Hostname: page-component-cd9895bd7-q99xh Total loading time: 0 Render date: 2024-12-19T03:03:33.319Z Has data issue: false hasContentIssue false
  • English
  • Français

Effects of dielectric discontinuity on the dispersion characteristics of the tape helix slow-wave structure with two metal shields

Published online by Cambridge University Press:  15 December 2011

Yu Zhang ,
Jinliang Liu ,
Shiwen Wang ,
Xuliang Fan ,
Hongbo Zhang  and
Jiahuai Feng
Yu Zhang*
Affiliation:
College of Opto-electronic Science and Engineering, National University of Defense Technology, Changsha, China
Jinliang Liu
Affiliation:
College of Opto-electronic Science and Engineering, National University of Defense Technology, Changsha, China
Shiwen Wang
Affiliation:
College of Opto-electronic Science and Engineering, National University of Defense Technology, Changsha, China
Xuliang Fan
Affiliation:
College of Opto-electronic Science and Engineering, National University of Defense Technology, Changsha, China
Hongbo Zhang
Affiliation:
College of Opto-electronic Science and Engineering, National University of Defense Technology, Changsha, China
Jiahuai Feng
Affiliation:
College of Opto-electronic Science and Engineering, National University of Defense Technology, Changsha, China
*
Address correspondence and reprint requests to: Yu Zhang, College of Opto-electronic Science and Engineering, National University of Defense Technology, Changsha, 410073, China. E-mail: [email protected]
Get access Rights & Permissions [Opens in a new window]

Abstract

In the tape helix slow-wave system, discontinuous dielectrics have great effects on the dispersion characteristics. In this paper, the tape helix slow-wave system, including an inner and an outer metal shield, tape helix, nylon support and de-ionized water as filling dielectric, was analyzed. Effects of dielectric discontinuity caused by the support dielectric and filling dielectric on the dispersion characteristics were studied in detail. The dispersion relations, phase velocities, slow-wave coefficients and electric lengths of the spatial harmonics in the system were calculated. Results showed that, if the permittivity of support dielectric was smaller than that of the filling dielectric, frequencies of the spatial harmonics in the system rose, phase velocities and slow-wave coefficients increased, the slow-wave effect of the system was weakened so that the previous electric length was shortened. The reverse condition corresponded to the reverse results, and the electromagnetic simulation also proved it. By use of the helical pulse forming line of accelerator based on the studied tape helix slow-wave system, the electric lengths of the system were tested as 188.5 ns and 200 ns in experiment when the thicknesses of nylon support were 6 mm and 3 mm, respectively. The theoretical calculation results 198 ns and 211 ns basically corresponded to experimental results, which only had relative errors as 5 and 5.5%, respectively.

Keywords

AcceleratorDielectric discontinuityDispersion relationElectric lengthPulse forming lineSpatial harmonicsTape helix slow-wave structure
Type
Research Article
Information
Laser and Particle Beams , Volume 29 , Issue 4 , December 2011 , pp. 459 - 469
Copyright
Copyright © Cambridge University Press 2011

