Modeling and Simulation of Relativistic Multiple Electron Beam Generation With Different Energies From a Single-Cathode Potential for High-Power Microwave Sources

Islam, Khandakar Nusrat; Ludeking, L.; Andreev, Andrey D.; Portillo, S.; Elfrgani, Ahmed; Schamiloglu, E.

doi:10.1109/ted.2022.3140408

Cited by 6 publications

(1 citation statement)

References 26 publications

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“…(complex space charge wavenumbers) due to the two-stream instability effect [19]- [21]. Motivated by previous work on two-stream instability amplifiers, Islam et al, [22], [23] have proposed a method to generate a two-stream electron beam with two different energies from a single-cathode potential.…”

Section: Introductionmentioning

confidence: 99%

Reduced Plasma Frequency Calculation Based on Particle-In-Cell Simulations

Mealy¹,

Marosi²,

Capolino³

2022

Preprint

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We propose a scheme to calculate the reduced plasma frequency of a cylindrical-shaped electron beam flowing inside of a cylindrical tunnel, based on results obtained from Particle-in-cell (PIC) simulations. In PIC simulations, we modulate the electron beam using two parallel, non-intercepting, closely-spaced grids which are electrically connected together by a single-tone sinusoidal voltage source. The electron energy and the beam current distributions along the length of the tunnel are monitored after the system is operating at steadystate. We build a system matrix describing the beam's dynamics, estimated by fitting a 2 × 2 matrix that best agrees with the first order differential equations that govern the physics-based system. Results are compared with the theoretical Branch and Mihran model, which is typically used to compute the plasma frequency reduction factor in such systems. Our method shows excellent agreement with the theoretical model, however, it is also general. Our method can be potentially utilized to determine the reduced plasma frequencies of electron beams propagating in differentlyshaped beam tunnels, where no theoretical model yet exists, such as the case of a cylindrical or elliptical electron beam propagating inside of a metallic beam tunnel of cylindrical, square, or elliptical cross-section. It can be applied also to electron beams composed of multiple streams.

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Section: Introductionmentioning

confidence: 99%

Reduced Plasma Frequency Calculation Based on Particle-In-Cell Simulations

Mealy¹,

Marosi²,

Capolino³

2022

Preprint

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The field theory of collective Cherenkov radiation associated with electron beams

Schamiloglu,

Figotin

2024

Physics of Plasmas

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Classical Cherenkov radiation is a celebrated physics phenomenon of electromagnetic (EM) radiation stimulated by an electric charge moving with constant velocity in a three-dimensional dielectric medium. Cherenkov radiation has a wide spectrum and a particular distribution in space similar to the Mach cone created by a supersonic source. It is also characterized by the energy transfer from the charge's kinetic energy to the EM radiation. In the case of an electron beam passing through the middle of an EM waveguide, the radiation is manifested as collective Cherenkov radiation. In this case, the electron beam can be viewed as a one-dimensional non-neutral plasma, whereas the waveguide can be viewed as a slow wave structure. This collective radiation occurs, in particular, in traveling wave tubes (TWTs), and it features the energy transfer from the electron beam to the EM radiation in the waveguide. Based on a first principles Lagrangian field theory, we develop a convincing argument that the collective Cherenkov effect in TWTs is, in fact, a convective instability, that is, amplification. We also recover Pierce's theory as a high-frequency limit of our generalized Lagrangian theory. Finally, we derive for the first time expressions identifying low- and high-frequency cutoffs for amplification in TWTs.

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