Eur. Phys. J. Plus (2016) 131: 353
https://doi.org/10.1140/epjp/i2016-16353-6

Regular Article

Plasma effects on the growth rate of a helix magnetron-type conducting cylinder

¹ The Department of Physics, Khorramabad Branch, Islamic Azad University, Khorramabad, Iran
² The Plasma Physics Research Center, Science and Research Branch, Islamic Azad University, Tehran, Iran

^* e-mail: Dehghaninejad.amin@gmail.com

Received: 11 June 2016
Accepted: 24 August 2016
Published online: 5 October 2016

Abstract

The linear theory of magnetron amplifier in the presence of the partially plasma loaded sheath helix is presented. The hollow electron beam and plasma column are exposed to the axial magnetic field. The dispersion relation is obtained by using the appropriate boundary conditions. The effects of electron beam, plasma column parameters and sheath helix are studied numerically on the gain. The numerical results show that the presence of the plasma column considerably increases the gain. It is shown that the bandwidth increases by increasing the plasma density. One of the interesting results are that the maximum gain occurs at the special value of the plasma and beam radius. The maximum of gain occurs when the helix approaches the vane. The results show that the gain and bandwidth at lower harmonics are greater than at higher harmonics. The gain and bandwidth in the presence of the plasma column are larger than when applying the dielectric rod.