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

Ahgostino, S.D., Emma, F. & Paoloni, C. (1998). Accurate analysis of helix slow-wave structures. IEEE Trans. Electron Devices 45, 1605–1613.CrossRefGoogle Scholar
Chen, X.-B., Liu, J.-L. & Zhang, H.-B. (2010). Improving the output voltage waveform of an intense electron-beam accelerator based on helical type Blumlein pulse forming line. Phys. Rev. 13, 070402.Google Scholar
Chen, X.-B., Liu, J.-L. & Zhang, Y. (2009). Effect of a transition section between the Blumlein line and a load on the output voltage of gigawatt intense electron-beam accelerators. Phys. Rev. 12, 110401.Google Scholar
Cheng, X.-B., Liu, J.-L., Qian, B.-L. & Zhang, J.-D. (2009). Effect of transition section between the main switch and middle cylinder of Blumlein pulse forming line on the diode voltage of intense electron-beam accelerators. Laser Part. Beams 27, 439–447.CrossRefGoogle Scholar
Chernin, D, Antonsen, T.M. & Levush, B. (1999). Exact treatment of the dispersion and beam interaction impedance of a thin tape helix surrounded by a radially stratified dielectric. IEEE Trans. Electron. Devices 46, 1472–1483.Google Scholar
Datta, S.K. & Kumar, L. (2009). A simple equivalent circuit analysis of the dielectric loss in a helical slow-wave structure of a travelling-wave tube. IEEE Trans. Electron. Devices 56, 1338–1343.Google Scholar
Datta, S.K., Naidu, N.B. & Rao, P.R. (2010). Simple formulas for attenuation characteristics of asymmetric helical slow-wave structures of travelling-wave tubes. IEEE Trans. Electron. Devices 57, 1447–1454.Google Scholar
Dialetis, D., Chernin, D. & Antonsen, T.M. (2009). Accurate representation of attenuation in helix TWT simulation codes. IEEE Trans. Electron. Devices 56, 935–944.CrossRefGoogle Scholar
Friedman, S., Limpaecher, R. & Sirchis, M. (1988). Compact energy storage using a modified-spiral PFL. Power Modul. Sympos. 1988, 360–366.Google Scholar
Ge, X.-J., Zhong, H.-H. & Qian, B.-L. (2010). Asymmetric-mode competition of in a relativistic backward wave oscillator with a coaxial slow-wave structure. Appl. Phys. Lett. 97, 241501.Google Scholar
Ghosh, S., Jain, P.K. & Basu, B.N. (1997). Rigorous tape analysis of inhomogeneously-loaded helical slow-wave structures. IEEE Trans. Electron. Devices 44, 1158–1168.CrossRefGoogle Scholar
Johnson, H.R., Everhart, T.E. & Siegman, A.E. (1956). Wave Propagation on Multifilar Helices. IEEE Trans. Electron. Devices 2, 18–24.Google Scholar
Kartikeyan, M.V., Sinha, A.K. & Bandopadhyay, H.N. (1999). Effective simulation of the radial thickness of helix for broad band, practical TWT's. IEEE Trans. Plasma Sci. 27, 1115–1123.CrossRefGoogle Scholar
Kompfner, R. & Willianms, N.T. (1953). Backward-wave tubes. Inst. Elec. Eng. 41, 1602–1611.Google Scholar
Kompfner, R. (1947). Traveling wave tube as amplifier at microwaves. Inst. Elec. Eng. 35,124.Google Scholar
Korovin, S.D., Gubanov, V.P., Gunin, A.V., Pegel, I.V. & Stepchenko, A.S. (2001). Repetitive nanosecond high-voltage generator based 14 on spiral forming line. The 28th IEEE international Conference on Plasma Science, Las Vegas, NV, 1249–1251.Google Scholar
Liu, J.-L., Cheng, X.-B., Qian, B.-L., Ge, B., Zhang, J. & Wang, X.-X. (2009). Study on strip spiral Blumlein line for the pulsed forming line of intense electron-beam accelerators. Laser Part. Beams 27, 95–102.CrossRefGoogle Scholar
Liu, J.-L., Li, C.-L. & Zhang, J.-D. (2006). A spiral strip transformer type electron-beam accelerator. Laser Part. Beams 24, 355–358.CrossRefGoogle Scholar
Liu, J.-L., Yin, Y. & Ge, B. (2007 a). A compact high power pulsed modulator based on spiral Blumlein line. Rev. Sci. Instrum. 78,103302.Google Scholar
Liu, J.-L., Zhan, T.-W., Zhang, J., Liu, Z.-X., Feng, J.-H., Shu, T., Zhang, J.-D. & Wang, X.-X. (2007 b). A Tesla pulse transformer for spiral water pulse forming line charging. Laser Part. Beams 25, 305–312.CrossRefGoogle Scholar
Lopes, D.T. & Motta, C.C. (2005). Loss tape-helix analysis of slow-wave-structures. IEEE Pulsed Power Conference 2005, 222–224.CrossRefGoogle Scholar
Pierce, J.R. (1950). Traveling Wave Tubes. New York: D.Van Nostrand Co. Inc.Google Scholar
Sensiper, S. (1955). Electromagnetic wave propagating on helical structures (A review of survey of recent progress). Inst. Elec. Eng. 43, 149–161.Google Scholar
Shidara, T., Akemoto, M. & Yoshidda, M. (1991). Blumlein-type X-band klystron modulator for Japan linear collider. Part. Accel. Conf. 2, 1034–1036.Google Scholar
Swift-Hook, D.T. (1958). Dispersion curves for a helix in a glass tube. Inst. Elec. Eng. 105B, 747–755.Google Scholar
Tien, P.K. (1954). Bifilar helix for backward-wave oscillators. Inst. Elec. Eng. 42, 1137–1142.Google Scholar
Watkins, D.A. & Ash, E.A. (1954). The helix as a backward-wave circuit structure. J. Appl. Phys. 25, 782–790.Google Scholar