[Table of Contents]

Plasma and Fusion Research

Volume 2, S1030 (2007)

Regular Articles

Protection Filters in ECEI Systems for Plasma Diagnostics
Z. SHEN, N. ITO1), Y. LIANG, L. LIN, C. W. DOMIER, M. JOHNSAON, N. C. LUHMANN, A. MASE1) and E. SAKATA2)
Department of Electrical and Computer Engineering, UC Davis, USA
1)
Art, Science and Technology Center for Cooperative Research, Kyushu University, Japan
2)
Kyushu Hitachi Maxell, Ltd, Japan
(Received 4 December 2006 / Accepted 28 February 2007 / Published 20 November 2007)

Abstract

For plasma diagnostic imaging systems such as the electron cyclotron emission imaging (ECEI) system, spurious rf heating power may saturate or even damage the mixer arrays. Without protection, the sensitivity of the mixers can significantly decrease or in the extreme case, the diodes can even be burnt. A metallic dichroic plate is usually used to rejection the spurious rf heating power. However, as a high pass filter, the dichroic plate can not be used when the frequency of the heating power is in the middle of the frequency range of interest. Consequently, a frequency selective surface (FSS) has been introduced as a planar filter in ECEI systems. FSSs can work as low pass, high pass, and band stop filters according to the various system requirements. Also, as a thin, light, planar filter, it is very easy to mount in imaging systems. This paper will focus on the design and fabrication of the FSS notch filter applied in TEXTOR, which is used to protect the imaging array from stray 140 GHz ECRH power. The filter is used in TEXTOR due to its deep rejection, and excellent angle insensitivity. The design procedure will be presented. More FSS applications will be talked in this paper. The new fabrication technique Electro Fine Forming (EF2) technology will also be introduced. FSS filters in the millimeter wave range also have possible applications in imaging systems in other fusion machines such as KSTAR, DIIID, and LHD.

Keywords

plasma diagnostic, frequency selective surface, electro fine forming technology, notch filter, beam splitter, dichroic plate

DOI: 10.1585/pfr.2.S1030

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References

  • [1] Ben A. Munk, “Frequency Selective Surfaces Theory and Design”, Wiley, 2000.
  • [2] H.J. van der Meiden, Rev. Sci. Instrum. 70 (6), 2861 (1999).
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  • [4] Z. Shen et al., IEEE Antenna & Propagation Society International Symposium, 4191 (2006).
  • [5] N. Ito et al., “Advanced fabrication method of planar components for plasma diagnostics”, Plasma and Fusion Research, 2006.
  • [6] Y. Liang, master thesis, “140 GHz quasi-optical notch filter”.
  • [7] Z. shen, master thesis, “Frequency selective surface notch filter for plasma imaging diagnostics”.
  • [8] J. Wang, dissertation, “Microwave Imaging Diagnostics for Plasma Fluctuation Studies”.
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  • [10] L. Lin, Master thesis, “280 GHz Quasi-optical Millimeter Wave Receiver System for Collective Scatter”.

This paper may be cited as follows:

Z. SHEN, N. ITO, Y. LIANG, L. LIN, C. W. DOMIER, M. JOHNSAON, N. C. LUHMANN, A. MASE and E. SAKATA, Plasma Fusion Res. 2, S1030 (2007).