This paper describes a method for reducing the energy of the cyclotron motion for charged particles in coherent beams using a nonadiabatic magnetic field. For the purpose of reducing the cyclotron motion, a local magnetic field reduction of the main guiding field should be situated in the region of the descending phase of the beam oscillation. The required local magnetic field depression can be produced with a soft iron ring or with a magnet coil. The nonadiabatic element can be positioned on the descending part of any period of the beam oscillation where the beam still remains sufficiently coherent. The effect of reducing the cyclotron motion with such nonadiabatic magnetic field is independent of the electric field of the cathode-anode gap and seems to be a universal method for the cyclotron motion control in coherent beams. Therefore, it can be used for reducing the cyclotron motion of electron beams produced with different kinds of guns with different perveances and sizes. For instance, the method is capable of creating ripple-free, laminar beams even for magneto-immersed guns positioned in a magnetic field of only a few hundred Gs and with a cathode emission current density exceeding $30\mathrm{A}/{\mathrm{cm}}^2$. It can also be applied for guns producing tubular beams, as demonstrated by our simulations. The results of computer simulations are presented, which demonstrate the capability of effective cyclotron motion control with nonadiabatic magnetic field.

中文翻译：

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用非绝热磁场控制电子束回旋运动的方法

本文介绍了一种使用非绝热磁场降低相干束中带电粒子回旋加速器运动能量的方法。为了减小回旋加速器的运动，应将主引导场的局部磁场减小置于射束振荡的下降阶段的区域中。所需的局部磁场抑制可以通过软铁环或电磁线圈产生。非绝热元件可以位于光束振荡的任何周期的下降部分，在该阶段，光束仍然保持足够的相干性。利用这种非绝热磁场来降低回旋加速器运动的效果与阴极-阳极间隙的电场无关，并且似乎是相干光束中回旋加速器运动控制的通用方法。因此，它可用于减少由不同类型和不同尺寸的电子枪产生的电子束的回旋运动。例如，该方法甚至能够为定位在仅几百个Gs的磁场中且阴极发射电流密度超过100％的磁浸枪产生无波纹的层流光束。$30\mathrm{一种}/{\mathrm{厘米}}^2$。正如我们的模拟所证明的，它也可以应用于产生管状光束的枪支。给出了计算机仿真的结果，这些结果证明了具有非绝热磁场的有效回旋加速器运动控制的能力。