Plasma ignition and cooling apparatus and methods for plasma systems are described. An apparatus can include a vessel and at least one ignition electrode adjacent to the vessel. A total length of a dimension of the at least one ignition electrode is greater than 10% of a length of the vessel's channel. The apparatus can include a dielectric toroidal vessel, a heat sink having multiple segments urged toward the vessel by a spring-loaded mechanism, and a thermal interface between the vessel and the heat sink. A method can include providing a gas having a flow rate and a pressure and directing a portion of the flow rate of the gas into a vessel channel. The gas is ignited in the channel while the remaining portion of the flow rate is directed away from the channel.