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TUXO01 |
Coupling Microwave Power into ECR Ion Source Plasmas at Frequencies above 20 GHz |
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- C.M. Lyneis, J.Y. Benitez, M.M. Strohmeier, D.S. Todd
LBNL, Berkeley, California, USA
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Electron Cyclotron Resonance (ECR) ion sources have been built to operate at frequencies from 5 GHz to 28 GHz and typically use a plasma chamber that serves as a multi-mode cavity. For small sources operating at 6 to 14 GHz cavity mode-like behavior has been reported. In these cavities the vacuum mode density is low enough that it may be that the RF power distribution can be understood in terms of excitation of a few modes. The large superconducting ECR ion sources, such as VENUS, operating at higher frequencies have a much greater mode density and very strong damping from plasma microwave adsorption. In this type of source, how the RF is launched into the plasma chamber will strongly affect the microwave coupling and the chamber walls will be less important. The VENUS source uses round over-moded TE01 mode waveguide to couple to the plasma, while most modern fusion devices use quasi-gaussian HE11 waves for injection into plasmas. In this paper we will describe the potential advantages of applying this technology to superconducting ECR ion sources as well as designs for doing so with VENUS.
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Slides TUXO01 [18.302 MB]
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