Apparatus for indirect atmospheric pressure plasma processing

An apparatus for plasma processing of a continuous fiber, the apparatus comprising:

• a first plasma torch and a second plasma torch, wherein each of the first plasma torch and the second plasma torch comprises:
• a first electrode and a second electrode, wherein the first electrode and the second electrode are spaced apart and are concentric on an axis, the first electrode being disposed within the second electrode, and
• a plasma discharge chamber between the respective first and second electrodes, wherein the plasma discharge chamber comprises an inlet and an outlet for passing a plasma forming gas between the first and second electrodes,
• wherein the first electrode comprises an internal lumen extending to the outlet of the plasma discharge chamber and configured to allow a stream of precursors to be supplied through the internal lumen and injected directly in an afterglow zone;
• an afterglow chamber including the afterglow zone, wherein the afterglow chamber is in fluid communication with the outlets of the plasma discharge chambers of the first and second plasma torches and comprises a substrate inlet and a substrate outlet;
• and
• a transport system configured for continuous transport of the continuous fiber from the substrate inlet to the substrate outlet along a transport direction through the afterglow chamber such that the continuous fiber is kept remote from the plasma discharge chambers while being processed by plasma activated species flowing from the outlets of the plasma discharge chambers into the afterglow chamber;
• wherein the substrate inlet of the afterglow chamber comprises an inlet aperture formed in an upstream wall of the afterglow chamber, and the outlets of the plasma discharge chambers of the first plasma torch and the second plasma torch are arranged opposite one another at an upstream end of the afterglow chamber with the afterglow chamber interposed between the outlets;
• wherein the outlets of the plasma discharge chambers of the first and second plasma torches are interposed between the substrate inlet and the substrate outlet;
• wherein the inlet aperture has a cross-sectional size substantially smaller than a cross-sectional size of the afterglow chamber at the outlet of the plasma discharge chamber of the first plasma torch;
• wherein the afterglow chamber extends from the upstream wall only in a downstream direction with respect to the transport direction of the continuous fiber;
• wherein the upstream wall of the afterglow chamber partially defines the outlets of each of the plasma discharge chambers, and wherein the upstream wall comprises part of a shielding member configured to reduce air entrainment into the afterglow chamber by the continuous fiber;
• and
• wherein the shielding member defines a shielding wall which extends between the outlets of the plasma discharge chambers and the substrate inlet and is aligned with a wall of the outlets.

An apparatus for plasma processing of a continuous fiber, the apparatus comprising:

• a first plasma torch and a second plasma torch, wherein each of the first plasma torch and the second plasma torch comprises:
• a first electrode and a second electrode, wherein the first electrode and the second electrode are spaced apart and are concentric on an axis, the first electrode being disposed within the second electrode, and
• a plasma discharge chamber between the respective first and second electrodes, wherein the plasma discharge chamber comprises an inlet and an outlet for passing a plasma forming gas between the first and second electrodes,
• wherein the first electrode comprises an internal lumen extending to the outlet of the plasma discharge chamber and configured to allow a stream of precursors to be supplied through the internal lumen and injected directly in an afterglow zone;
• an afterglow chamber including the afterglow zone, wherein the afterglow chamber is in fluid communication with the outlets of the plasma discharge chambers of the first and second plasma torches and comprises a substrate inlet and a substrate outlet;
• and
• a transport system configured for continuous transport of the continuous fiber from the substrate inlet to the substrate outlet through the afterglow chamber such that the continuous fiber is kept remote from the plasma discharge chambers while being processed by plasma activated species flowing from the outlets of the plasma discharge chambers into the afterglow chamber;
• wherein the outlets of the plasma discharge chambers of the first plasma torch and the second plasma torch are interposed between the substrate inlet and the substrate outlet and are arranged opposite one another, with the afterglow chamber interposed between the outlets of the plasma discharge chambers of the first and second plasma torches;
• wherein the substrate inlet comprises an inlet aperture having a cross-sectional size substantially smaller than a cross-sectional size of the afterglow chamber at the outlet of the plasma discharge chamber of the first plasma torch;
• wherein the inlet aperture is formed in an upstream wall of the afterglow chamber, wherein the upstream wall of the afterglow chamber partially defines the outlets of each of the plasma discharge chambers, and wherein the upstream wall comprises part of a shielding member configured to reduce air entrainment into the afterglow chamber by the continuous fiber;
• and
• wherein the shielding member defines a shielding wall which extends between the outlets of the plasma discharge chambers and the substrate inlet and is aligned with a wall of the outlets.