Skip to main content
SpringerLink
Log in

Mode Conversion Losses in Expansion Units for ITER ECH Transmission Lines

  • Published:
Journal of Infrared, Millimeter, and Terahertz Waves Aims and scope Submit manuscript

Abstract

The ITER electron cyclotron heating transmission lines will consist of 63.5-mm-diameter corrugated waveguides, each carrying 1 MW of 170 GHz microwaves. These transmission lines must include expansion units to accommodate expansion and contraction along the path from the gyrotron microwave sources to the tokamak. A numerical mode matching code has been developed to calculate power losses due to mode conversion of the operating mode, HE11, to higher order modes as a result of the radial discontinuities in a sliding joint. Two expansion unit designs were evaluated, a simple gap expansion unit and a more complex tapered expansion unit. The gap expansion unit demonstrated loss that oscillated rapidly with expansion length, due to trapped modes within the unit. The tapered expansion unit has been shown to effectively suppress these trapped modes at the expense of increased fabrication complexity. In a gap expansion unit, for a waveguide step size of 2.5 mm, loss can be kept below 0.1 % to a maximum expansion length of 17 mm. Expansion units without corrugation on interior walls were also evaluated. Expansion units that lack corrugations are found to increase mode trapping within the units, though not beyond useful application. The mode matching code developed in this paper was also used to estimate mode conversion loss in vacuum pumpouts for the ECH lines; the estimated loss was found to be negligibly small.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6
Fig. 7
Fig. 8
Fig. 9

Similar content being viewed by others

References

  1. F. Gandini, T. S. Bigelow, B. Becket, J. B. Caughman, D. Cox, C. Darbos, T. Gassmann, M. A. Henderson, O. Jean, K. Kajiwara, N. Kobayashi, C. Nazare, Y. Oda, T. Omori, D. Purohit, D. A. Rasmussen, D. M. S. Ronden, G. Saibene, K. Sakamoto, M. A. Shapiro, K. Takahashi, and R. J. Temkin, Fusion Sci. Technol., 59(4), 709 (2011).

  2. T. Omori, M. A. Henderson, F. Albajar, S. Alberti, U. Baruah, T. S. Bigelow, B. Beckett, R. Bertizzolo, T. Bonicelli, A. Bruschi, J. B. Caughman, R. Chavan, S. Cirant, A. Collazos, D. Cox, C. Darbos, M. R. de Baar, G. Denisov, D. Farina, F. Gandini, T. Gassmann, T. P. Goodman, R. Heidinger, J. P. Hogge, S. Illy, O. Jean, J. Jin, K. Kajiwara, W. Kasparek, A. Kasugai, S. Kern, N. Kobayashi, H. Kumric, J. D. Landis, A. Moro, C. Nazare, Y. Oda, I. Pagonakis, B. Piosczyk, P. Platania, B. Plaum, E. Poli, L. Porte, D. Purohit, G. Ramponi, S. L. Rao, D. A. Rasmussen, D. M. S. Ronden, T. Rzesnicki, G. Saibene, K. Sakamoto, F. Sanchez, T. Scherer, M. A. Shapiro, C. Sozzi, P. Spaeh, D. Strauss, O. Sauter, K. Takahashi, R. J. Temkin, M. Thumm, M. Q. Tran, V. S. Udintsev, and H. Zohm, Fusion Eng. Des., 86(6-8), 951 (2011).

  3. Y. Oda, K. Kajiwara, K. Takahashi, A. Kasugai, M. A. Shapiro, R. J. Temkin, and K. Sakamoto, J. Infrared Millimeter Terahertz Waves, 31(8), 949 (2010).

  4. T. Shimozuma, H. Idei, M. A. Shapiro, R. J. Temkin, S. Kubo, H. Igami, Y. Yoshimura, H. Takahashi, S. Ito, S. Kobayashi, Y. Mizuno, Y. Takita, and T. Mutoh, Plasma Fusion Res., 5, S1029 (2010).

  5. J. Lohr, Y. A. Gorelov, K. Kajiwara, D. Ponce, R. W. Callis, J. L. Doane, R. L. Ellis, H. J. Grunloh, C. P. Moeller, J. Peavey, R. Prater, and J. F. Tooker, Fusion Sci. Technol., 48(2), 1226 (2005).

  6. R. A. Olstad, J. L. Doane, and C. P. Moeller, Fusion Eng. Des. 74(1-4), 331 (2005).

  7. J. L. Doane and R. A. Olstad, Fusion Sci. Technol., 53(1), 39 (2008).

  8. J. L. Doane, Fusion Sci. Technol., 53(1), 159 (2008).

  9. K. Kajiwara, K. Takahashi, N. Kobayashi, A. Kasugai, T. Kobayashi, and K. Sakamoto, Proc. Joint 32nd Int. Conf. Infrared and Millimeter Waves and the 15th Int. Conf. Terahertz Electronics (IRMMW-THz), Cardiff, United Kingdom, September 2–7, 2007, p. 793 (2008).

