Numerical investigations on the effects of electron beam misalignment on beam-wave interaction in a high-power coaxial gyrotron

The transition phase between two nonlinear regimes of electron-beam–wave interaction depending on the amplitude and the nature of the effective dissipation is investigated with the help of numerical simulations. Effective dissipation due to wave escaping to infinity out of the beam–wave interaction region as well as to collisions in the background plasma is considered. If the dissipation is strong enough, the evolution of the electron beam proceeds in a general way, independently of the type of dissipation and of the nature of the considered waves: structures of strongly concentrated electron bunches are formed. These bunches are not trapped in the wave, and decelerate continuously owing to friction on waves: in the presence of dissipation, the usual quasiperiodic exchange of energy between the wave and the trapped particles, which prevents the wave from collapsing, does not occur. Considering beam interaction with a finite number of waves (modulated wave packet), it is shown that, if the dissipation is strong enough, the structure of electron bunches is dynamically stable in a range of times exceeding several characteristic times of their formation.

Download Full-text

Design of a dual-frequency high-power microwave generator

Laser and Particle Beams ◽

10.1017/s0263034611000590 ◽

2011 ◽

Vol 29 (4) ◽

pp. 479-485 ◽

Cited By ~ 14

Author(s):

Juntao He ◽

Yibing Cao ◽

Jiande Zhang ◽

Ting Wang ◽

Junpu Ling

Keyword(s):

High Power ◽

Microwave Power ◽

Wave Interaction ◽

Total Power ◽

Dual Frequency ◽

High Power Microwave ◽

Beam Wave ◽

Interaction Efficiency ◽

Beam Wave Interaction ◽

Power Microwave

AbstractA new direction for high-power microwave (HPM) development is to investigate devices capable of producing HPMs with a complicated spectrum. In recent years, some HPM sources with two stable and separate frequencies have been investigated theoretically and experimentally. However, many short-comings still exist in these devices. Especially, the beam-wave interaction efficiency and the output microwave power are low in such devices. This paper proposes a novel dual-frequency HPM generator based on transition radiation. In the device, the electromagnetic fields are localized near the resonator cavities in the form of standing waves, and thus the interference between the different HPM components with different frequencies is weak. Compared with the existing dual-frequency devices, the new structure allows high beam-wave interaction efficiency and high output microwave power. As indicated in particle-in-cell simulation, with an electron beam of 500 kV voltage and 15.0 kA current guided by a magnetic field of 0.8 Tesla, an average power of 1.60 GW with a total power conversion efficiency of 21.3% is obtained, and the frequencies are 1.53 GHz and 3.29 GHz, respectively. Power level between two HPMs is comparable. The simulation results verify the feasibility of the dual-frequency HPM generator.

Download Full-text