Dispersive Nature of the FEL Amplifiers in the Whistler Mode

  • Ram GopalEmail author
  • M. Sunder Rajan
  • Priti Sharma
  • Abhinav K. Gautam
Conference paper
Part of the Advances in Intelligent Systems and Computing book series (AISC, volume 1154)


The analytical formalism for whistler-pumped FEL amplifiers in collective Raman regime is developed. Compton regime (CR) has also feasible for the low-current gain; however, in practical, it does not exist for reasonable growth rate due to require of extremely high magnetic fields density (i.e., 10–15 T) to operate up to 200–250 GHz frequencies; hence, Raman regime plays an important role with the finite space charged mode only. The dispersive nature of the whistler-pumped FEL amplifiers is sensitive to frequency of electron cyclotron, plasma frequency, and magnetic fields of the amplifiers. The simultaneously of the pumped frequency with strong magnetic fields and plasma frequency should be synchronized for electron cyclotron frequency, which can rapidly increases the wiggler wave number to the radiation of amplification in the slow-whistler mode for high frequencies from millimeter to the sub-millimeter ranges. It is also clear that the background plasma should be lesser than the beam density for the charge neutralization and guiding of the signal into waveguides; hence, the plasma density can also improve the stability of high frequencies. In Raman regime, the growth rate is larger while it decreases as increases the frequency of operations and vice versa. The tapering of an axial field also plays a typical role to raise the efficiency as well as reduction in the length of interaction with axis.


FEL amplifiers Axial field Wiggler field and whistler 


  1. 1.
    Pant, K.K., Tripathi, V.K.: Free electron laser operation in the whistler mode. IEEE Trans. Plasma Sci. 22(3) (1994)Google Scholar
  2. 2.
    Sharma, A., Tripathi, V.K.: A plasma filled gyrotron pumped free electron laser. Phys. Plasmas 3, 3116 (1996). Scholar
  3. 3.
    Liu, C.S., Tripathi, V.K.: Interaction of Electromagnetic Waves with Electron Beams and Plasmas. World Scientific (1994)Google Scholar
  4. 4.
    Marshall, T.C.: Free Electron Lasers. MacMillan, New York (1985)Google Scholar
  5. 5.
    Shea, P.G.O., Freund, H.P.: Free electron lasers: status and applications. 292(5523), 1853–1858 (2001).
  6. 6.
    Sharma, A., Tripathi, V.K.: Kinetic theory of a whistler-pumped free electron laser. Phys. Fluids B 5(1) (1993).
  7. 7.
    Sharma, A., Tripathi, V.K.: A whistler pumped free electron laser. Phys. Fluids 3I, 3375–3378 (1988)CrossRefGoogle Scholar
  8. 8.
    Pant, K.K., Tripathi, V.K.: Nonlocal theory of a whistler pumped free electron laser. Phys. Plasmas 1, 1025 (1994)CrossRefGoogle Scholar
  9. 9.
    Chung, T.H., Kim, S.H., Lee, J.K.: Simulation of tapered FEL amplifiers in millimetre and infrared regions. Nuclear Instrum. Phys. Res. A 331, 482–486 (1993)CrossRefGoogle Scholar
  10. 10.
    Gold, S.H., Hardesty, D.L., Kinkead, A.K., Barnett, L.R.: High gain 35-GHz free electron laser amplifier experiment. Phys. Rev. Lett. 52(14), 1218–1221 (1984)CrossRefGoogle Scholar
  11. 11.
    Gold, S.H., Black, W.M., Freund, H.P., Granatstein, V.L., Kinkead, A.K.: Radiation growth in a millimeter-wave free electron laser operating in the collective Regime. Phys. Fluids 27(3), 746–754 (1984).
  12. 12.
    Gold, S.H., Freund, H.P., Bowie: free electron laser with tapered axial magnetic field. The United States of America as represented by the Secretary of the Navy, Patent Number: 4,644,548, Washington, DC (1987)Google Scholar
  13. 13.
    Orzechowski, T.J., Anderson, B.R., Fawley, W.M., Prosnitz, D., Scharlemann, E.T., Yarema, S.M.: High gain and high extraction efficiency from a free electron laser amplifier operating in the millimeter wave regime. Nuclear Instrum. A 250, 144–149 (1986)CrossRefGoogle Scholar
  14. 14.
    Orzeehowski, T.J., Anderson, B.R., Clark, J.C., Fawley, W.M., Paul, A.C., Prosnitz, D., Scharlemann, E.T., Yarema, S.M.: Phys. Rev. Lett. 57(17) (1986)Google Scholar
  15. 15.
    Freund, H.P.: Comparison of free-electron laser amplifiers based on a step-tapered optical klystron and a conventional tapered wiggler. Phys. Rev. 16, 060701 (2013)Google Scholar
  16. 16.
    Freund, H.P., Ganguly, A.K.: Nonlinear simulation of a high-power, collective free electron laser. IEEE Trans. Plasma Sci. 20(3) (1992)Google Scholar
  17. 17.
    Gardelle, J., Labrouche, J., Taillandier, P.-L.: Free electron laser simulations: effects of beam quality and space charge. Phys. Rev. 50(6) (1994)Google Scholar
  18. 18.
    Parker, R.K., Jackson, B.H., Gold, S.H., Freund, H.P., Granatstein, V.L., Efthimion, P. C., Kinkead, A.K.: Axial magnetic-field effects in a collective-interaction free electron laser at millimeter wavelengths. Phys. Rev. Lett. 48(4) (1982)Google Scholar
  19. 19.
    Gopal, R., Jain, P.K.: Tapering effect of an axial magnetic field on whistler-pumped amplifier. Eng. Sci. Technol. Int. J. 8(2), 4–10 (2018)Google Scholar
  20. 20.
    Gopal, R., Jain, P.K.: Effect of axial magnetic field tapering on whistler-pumped FEL amplifier in collective Raman regime operation. Int. J. Eng. Technol. 7(4), 2044–2050 (2018). Scholar
  21. 21.
    Gopal, R., Jain, P.K.: Design methodology and simulation study of a free electron laser amplifier. Int. J. Eng. Technol. 7(4), 3175–3181 (2018). Scholar

Copyright information

© Springer Nature Singapore Pte Ltd. 2020

Authors and Affiliations

  • Ram Gopal
    • 1
    Email author
  • M. Sunder Rajan
    • 2
  • Priti Sharma
    • 3
  • Abhinav K. Gautam
    • 4
  1. 1.Department of Electronics EngineeringCRMT, Indian Institute of Technology (Banaras Hindu University)VaranasiIndia
  2. 2.Faculty of Electrical and Computer EngineeringInstitute of Technology, Arba Minch UniversityArba MinchEthiopia
  3. 3.Department of Electronics and Communication EngineeringUNSIET, Purvanchal UniversityJaunpurIndia
  4. 4.Department of Electrical EngineeringKamla Nehru Institute of TechnologySultanpurIndia

Personalised recommendations