| 摘要 |
A shielded RF antenna system (10) for generating a plasma (16) from a starting material (e.g. a gas) includes a circularly shaped, loop antenna (18) that surrounds a plasma region. A conductive, elongated screen element (20) having an inner surface (22) and an outer surface (24) is wound as a helix around the loop antenna with the inner surface distanced from the antenna. Adjacent edges (34, 36,) of the helical winding are overlapped and an insulator, such as a ceramic, is positioned between the overlapped edges to create a fluid tight seal therebetween. The screen element shields the electrostatic component of the electromagnetic field from the plasma region and prevents plasma from passing through the shield. In addition, the structure allows the insulator to be positioned between the overlapped edges where it is not directly exposed to the plasma.
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