Electric arcing (see Wikipedia:electric_arc) can be damaging and is usually to be avoided in particle optics systems. It can occur, for example, if two conductive electrodes with a high enough potential difference are placed too close together.
In the context of SIMION, you may want to predict whether arcing will occur. Arcing can depend on a variety of different factors such as
- the electric field magnitude relative to the dielectric strength (see Wikipedia:Dielectric_strength)
- the type of medium between the electrodes (could be vacuum or some type of gas, liquid, or solid)
- the pressure (for gaseous mediums)
- the distance between the electrodes (see Wikipedia:Paschen’s_law)
- the electrode surface roughness or shape, and
- any surface contamination.
To provide some context, the dielectric strength of air (not vacuum) is roughly 3E+6 V/m (ref) but of course depends on other conditions.
SIMION can at least tell you about the strength of the electric field (via the Laplace Equation). The Gradient Contour type on the View screen can be helpful in highlighting regions of your system that exceed a certain field strength.
Even in a perfect vacuum, there is a limit to the field, on the order of V/nm, above which Field Emission can occur. Field emission can sometimes be a useful process, such as in the case of field emission cathodes.
- Field Emission
- http://ethesis.nitrkl.ac.in/2875/1/Full_Thesis_Print_04.07.2011.pdf - Measurement of Air Breakdown Voltage and Electric Field Using Standard SPhere Gap Method. Paraselli Sankar. June 2011.
- http://blazelabs.com/l-vacuum.asp - plot of dielectric strength v.s. air pressure.