带状电子束的空间电荷场

Space-charge field of sheet electron beam

利用理论分析和数值计算的方法研究了矩形波导内均匀电流密度的带状电子束模型的空间电荷场,给出了该带状电子束模型的空间电荷场的解析表达式,并研究了空间电荷场随带状电子束的几何参数和物理参数的变化规律。研究表明:在不改变电流密度的前提下,更宽的电子束可以传输更强的束流,而空间电荷场并不随束宽度的增大而增大,但是增加电子束厚度会使空间电荷场显著增强,从而不利于高流强电子束的传输;对于相同电流的带状电子束,保持电子束厚度不变,增大电子束宽度,相应地降低电流密度是降低空间电荷场的一个很好的途径,而保持电子束的宽度不变,增大束厚度,相应地降低电流密度只会使沿着电子束截面宽度方向的电场减小,而沿着电子束截面厚度方向的电场基本不变;对于相同电流和电流密度的带状电子束,更宽、更薄的电子束横截面尺寸能使沿着电子束截面宽度方向的电场降到更低,而沿着电子束截面厚度方向的电场只是略有减小。

The space-charge field characteristics of a uniform sheet electron beam in a rectangular waveguide have been investigated theoretically and numerically. The expressions of the space-charge field components are derived, and numerically calculated for different dimensions and current densities. Results show that, for a constant current density of the sheet beam, the sheet beam could propagate with a larger current when the beam cross-section is wider. In addition, the space-charge field of the sheet electron beam with a constant current density will not be enhanced while increasing the width of the beam, but will be enhanced while increasing the thickness of the beam. However, only the electric field component along the direction of the long side of the beam cross-section is weakened by increasing the thickness of the beam, and only the electric field component along the direction of the short side of the beam cross-section could be weakened by increasing the aspect ratio of the sheet electron beam with constant current and current density.