Multilayer vacuum window for wide-band microwave plasma diagnostic systems

Roberto Cavazzana, Maurizio Moresco

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Microwave diagnostics, e.g., reflectometry and electron cyclotron emission in plasma machines, often require large windows displaying low attenuation and reflection on a wide band, in addition to some basic features such as vacuum tightness and mechanical robustness. Wide-band matching is usually achieved by coating the window with dielectric layers of suitable permittivity and thickness. On the vacuum side the coating must also be vacuum compatible and resistant to the thermal radiation coming from plasma. On the RFX machine, to satisfy these requirements, a boron nitride disk properly machined on the surface facing the plasma has been clamped to the existing fused silica window. The addition of a Teflon layer on the air side allowed to attain power reflection coefficients as low as 0.025 in the frequency ranges of 26.5-40, 40-56, and 56-75 GHz and as low as 0.01 in the frequency ranges of 75-92 and 92-110 GHz. © 2006 American Institute of Physics.
Original languageEnglish
Article number10E921
Pages (from-to)-
JournalReview of Scientific Instruments
Issue number10
Publication statusPublished - 2006
Externally publishedYes


All Science Journal Classification (ASJC) codes

  • Instrumentation

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