磁场对球头阴极二极管特性的影响
Influence of magnetic field on I-V relations of spherical cathode diode
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摘要: 采用全电磁PIC粒子模拟方法研究了磁场对球头阴极二极管物理特性的影响。结果表明外加磁场主要是通过对二极管束流轨迹的改变来影响二极管的物理特性。由于外加磁场将约束其产生电子束的发散，结果使其空间电荷限制电流减小，其值在无外加磁场并且自磁场可以忽略时的空间电荷限制电流值的0.5~1倍范围内。当外加磁场足够强时，束流轨迹主要受外加磁场控制，二极管产生的电子束既不箍缩也不发散。强外加磁场条件下的空间电荷限制电流近似为无外加磁场时的一半；在无外加磁场条件下，在阳极处的束流半径随二极管电压电流的增大而减小，空间电荷限制电流增强因子随束流半径的减小而减小，随二极管电压电流增大而减小。这一系列结果是在二极管电流小于其自箍缩临界电流条件下得到的。Abstract: Magnetic field affects strongly characteristics of spherical cathode diode. The numerical research shows that the effect of magnetic field (include self-magnetic field and external magnetic field) on diode takes place via varying the tracks of electron beam. The space charge limited current decreases as external applied magnetic field increases. With intense enough external applied magnetic field, the space charge limited current of diode is about half of the current without external applied magnetic field. In conditions without external applied magnetic field, radius of beam at anode surface and enhancement factor of space charge limited current both tend to decrease with increasing diode current.
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Key words:
- diode /
- space charge limited current /
- intense relatiristic electron beams
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