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Registered Member #1321
Joined: Sat Feb 16 2008, 03:22AM
Location:
Posts: 843
The spark gap has to be designed with the whole system in mind.
What are the design goals of the system? Start with the load. Try to determine what the load looks like, electrically, and decide how much power you want to put into it. Then work your way backward from there.
Maybe you don't actually need what you think you need. Maybe there are other approaches to get what you want.
I need 5 ns pulse width with less than 800ps rise time. 10kv 10khz rep rate.
So what decomposes with heat that could be used to release h2 gas? do you think that taking apart a NI-MH battery and filling it with h gas and having a small nichrome heater might work?
Registered Member #2893
Joined: Tue Jun 01 2010, 09:25PM
Location: Cali-forn. i. a.
Posts: 2242
Here's my idea.
Basically you just shake the thing and the zinc an hcl react, that makes hydrogen. The cotton balls keep the liquid out of the spark gap, but let the gas through.
Registered Member #1321
Joined: Sat Feb 16 2008, 03:22AM
Location:
Posts: 843
Ok, but how do you know you need 5 nS pulses rather than 10 nS for example? And how did you determine that you need 800 pS rise time rather than say 1 nS rise time?
And what does the load look like electrically? Is there a lot of stray capacitance to ground that you have to drive? What kind of power throughput do you expect?
Sorry but I don't know anything about "lifters", so these are the kinds of things I would want to know way before I even started thinking about the details of spark gap design.
The first thing I would generally do is research the characteristics of the load, then maybe try to model it with a spice program or something...just to get an idea of what you're dealing with. (BTW the spice program "Microcap" includes with a fairly sophisticated macro that simulates a spark gap).
Here's a paper describing a HV pulser meant to drive a "pulsed corona discharge". Would this be something physically similar to what you want to do?
Edit:
Another thought: Maybe you could look into something called a "dielectric barrier discharge" (DBD)...aka a "silent discharge". IIRC, these types of discharges can be designed to deposit lots of power into a gas discharge (I think at atmospheric pressure)without degenerating into an arc. I think I recall reading about some high pressure gas lasers (e.g. CO2 TEA lasers) and some high pressure excimer lamps, being driven this way. Some use high frequency AC while others use a short pulse.
Then there's another method whereby the electric field in the air (or other gas) is of high and constant magnitude, but doesn't cause an arc because the field is made to rotating rapidly in space (not mechanically, but by proper phasing of the HF AC drive signals).
(I'm really not familiar with how lifters work, so I don't know if any of these ideas would have any relevancy to what you're trying to do).
Registered Member #3282
Joined: Wed Oct 06 2010, 05:01PM
Location:
Posts: 224
the high voltage must terminate before the leader streamer makes its way into the gaseous medium. I read in some journals that a short enough discharge can result into a steady corona condition where 10kv can be put at 2mm distance in air and not spark. can't find the source but i have some really cool inventions that could use this effect.
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pressurized hydrogen spark gap
