*…you will see that spark length is heavily dependent on the gas composition and pressure. Higher pressure means shorter spark at same voltage, you won't get a 12mm spark in high pressure H2*
This is a good observation. The situation gets more complicated when dust is suspended in the gas. The dust will also slow down and deenergize the electrons as the electrons collide with the gas and the dust. Such collisions reduce the electron's energy making it more difficult for these electrons to ionize a molecule. Energy losses from a greater number of collisions require larger voltages for the electrons to accumulate sufficient energy to ionize all of the hydrogen atoms required to produce a plasma channel caused by an avalanche breakdown. Ions streaming past a dust particle exert a force on the dust by scattering of the ions in the electric field of the dust or by collection on the dust surface. In plasma discharge there always is a persistent ion stream either due to ambipolar diffusion in the plasma bulk or due to the electric fields in the plasma sheath. This ion drag force is one of the major forces on dust particles. It is understood qualitatively, but a complete quantitative description is still missing due to the complexity of the involved processes. The ions which arrive at the particle not only contribute to ion charging of the dust, but also transfer their momentum to the dust and thus exert the collection force on the dust. The bottom line: You can’t have enough voltage. Cheers: Axil On Wed, May 30, 2012 at 3:00 PM, Robert Lynn <robert.gulliver.l...@gmail.com > wrote: > Check out he pashen discharge curves: > http://en.wikipedia.org/wiki/File:Paschen_Curves.PNG > and you will see that spark length is heavily dependent on the gas > composition and pressure. higher pressure means shorter spark at same > voltage, you won't get a 12mm spark in high pressure H2 > > Discharging through 2 spark plugs in parallel will not work either as the > resistance drops massively as soon as a plasma channel forms diverting all > current to one spark plug or other but not both. Connecting the sparkplugs > in series might work but the driving circuit won't handle it as the reactor > will need to be at a voltage half way between the two outputs from the > sparking circuit. Unless you have a lot of additional complications with > high voltage isolation capable floating power supplies. However powering > the circuit with a well insulated battery might work. > > > On 30 May 2012 19:25, ecat builder <ecatbuil...@gmail.com> wrote: > >> A quick followup on spark plugs.. I think I found what I was looking >> for.. A small, cheap, and simple spark gap igniter that takes 5V and >> produces 1/2" sparks. Less than $20 shipped. >> >> http://www.sparkfun.com/products/11218 >> >> Skip to 10:45 on the video to see it working. >> Would be strong enough to drive two spark plugs.. >> >> Thoughts? >> - Brad >> >> >
