| Popis: |
Low-noise CFA operation regimes have been observed experimentally, and computationally modeled. Access to low-noise operation is observed for low magnetic field and high cathode emission current. The 2 1/2 -D PIC code MASK has successfully modeled CFA operational parameters such as anode voltage and current, and output RF gain. It has also demonstrated the ability to model signal-to-noise values for both high and low noise CFA operation. The low-noise simulation results are dependent on the number of macro-particles and the numerical discretization noise associated with density fluctuations resulting from a finite number of simulation macro-particles. Using suitably large number of macro-particles, we have used MASK including a multi-conductor transmission line (MTL) circuit model to model a particular CPI crossed-field amplifier SFD-266/VXS-1925. The MTL model reproduces the observed circuit dispersion curve closely. The goal of this study is the modeling of CFA noise as function of cathode thermionic emission and magnetic field, and the comparison of the simulation results with observed noise levels. |
