Atmospheric pressure plasma processing of polymeric materials utilizing close proximity indirect exposure
A plasma treatment method that includes providing treatment chamber including an intermediate heating volume and an interior treatment volume. The interior treatment volume contains an electrode assembly for generating a plasma and the intermediate heating volume heats the interior treatment volume. A work piece is traversed through the treatment chamber. A process gas is introduced to the interior treatment volume of the treatment chamber. A plasma is formed with the electrode assembly from the process gas, wherein a reactive species of the plasma is accelerated towards the fiber tow by flow vortices produced in the interior treatment volume by the electrode assembly.
1. A plasma treatment apparatus comprising:
a treatment chamber comprising: (i) an interior treatment volume having an entrance and exit for processing a workpiece and an asymmetrical electrode assembly for generating a plasma, and (ii) an intermediate heating volume for heating the interior treatment volume;
at least one process gas inlet into the interior treatment volume;
wherein the asymmetrical electrode assembly comprises at least two plasma-generating electrodes that are separated from each other and present on a surface of a dielectric barrier, and wherein the at least two plasma-generating electrodes differ in at least one of a width and a length dimension to provide an asymmetrical geometry of the plasma-generating electrodes.
2. The plasma treatment apparatus of claim 1 , wherein the intermediate heating volume comprises a heating element for heating the interior treatment volume.
3. The plasma treatment apparatus of claim 1 , wherein the intermediate heating volume has an outer shell, and the interior treatment volume is separated from the intermediate heating volume by an inner shell.
4. The plasma treatment apparatus of claim 3 , wherein the outer shell has a cylindrical, rectangular, ellipsoidal, or square geometry.
5. The plasma treatment apparatus of claim 3 , wherein the inner shell has a cylindrical, rectangular, ellipsoidal, or square geometry.
6. The plasma treatment apparatus of claim 1 , wherein the dielectric barrier is composed of silicon oxide (SiO 2 ), borosilicate family of glasses, soda lime glass, silicon nitride (Si 3 N 4 ), alumina (Al 2 O 3 ), aluminosilicates, polyaluminosilicate ceramic (policor), mica and combinations thereof.
7. The plasma treatment apparatus of claim 1 , wherein the electrode assembly comprises upper electrodes separated from at least one lower electrode by said dielectric barrier.
8. The plasma treatment apparatus of claim 7 , wherein a length of the upper electrodes is parallel with a direction of travel the workpiece would take from the entrance to the exit in the interior treatment volume.
9. The plasma treatment apparatus of claim 7 , wherein a length of the upper electrodes is perpendicular with a direction of travel the workpiece would take from the entrance to the exit in the interior treatment volume.
10. The plasma treatment apparatus of claim 1 , wherein the at least two plasma-generating electrodes include an upper electrode on a first surface of the dielectric barrier and a lower electrode on a second surface of the dielectric barrier that is opposite the first surface.
11. The plasma treatment apparatus of claim 10 , wherein at least one of a width and a length dimension of the upper electrode is different than at least one of a width and length dimension of the lower electrode to provide an asymmetrical electrode geometry.
12. The plasma treatment apparatus of claim 10 , wherein each of the upper electrode and the lower electrode has a centrally positioned opening.
13. The plasma treatment apparatus of claim 1 , wherein the at least two plasma-generating electrodes have a same length in a parallel plate configuration.