US 11,956,884 B2
Plasma chemical vapor deposition apparatus
Igor Milicevic, Helmond (NL); Mattheus Jacobus Nicolaas Van Stralen, Tilburg (NL); Gertjan Krabshuis, Sint Oedenrode (NL); and Antonius Henricus Elisabeth Breuls, Urmond (NL)
Assigned to Draka Comteq B.V., Delft (NL)
Filed by Draka Comteq B.V., Delft (NL)
Filed on May 18, 2022, as Appl. No. 17/747,068.
Claims priority of application No. 2028245 (NL), filed on May 19, 2021.
Prior Publication US 2022/0377871 A1, Nov. 24, 2022
Int. Cl. H05H 1/46 (2006.01); C23C 16/40 (2006.01); C23C 16/511 (2006.01)
CPC H05H 1/461 (2021.05) [C23C 16/402 (2013.01); C23C 16/511 (2013.01); H05H 2245/42 (2021.05)] 17 Claims
OG exemplary drawing
 
1. A plasma chemical vapor deposition apparatus for deposition of one or more layers of silica onto an interior wall of an elongated hollow glass substrate tube, the apparatus comprising:
a microwave generator;
a plasma generator receiving microwaves from the microwave generator in use;
a cylindrical cavity extending through the plasma generator; and
a cylindrical liner that is transparent to microwave radiation and that is positioned in the cavity, a central axis of the liner being coaxial with a central axis of the cavity, wherein the substrate tube passes through the liner in use, wherein, over a part of the length of the liner, the liner has at least one section having a reduced inner diameter with respect to an inner diameter of a remaining part of the liner, said at least one section having a reduced inner diameter providing a contact zone for the substrate tube;
wherein the microwave generator is configured to generate microwaves having a wavelength Lw in the range of 40 millimeters to 400 millimeters; and
wherein said at least one section having the reduced inner diameter has a length of at least 1 millimeter and at most 0.1×Lw.