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19 - Magnets

Published online by Cambridge University Press:  27 April 2018

Richard G. Carter
Richard G. Carter
Affiliation:
Lancaster University
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Summary

Electron and X-ray emission and voltage breakdown caused by static, pulsed, and radio-frequency electric fields are important for the operation of vacuum tubes and also set limits to their performance. The physical principles of thermionic, field enhance, field, photo-electric and secondary electron emission from solid surfaces and the generation of X-rays are reviewed. The construction and properties of the principal types of thermionic cathode are described together with a brief review of cold cathodes employing field emission. Voltage breakdown may occur in vacuum tubes both inside and outside the vacuum envelope and through insulators. The physics of each type of electrostatic breakdown are reviewed. The theory of r.f. vacuum breakdown (multipactor) is discussed in detail both with and without the presence of a static magnetic field revealing the conditions under which a discharge may occur.
Type
Chapter
Information
Microwave and RF Vacuum Electronic Power Sources , pp. 735 - 764
Publisher: Cambridge University Press
Print publication year: 2018

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References

Gittins, J. F., Power Travelling-Wave Tubes. English Universities Press, 1965.Google Scholar
Harrold, W. and Reid, W., ‘Permanent magnets for microwave devices’, IEEE Transactions on Magnetics, vol. 4, pp. 229–239, 1968.CrossRefGoogle Scholar
Smith, M. J. and Phillips, G., Power Klystrons Today. Taunton, UK: Research Studies Press, 1995.Google Scholar
Carter, R. G. Electromagnetism for Electronic Engineers. Available at: http://bookboon.com/en/electromagnetism-for-electronic-engineers-ebook (accessed 5 October 2017), 2010.Google Scholar
Carter, G. W., The Electromagnetic Field in its Engineering Aspects, 2nd ed. London: Longman, 1967.Google Scholar
Bleaney, B. I. and Bleaney, B., Electricity and Magnetism. London: Oxford University Press, 1957.Google Scholar
MacCaig, M., Permanent Magnets in Theory and Practice. London: Pentech Press, 1987.Google Scholar
Edwards, A., ‘Magnet design and selection of material’, in Hadfield, D., ed., Permanent Magnets and Magnetism. London: Iliffe, pp. 191–296, 1962.Google Scholar
Upson, W. L. and Furth, E. L., ‘Abridgment of magnetic leakage and fringing flux calculations’, Journal of the A.I.E.E., vol. 47, pp. 340–344, 1928.CrossRefGoogle Scholar
Sykulski, J., Computational Magnetics. Springer Science & Business Media, 2012.Google Scholar
Infolytica Corp., ‘Gemini’, Montreal, Canada, 1966.Google Scholar
Campbell, P., Permanent Magnet Materials and Their Application. Cambridge University Press, 1996.Google Scholar
Kirchmayr, H. R., ‘Permanent magnets and hard magnetic materials’, Journal of Physics D: Applied Physics, vol. 29, p. 2763, 1996.CrossRefGoogle Scholar
Carter, R. G., Electromagnetism for Electronic Engineers, 2nd ed. London: Chapman & Hall, 1992.Google Scholar
Kaye, G. W. C. and Laby, T. H. Tables of Physical and Chemical Constants. Available at: www.kayelaby.npl.co.uk/ (accessed 5 October 2017), 2014.Google Scholar
Magdev Ltd, Permanent Magnets. Available at: www.magdev.co.uk/permanent-magnets (accessed 5 October 2017), 8 August 2017.Google Scholar
Delta Magnets, Permanent Magnets. Available at: www.magdev.co.uk/permanent-magnets (accessed 5 October 2017), 2011.Google Scholar
Bamford, A. J. et al., ‘A 1-MW L-band coaxial magnetron with separate cavity’, IEEE Transactions on Electron Devices, vol. 14, pp. 844–851, 1967.CrossRefGoogle Scholar
