Spark gap

A spark gap consists of two metal electrodes placed close to each other with a gap in between, where an electrical spark can jump. They are used for igniting the fuel in combustion and hybrid cannons. Spark gaps are normally made by screwing two bolts through the side wall of the chamber, at an angle that puts the tips of the screws close together. The screws should be mounted to keep the heads a good distance apart, to ensure that the spark will not jump between the heads outside the chamber. The distance must be small enough that the voltage from the ignition source can jump across it. The distance is about 1.1 mm/kV, this varies with the shape of the electrodes though, sharp points allow longer sparks than flat surfaces. It should be noted that the pressurized mixture of a hybrid will shorten the max spark length, so a hybrid spark gap should be a fair bit smaller than max spark length to ensure reliability. Spark plugs can be used for spark gaps, and are especially useful in metal guns, where the chamber wall would short out the screws of an ordinary spark gap. Two or more spark gaps can be connected in series to generate multiple sparks, as long as the width of the combined gaps is smaller than the maximum spark distance. Spark gaps can not be wired in parallel, since the spark will then only jump the smallest gap. Spark strips are a popular method of achieving multiple spark gaps.