Patent ID: 8907552

Claim:
A high-frequency plasma ignition plug comprising: a center electrode extending in a direction of an axis; an insulator having an axial hole into which the center electrode is inserted; a tip joined to a forward end portion of the center electrode by a fusion portion which is a formed through fusion of the tip and the center electrode; a tubular metallic shell provided around the insulator; and a ground electrode fixed to a forward end portion of the metallic shell and forming a gap in cooperation with the tip, the ignition plug being adapted to generate high-frequency plasma at the gap when high-frequency electric power is supplied to the gap, and being characterized in that a forward end of the tip is located forward of a forward end of the insulator with respect to the direction of the axis; at least a portion of an outer surface of the fusion portion is located within the axial hole; and a distance between a forward-end-side opening of the axial hole and a rearmost end of the outer surface of the fusion portion, measured along the axis, is equal to or greater than 0.1 mm.