Bhasavanich, D. and Hammon, H. G., III, ‘Pulsed magnet system considerations for repetitive operation of high-power magnetrons’, IEEE Transactions on Electron Devices, vol. 38, pp. 791–795, 1991.CrossRefGoogle Scholar
Dai, Y. et al., ‘Design study on A 9.2 T NbTi superconducting magnet with long-length uniform axial field’, IEEE Transactions on Applied Superconductivity, vol. 25 (3), June, paper no. 4101204, 2015.CrossRefGoogle Scholar
Hirose, R. et al., ‘Development of 7 T cryogen-free superconducting magnet for gyrotron’, IEEE Transactions on Applied Superconductivity, vol. 18, pp. 920–923, 2008.CrossRefGoogle Scholar
Smythe, W. R., Static and Dynamic Electricity, 3rd ed. New York: McGraw-Hill, 1950.Google Scholar
McKeehan, L., ‘Combinations of circular currents for producing uniform magnetic fields’, Review of Scientific Instruments, vol. 7, pp. 150–153, 1936.CrossRefGoogle Scholar
Garrett, M. W., ‘Axially symmetric systems for generating and measuring magnetic fields. Part I’, Journal of Applied Physics, vol. 22, pp. 1091–1107, 1951.CrossRefGoogle Scholar
Carter, R. G., ‘Coil-system design for production of uniform magnetic-fields’, Proceedings of the Institution of Electrical Engineers-London, vol. 123, pp. 1279–1283, 1976.CrossRefGoogle Scholar
Franzen, W., ‘Generation of uniform magnetic fields by means of air-core coils’, Review of Scientific Instruments, vol. 33, pp. 933–938, 1962.CrossRefGoogle Scholar
Gosling, W. and Cunningham, M. J., ‘Gapped solenoid as a means of producing a highly uniform magnetic field over an extended volume’, Proceedings of the Institution of Electrical Engineers, vol. 121, pp. 1589–1593, 1974.CrossRefGoogle Scholar
Montgomery, D. B., Solenoid Magnet Design. New York: Wiley-Interscience, 1969.Google Scholar
Russenschuck, S., Field Computation for Accelerator Magnets: Analytical and Numerical Methods for Electromagnetic Design and Optimization. John Wiley & Sons, 2011.Google Scholar
Staprans, A. et al., ‘High-power linear-beam tubes’, Proceedings of the IEEE, vol. 61, pp. 299–330, 1973.CrossRefGoogle Scholar
Worcester, W. G. et al., ‘Light-weight aluminum foil solenoids for traveling-wave tubes’, IRE Transactions on Electron Devices, vol. 3, pp. 70–74, 1956.CrossRefGoogle Scholar
Glass, R. C. and Gottfeldt, P., ‘Aluminum foil solenoids for traveling-wave tubes’, IRE Transactions on Electron Devices, vol. 4, p. 186, 1957.CrossRefGoogle Scholar
Perigo, E. A. et al., ‘Design of a multi-sections solenoid for power microwave tubes’, in IEEE MTT-S International Conference on Microwave and Optoelectronics, pp. 233–236, 2005.Google Scholar
Borodin, D. and Einat, M., ‘Copper solenoid design for the continuous operation of a second harmonic 95-GHz gyrotron’, IEEE Transactions on Electron Devices, vol. 61, pp. 3309–3316, 2014.CrossRefGoogle Scholar
Harrison, J., ‘A computer study of uniform-field electrodes’, British Journal of Applied Physics, vol. 18, p. 1617, 1967.CrossRefGoogle Scholar
Tanabe, J. T., Iron Dominated Electromagnets: Design, Fabrication, Assembly and Measurements. Singapore: World Scientific, 2005.CrossRefGoogle Scholar
Lebacqz, J., ‘High power klystrons’, IEEE Transactions on Nuclear Science, vol. 12, pp. 86–95, 1965.CrossRefGoogle Scholar
Fu, C. et al., ‘A type of tube-shaped permanent magnet focusing system of high-power klystron’, in Asia-Pacific Microwave Conference Proceedings, vol. 1, pp. 333–335, 1997.Google Scholar
Clarke, J. P. and Leupold, H. A., ‘Shaping of cylindrically symmetric magnetic fields with permanent magnets’, IEEE Transactions on Magnetics, vol. 22, pp. 1063–1065, 1986.CrossRefGoogle Scholar
Fuwa, Y. et al., ‘Focusing system with permanent magnets for klystrons’, IEEE Transactions on Applied Superconductivity, vol. 24, pp. 1–5, 2014.CrossRefGoogle Scholar
