristics
NEXT STEPS
  • Research the principles of indirect photoionization and its applications in electrical engineering
  • Investigate the effects of background radiation on spark gap triggering
  • Explore methods for generating additional voltage pulses to synchronize spark gaps
  • Study the thermal and acoustic effects of spark gaps on surrounding components
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Electrical engineers, researchers in plasma physics, and professionals working with high-voltage systems who are interested in spark gap synchronization techniques and photoionization methods.

rodv92
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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.
 
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rodv92 said:
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.