Yang Zhonghai

The kinetic theory of the electron cyclotron resonance maser with space charge effect taken into consideration

The kinetic theory of the electron cyclotron resonance maser is given in this paper with the space charge effect and non-resonance cyclotron harmonics taken into consideration. The dispersion equations have been calculated using a digital computer and the influence of these factors are discussed in detail.

Gyrotron with quasi-optical cavity of special configuration†

Abstract A quasi-optical cavity of special configuration suitable for use in a high-power gyrotron operating at short millimetre and submillimetre wavelength has been developed. A gyrotron using this new type of cavity is under development. Both the linear and non-linear analyses are worked out. Digital calculation predicts efficiency of 37% at V 0 = 50 kV.

Application and validation of the TWTCAD integrated framework

TWTCAD integrated framework is a suite of helix TWT design software. It is composed of five software and interface specification between software. It includes: FemGun, a 2D gun software based on finite element method; HelixCT, a 2D helix circuit cold test software; BWI, 1D & 2D & 3D large signal software; MDCollector, a 2D multistage depressed collector design software; fPPM, magnet design software. It has been validated against some TWTs and applied in microwave tube industry.

Dispersion Analysis of helical corrugation waveguide for Gyro-TWT and Gyro-BWO

The paper puts forward a simple method of solving the coupled coefficient and the dispersion equation of the backward wave in the helical corrugation waveguide gyro-BWO. And using the VBA macro in the software CST, two taper parts and a regular part helical waveguide is founded. A simulation method is used to analysis the dispersion curve.

Three-dimensional nonlinear theory of travelling wave tubes and simulation

A three-dimensional (3D) nonlinear theory of travelling wave tubes (TWTs) is developed, which includes a fundamental radio frequency (RF) and harmonics. When the instantaneous bandwidth exceeds an octave, the harmonic is generated and the mutual coupling between the harmonic and the fundamental RF can be observed in TWTs due to nonlinear interaction between the electron beam and the RF. At low frequencies the harmonic has an obvious effect. Based upon Tiens disc model, a plastic 3D super-particle model is proposed to improve the nonlinear analysis of TWTs. Numerical results employing a periodic magnetic focusing field are presented.

First experiment of gyrotron tube with quasi-optical cavity of special configuration

A new kind of quasi-optical cavity—Axisymmetrical Quasi-Optical Cavity of Oblique Rotation (AQCOR) and the new scheme for quasi-optical gyrotron with AQCOR had been proposed in [1], and the experimental tube was built in our institute. Now the initial test results of the tube are reported in this paper.

Diagnosis of Hydrogen Plasma in a Miniature Penning Ion Source by Double Probes

Parameters of hydrogen plasma in a miniature Penning discharge ion source, including the electron temperature and the electron density, were measured by using double probes. The results indicate that the electron density increases and the electron temperature decreases with the increase in gas pressure and the discharge current. The electron temperature is about 5–9 eV and the electron density is 6.0×1013 ~ 1.2 × 1014 m−3 while the discharge current is in a range of 50 ~ 120 μA.

A Correction Method for Analysis of Inhomogenously-Loaded Helical Slow-Wave Structures

In the theoretical analysis of cold-test characteristics for inhomogenenously-loaded helical slow-wave structures, a correction method is suggested to compensate the field non-uniformity during one helix period, in which an effective helix outer radius is adopted instead of the real helix outer radius. The theoretical predictions with and without correction are both compared with MAFIA simulation results and the illustrations have proved the validity of the correction method

How to get a large-amplitude plasma wake wave

The large-amplitude nonlinear plasma wake wave driven by ultra-relativistic electron beams of different lengths and densities is studied using the analytical theory of the ultra-relativistic fluid equations. The approximate analytical solution for the wake wave is obtained and how to obtain large-amplitude wake waves is discussed.

Higher Harmonics in Free Electron Laser with a Two-Wavenumber Plane Wiggler Magnetic Field

The higher harmonics of the free electron laser (FEL) with a two-wavenumber plane wiggler magnetic field, which may induce a lot of higher harmonics, are investigated. Using a two-wavenumber wiggler comprised of two separate periodicities, kw and kw + Δk, numerical simulations show that the higher harmonic may be amplified and the first harmonic may be suppressed in this kind of FEL with an optimized parameter Δk. The coupling coefficient and gain coefficient in low-gain regime of the harmonic are also obtained.