I'm investigating characteristics of Pt spark plugs for use in a gas contamination detector.(Not gasoline)
Our current instrument uses a continuous arc drawn between chisel tip tungsten electrodes powered by a 1KV DC power supply.A spectral peak of the arc varies with the degree of contamination (N2 in He). The light is focused on a scanning monochrometer tuned to the relevant wavelength.
The stability of the arc is critical to accurate measurements. The large size of the electrode chisel tip(~4mm) allows the arc to "wander" out of ideal optical calibration, especially if physical/chemical contaminants are introduced into the arc chamber. Mechanical shock will also upset alignment. Machining and parts cost play a factor in our desire to replace this design.
Questions are:
1. In an auto,is the applied V at the plug center electrode + or -, relative to the grounding electrode?
2. How does our continuous I of 11mA compare to the arc current of normal automotive applications?
3. Power rating of internal R in resistor type plugs?Are Pts available w/o R?
The physics of arc propagation are not completeley understood, and we are concerned about erosion/deposition on the plug electrodes.
With its small cross sectional area, a flush trimmed center electrode would seem to offer the more
precise and stable arc point.
Our current instrument uses a continuous arc drawn between chisel tip tungsten electrodes powered by a 1KV DC power supply.A spectral peak of the arc varies with the degree of contamination (N2 in He). The light is focused on a scanning monochrometer tuned to the relevant wavelength.
The stability of the arc is critical to accurate measurements. The large size of the electrode chisel tip(~4mm) allows the arc to "wander" out of ideal optical calibration, especially if physical/chemical contaminants are introduced into the arc chamber. Mechanical shock will also upset alignment. Machining and parts cost play a factor in our desire to replace this design.
Questions are:
1. In an auto,is the applied V at the plug center electrode + or -, relative to the grounding electrode?
2. How does our continuous I of 11mA compare to the arc current of normal automotive applications?
3. Power rating of internal R in resistor type plugs?Are Pts available w/o R?
The physics of arc propagation are not completeley understood, and we are concerned about erosion/deposition on the plug electrodes.
With its small cross sectional area, a flush trimmed center electrode would seem to offer the more
precise and stable arc point.