Method and device for outside plasma deposition of hydroxyl ion-free silica
AssigneeCompagnie Generale d'Electricite
InventorChristian Le Sergent
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Abstract
Method of outside plasma deposition onto a rod (17,22) of silica substantially free from hydroxyl ions, possibly doped to change its refractive index, by reaction with oxygen of a silicon compound and possibly of doping compounds, in the presence of a gas plasma raised to a very high temperature (16) by induction with the help of a high frequency generator (15). The rod on which the silica deposit is made is kept in a sealed chamber (19) separated from the surrounding atmosphere and supplied by a pipe (20) with atmospheric air that is successively passed through a filter (31), a compressor (32) a cooling means (33), a condensation water drain (35) and a final desiccation by adsorption (36, 38). A device for implementing the method is also claimed.
Claims9
A method for plasma deposition of substantially hydroxyl ion-free silica onto the outer surface of a silica rod, comprising the steps of providing a sealed enclosure containing a rod, which sealed enclosure is separated from the surrounding atmosphere, reacting in the sealed chamber a silicon compound with oxygen in the presence of a plasma generated by induction with a high frequency generator to deposit silica onto the rod, wherein said enclosure is supplied with atmospheric air which has successively been subjected to filtering, compression and cooling, draining of condensation water and a final desiccation by adsorption.
A device for plasma deposition of substantially hydroxyl ion-free silica onto the outer surface of a silica rod, by reaction of a silicon compound with oxygen in the presence of a gas plasma generated by induction with a high frequency generator to deposit silica onto the rod, comprising a rod for receiving the silica deposit, a rig imparting rotation and translation to the rod, a torch delivering a plasmagene gas, an induction coil supplied by a high frequency generator around the end of the torch and a nozzle for injection towards the rod a mixture of oxygen and a silicon compound, all of these elements are arranged inside a sealed enclosure separated from the surrounding atmosphere, and wherein said enclosure is supplied with atmospheric air by piping means equipped with at least a filter, a compressor, a cooling medium, a condensation water drain and at least one residual moisture adsorption bed.
Dependencies are inferred from the claim text.