Formation of a laminar electron flow for 300 GHz high-power pulsed gyrotron

Abstract

This paper describes the design of a triode magnetron injection gun for use in a 200 kW, 300 GHz gyrotron. As power and frequency increase, the performance of the gyrotron becomes quite sensitive to the quality of the electron beam. Formation of a laminar electron flow is essential for the realization of a high quality beam with a small velocity spread. In this study, a new method is developed for a quantitative evaluation of the laminarity and is applied to optimize the electrode design. The laminarity depends not only on conventional design parameters such as the cathode slant angle, but also on the spatial distribution of the electric field along the beam trajectory. In the optimized design, the velocity pitch factors, α, larger than 1.2 are obtained at 65 kV, 10 A with spreads, Δα, less than 5%.

Application of a potential profile for controlling the beam laminarity in a magnetron injection gun

“…3(b)). As shown in the figure, α-values of electrons on the outer trajectory are always smaller than those of inner ones throughout the K-A region [5]. Here, it is found that the differences in α-values are produced by the differences in the parallel velocities (β // ).…”

Analysis of oscillation characteristics and optimal conditions for high power operation of Gyrotron FU CW GIII

“…The electrode configurations were optimized by forming laminar electron trajectories, which resulted in a substantial reduction in the spread, Da, of the pitch factor (a) of the electron beam at the cavity entrance. 9,10 As a result, Da decreased from more than 30% in Gyrotron FU CW GII to 7% in Gyrotron FU CW GIII. 2,7 An inner mode converter composed of a Vlasov launcher 11 tunable and rotatable.…”

Conformal Cross-Flow Axis-Encircling Electron Beam for Driving THz Harmonic Gyrotron

“…The electrons are emitted from cathode and helically travel around the z-axis toward the cavity region. In [14], two Busch's theorem [12]- [15] is applied to estimate the parameters of a specified electron trajectory, and given as   …”