Abe, D. K. and Calame, J. P., ‘Advanced materials technologies’, in Barker, R. J. et al., eds, Modern Microwave and Millimeter-Wave Power Electronics. Piscataway, NJ: IEEE Press, pp. 649–689, 2005.Google Scholar
Leupold, H. et al., ‘Permanent magnet sources for extended interaction klystrons’, Journal of Applied Physics, vol. 70, pp. 6624–6626, 1991.CrossRefGoogle Scholar
Leupold, H. and Potenziani, E. II, ‘Augmentation of field uniformity and strength in spherical and cylindrical magnetic field sources’, Journal of Applied Physics, vol. 70, pp. 6621–6623, 1991.CrossRefGoogle Scholar
Peng, Q. L. et al., ‘Axial magnetic field produced by axially and radially magnetized permanent rings’, Journal of Magnetism and Magnetic Materials, vol. 268, pp. 165–169, 2004.CrossRefGoogle Scholar
Sterzer, F. and Siekanowicz, W., ‘The design of periodic permanent magnets for focusing of electron beams’, RCA Review, vol. 18, pp. 39–59, 1957.Google Scholar
Sterrett, J. E. and Heffner, H., ‘The design of periodic magnetic focusing structures’, IRE Transactions on Electron Devices, vol. 5, pp. 35–42, 1958.CrossRefGoogle Scholar
Schindler, M., ‘The magnetic field and flux distributions in a periodic focusing stack for traveling-wave tubes’, RCA Review, vol. 21, pp. 414–436, 1960.Google Scholar
Schindler, M., ‘An improved procedure for the design of periodic-permanent-magnet assemblies for traveling-wave tubes’, IEEE Transactions on Electron Devices, pp. 942–949, 1966.CrossRefGoogle Scholar
Corsi, M. et al., ‘Graphical method for optimum design of periodic magnetic focusing structures’, IEEE Transactions on Electron Devices, vol. 21, pp. 2–11, 1974.CrossRefGoogle Scholar
Santra, M. et al., ‘An improved analysis of PPM focusing structures including the effect of magnetic saturation in the iron pole pieces’, IEEE Transactions on Electron Devices, vol. 56, pp. 974–980, May 2009.CrossRefGoogle Scholar
Kory, C. L., ‘Effect of geometric azimuthal asymmetries of PPM stack on electron beam characteristics [TWTs]’, IEEE Transactions on Electron Devices, vol. 48, pp. 38–44, 2001.CrossRefGoogle Scholar
Leupold, H. A. and Clarke, J. P., ‘Bulk reduction and field enhancement in periodic permanent-magnet structures’, IEEE Transactions on Electron Devices, vol. 34, pp. 1868–1872, August 1987.CrossRefGoogle Scholar
Leupold, H. A. et al., ‘Lightweight permanent magnet stack for traveling-wave tubes’, Journal of Applied Physics, vol. 67, pp. 4656–4658, 1990.CrossRefGoogle Scholar
Santra, M. et al., ‘Analysis of long-periodic permanent magnet structures for electron beam focusing’, IEEE Transactions on Electron Devices, vol. 60, pp. 1776–1781, 2013.CrossRefGoogle Scholar

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  • Magnets
  • Richard G. Carter, Lancaster University
  • Book: Microwave and RF Vacuum Electronic Power Sources
  • Online publication: 27 April 2018
  • Chapter DOI: https://doi.org/10.1017/9780511979231.019
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To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Dropbox.

  • Magnets
  • Richard G. Carter, Lancaster University
  • Book: Microwave and RF Vacuum Electronic Power Sources
  • Online publication: 27 April 2018
  • Chapter DOI: https://doi.org/10.1017/9780511979231.019
Available formats
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Save book to Google Drive

To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Google Drive.

  • Magnets
  • Richard G. Carter, Lancaster University
  • Book: Microwave and RF Vacuum Electronic Power Sources
  • Online publication: 27 April 2018
  • Chapter DOI: https://doi.org/10.1017/9780511979231.019
Available formats
×