| 摘要 |
A multichannel array structure is provided and a mechanism for establishing a viscous flow within the multichannel array for preventing the flow of particulates (???material) that cause window clouding. A process chamber is provided for confining a process pressure within a process volume with a viewport window along the chamber for viewing at least a portion of the process volume. A ingress port is disposed in the process chamber, and to the process volume, for receiving a flow of process gas in the process volume and an egress port is disposed, and in the process chamber, to the process volume for extracting a flow rate of gas from the process volume. A multichannel array (MCA) is disposed between the viewport window and the process volume of the process chamber. The MCA has a plurality of channels, each of the channels having a diameter and a length. A window chamber is defined between the viewport window and MCA with a chamber window port for receiving gas into the chamber volume. A viscous flow is formed at the window side of the channels in the MCA that prevents material from entering the window chamber and adhering to the window. The viscous flow is established by increasing pressure in the window chamber via the chamber window port, wherein the window chamber pressure exceeds the process pressure, but not enough to substantially increase the flow rate of gas from the process volume. The viscous flow rate is substantially lower than the flow of process gas into the process volume.
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