A nozzle with an electric arc-blast having a median part of a first dielectric material and two end parts. The nozzle includes an insert of a second dielectric material, chosen from among: a composite material including a fluorocarbon polymer matrix and inorganic filler A chosen from among a sulfur, a ceramic and an oxide (SiO2, TiO2, Al2CoO4, ZnO, BaTiO3 and P2O5), in a percentage weight ranging between 0.1% and 10%, and/or at least one inorganic filler B (a graphite, a mica, a glass and a fluoride), in a percentage weight ranging between 5% and 50%, and a ceramic material including compound(s) (a carbide, a boride and an oxide).