Skip to main content Accessibility help
×
Hostname: page-component-7b7567c8c-kwt9d Total loading time: 0 Render date: 2026-11-14T09:11:46.158Z Has data issue: false hasContentIssue false

19 - Magnets

Published online by Cambridge University Press:  27 April 2018

Richard G. Carter
Richard G. Carter
Affiliation:
Lancaster University
Get access

Summary

Magnetic fields having well-defined spatial distributions are essential to the operation of many types of vacuum tube. This chapter summarises the theory of magnetism and the properties of soft and hard ferro-magnetic materials. The use of magnetic circuit theory for the design of electro-magnets and permanent magnets is described. The magnets used in vacuum tubes can be divided into coil dominated magnets in which no iron is used to control the flux paths and iron dominated magnets in which the greater part of the flux passes through iron. The theory of coil-dominated magnets employing arrays of coils or solenoids is described with an emphasis on the production of a uniform magnetic field within a volume of space. In iron dominated magnets the shape of the pole-pieces has an important influence on the distribution of the flux in the intervening air gap. The design of iron-dominated magnets for magnetrons, CFAs and linear-beam tubes is discussed with a detailed discussion of the design of periodic permanent magnet (PPM) systems. The results are compared with the results of simulation using finite element methods.

Information

Type
Chapter
Information
Microwave and RF Vacuum Electronic Power Sources , pp. 735 - 764
Publisher: Cambridge University Press
Print publication year: 2018

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.)

Book purchase

Temporarily unavailable

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

Accessibility standard: Unknown

Why this information is here

This section outlines the accessibility features of this content - including support for screen readers, full keyboard navigation and high-contrast display options. This may not be relevant for you.

Accessibility Information

Accessibility compliance for the HTML of this chapter is currently unknown and may be updated in the future.

Save book to Kindle

To save this book to your Kindle, first ensure no-reply@cambridge.org is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about saving to your Kindle.

Note you can select to save to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.

Find out more about the Kindle Personal Document Service.

  • Magnets
  • Richard G. Carter, Lancaster University
  • Book: Microwave and RF Vacuum Electronic Power Sources
  • Online publication: 27 April 2018
  • Chapter DOI: https://doi.org/10.1017/9780511979231.020
Available formats
×

Save book to Dropbox

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/10.1017/9780511979231.020
Available formats
×

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/10.1017/9780511979231.020
Available formats
×