Dispersion properties and beam excitation of symmetric slow waves in helix traveling wave tubes in the presence of plasma

Abstract

The propagation of the hybrid slow waves in the new helix traveling wave tube, including a dielectric rod, gas plasma layer, and helix sheath is examined. It is assumed that the plasma is strongly magnetized. The dispersion relation of symmetric hybrid slow waves in this waveguide is obtained. It is shown that the frequency increases by increasing the axial wavenumber and the group velocity of slow waves reduces with increasing the dielectric constant. Moreover, by injecting the electron beam in the vacuum area in the waveguide, the symmetric hybrid slow waves are excited and the influence of various parameters on the growth rate of these waves is examined. Furthermore, therequired parameters such as plasma frequency, dielectric constant, and other geometric parameters for waveguide fabrication are expressed. According to this configuration, the allowed region for the operation of this waveguide and its growth rate and other results are obtained.

KEYWORDS:

• Helix traveling wave tube
• gas plasma
• slow waves
• strongly magnetized plasma

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Notes on contributors

M. Vafaei

M. Vafaei was born in Qom, Iran, in 1994. She received the B.S. degree in physics from Qom University, Qom, in 2016, the M.S. degree in physics, University Qom University, in Qom, Iran, in 2019.

M. Nejati

M. Nejati was born in Qom, Iran, in 1982. She received the B.S. degree in physics from Qom University, Qom, in 2004, the M.S. degree in physics from Kashan University, Kashan, Iran, in 2006, and the Ph.D. degree in physics from Shahid Beheshti University, Tehran, Iran, in 2012. Her current research interests include plasma waveguides and plasma photonic crystals.

A. Abdoli-Arani

A. Abdoli-Arani was born in Kashan, Iran. He received the B.S. degree in educational physics from the University of Kashan, Kashan, Iran, the M.Sc. degree in theoretical physics from the University of Tehran, Tehran, Iran, and the Ph.D. degree in plasma physics from University Kashan, Kashan, Iran. His academic grade in University of kashan is associate professor. His current research interests include plasma waveguides, electromagnetic properties of elliptical plasma waveguides, acceleration of charged particles (electron), electromagnetic wave scattering from the plasmas and free electron laser.

A. R. Niknam

A. R. Niknam was born in Shahrood, Iran, in 1965. He received the B.Sc., M.Sc., and Ph.D. degrees in physics from Shahid Beheshti University, Tehran, Iran. He has been a Professor of Physics with the Laser and Plasma Research Institute, Shahid Beheshti University, since 2005. His current research interests include laser-plasma interactions and plasma instabilities.