In electron beams where space charge plays an important role in the beam transport, the beams’ transverse and longitudinal properties will become coupled. One example of this is the transverse–longitudinal correlation produced in a current-modulated beam generated in a DC electron gun, formed through the competition between the time-dependent radial space charge force and the time-independent radial focusing force. This correlation will cause both the slice radius and divergence of the beam extracted from the gun to depend on the slice current. Here we consider the transport of such a beam in a linearly tapered solenoid focusing channel. Transport performance was generally improved with longer taper lengths, minimal initial correlation between slice divergence and slice current, and moderate degrees of initial correlation between initial slice radius and slice current. Performance was also generally improved with lower slice emittances, although surprisingly transport was improved by slightly increasing the assumed slice emittance in certain limited circumstances.

中文翻译：

---

在线性锥形螺线管通道中传输具有电流相关初始条件的强光束

在空间电荷在电子束传输中起重要作用的电子束中，电子束的横向和纵向特性将耦合。一个例子是在直流电子枪中产生的电流调制束中产生的横向-纵向相关性，它是由时间相关的径向空间电荷力和时间相关的径向聚焦力之间的竞争形成的。这种相关性将导致切片半径和从喷枪中提取的光束的发散都取决于切片电流。在这里，我们考虑在线性锥形螺线管聚焦通道中传输此类光束。更长的锥度长度，最小限度的条带散度和条带电流之间的初始相关性通常会改善运输性能 初始切片半径和切片电流之间的中等程度的初始相关性。虽然在某些有限的情况下，通过略微增加假定的切片发射率，出乎意料的改善了运输性能，但通常通过降低切片发射率也可以改善性能。