  10. S. T. Han, E. N. Comfoltey, M. A. Shapiro, J. R. Sirigiri, D. S. Tax, R. J. Temkin, P. P. Woskov, and D. A. Rasmussen, Int. J. Infrared Millimeter Waves, 29(11), 1011 (2008).

  11. M. Cengher, J. Lohr, I. A. Gorelov, W. H. Grosnickle, D. Ponce, and P. Johnson, Proc. 15th Joint Workshop Electron Cyclotron Emission and Electron Cyclotron Resonance Heating (EC-15), Yosemite, California, March 10-13, 2008, p. 483, J. Lohr, Ed., World Scientific Publishing Company, Singapore (2009).

  12. R. A. Olstad, R. W. Callis, J. L. Doane, H. J. Grunloh, and C. P. Moeller, Proc. 15th Joint Workshop Electron Cyclotron Emission and Electron Cyclotron Resonance Heating (EC-15), Yosemite, California, March 10-13, 2008, p. 542, J. Lohr, Ed., World Scientific Publishing Company, Singapore (2009).

  13. R. W. Callis, J. L. Doane, H. J. Grunloh, K. Kajiwara, A. Kasugai, C. P. Moeller, Y. Oda, R. A. Olstad, K. Sakamoto, and K. Takahashi, Fusion Eng. Des., 84(2-6), 526 (2009).

  14. S. Park, J. Jeong, W. Namkung, M.-H. Cho, Y. S. Bae, W.-S. Han, and H.-L. Yang, Fusion Sci. Technol., 55(1), 56 (2009).

  15. M. A. Shapiro, E. J. Kowalski, J. R. Sirigiri, D. S. Tax, R. J. Temkin, T. S. Bigelow, J. B. Caughman, and D. A. Rasmussen, Fusion Sci. Technol., 57(3), 196 (2010).

  16. J. L. Doane and C. P. Moeller, Int. J. Electronics, 77(4), 489 (1994).

  17. J. Uher, J. Bornemann, and U. Rosenberg, in Waveguide Components for Antenna Feed Systems: Theory and CAD (Artech House, Norwood, MA, 1993) pp. 9–51.

  18. A. D. Olver, P. J. B. Clarricoats, A. A. Kishk, L. Shafai, Microwave Horns and Feeds, ed. by P. J. B. Clarricoats, Y. Rahmat-Samii, J. R. Wait (IEEE Press, New York, 1994), pp. 106-117.

  19. J. M. Neilson, P. E. Latham, M. Caplan, and W. G. Lawson, IEEE Trans. Microw. Theory Tech., 37(8), 1165 (1989).

  20. G. G. Denisov, D. A. Lukovnikov, W. Kasparek, and D. Wagner, Int. J. Infrared Millimeter Waves, 17(5), 933 (1996).

  21. E. J. Kowalski, D. S. Tax, M. A. Shapiro, J. R. Sirigiri, R. J. Temkin, T. S. Bigelow, and D. A. Rasmussen, IEEE Trans. Microw. Theory Tech., 58(11), 2772 (2010).

  22. Cascade User Manual, version 4.0. (Lexam Research, Redwood City, CA, 2013).

  23. J. L. Doane, Int. J. Infrared Millimeter Waves, 14(2), 363 (1993).

  24. C. Dragone, IEEE, Trans. Microw. Theory Tech., 28(7), 704 (1980).

  25. E. A. Nanni, S. K. Jawla, M. A. Shapiro, P. P. Woskov, and R. J. Temkin, J. Infrared Millimeter Terahertz Waves, 33(7), 695 (2012).

Download references

Acknowledgments

This research was supported by the U.S. Department of Energy, Office of Fusion Energy Sciences and by the U.S. ITER Project managed by Battelle / Oak Ridge National Laboratory.

Author information

Authors and Affiliations

  1. Plasma Science & Fusion Center, Massachusetts Institute of Technology, 167 Albany St., Bldg. NW16, Cambridge, MA, 02139, USA

    S. C. Schaub, M. A. Shapiro & R. J. Temkin

  2. US ITER Project, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA

    G. R. Hanson

Authors
  1. S. C. Schaub
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. M. A. Shapiro
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. R. J. Temkin
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. G. R. Hanson
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to S. C. Schaub.

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Schaub, S.C., Shapiro, M.A., Temkin, R.J. et al. Mode Conversion Losses in Expansion Units for ITER ECH Transmission Lines. J Infrared Milli Terahz Waves 37, 72–86 (2016). https://doi.org/10.1007/s10762-015-0190-4

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s10762-015-0190-4

Keywords

Search

Navigation