Electrical ionizing devices for lightning protection

A device for protection against lightning including:

• a lightning rod point (100), the lateral surface (110) of which is a rotation surface inscribed in an enveloping cone (C),
• a conductive rod (210) connected to the potential of the earth and supporting said point, said rod being hollow and housing a central core (220), which core is electrically connected to the point and protected by an insulating sheath (230) of said rod,
• a high-tension source (300) for bringing said point to an elevated potential capable of generating an emission of ions by Corona effect, and a spark-gap device that makes it possible electrically to connect said point to the earth in case the latter is subjected to a thunderbolt or other excessive tension, said spark-gap device including an upper armature formed by the base (120) of said point (100) and a lower armature including a conductive crown (240) connected to said rod (210) and situated opposite the base of said point and spaced therefrom,
• characterized in that said base of said point is lengthened by a flared protective skirt (130) extending downwardly so as to cover at least partially said conductive crown (240), the distance separating the internal surface (131) of said skirt from the lateral surface (241, 242) of said conductive crown remaining always at least equal to the distance between said armatures of said spark gap,
• said insulating sheath (230) is upwardly extended until reaching the base of said point and has, specially on the portion (231) situated at the height of the dielectric interval between said armatures of said spark gap, a narrowing (D) of its diameter so as to increase the distance between the surfaces (232;
• 131, 241) facing said sheath and said armatures of said spark gap,
• the roughness R.sub.a of said internal surface (131) of said skirt is less than 0.2 .mu.m.