Cyclotron

回旋加速器

The cyclotron was one of the earliest types of particle accelerators, and is still used as the first stage of some large multi-stage particle accelerators. It makes use of the magnetic force on a moving charge to bend moving charges into a semicircular path between accelerations by an applied electric field. The applied electric field accelerates electrons between the "dees" of the magnetic field region. The field is reversed at the cyclotron frequency to accelerate the electrons back across the gap.

When the cyclotron principle is used to accelerate electrons, it has been historically called a betatron. The cyclotron principle as applied to electrons is illustrated below.

当回旋加速器原理用于加速电子时，历史上被称为电子感应加速器。电子感应加速器的原理如下面所示。

Note: these illustrations are grossly simplified for demonstration of the cyclotron principle. In current practice sine waves are used for the acceleration and the "dees" are resonant cavities favoring one frequency. The magnetic fields are typically altered to keep the acceleration condition optimized, even when speeds become high enough that relativistic corrections are necessary.

注意：这些示意图是为了说明回旋加速器的基本原理而大大简化的。在实际应用中，使用正弦波作为加速信号，‘德’形腔体倾向于某一特定频率。磁场均通常被调整以保持加速条件的优化，即使在速度足够高，需要考虑相对论修正的情况下也是如此。

回旋加速器是最早的一种粒子加速器，至今仍被用作一些大型多阶段粒子加速器的第一阶段。它利用磁场对运动电荷的作用力，使运动电荷在电场作用下弯曲成半圆形路径。所施加的电场加速电子通过回旋加速器磁场区域中的‘德’。磁场在回旋频率下反转，以将电子再次加速通过间隙。

Cyclotron Frequency

回旋频率

A moving charge in a cyclotron will move in a circular path under the influence of a constant magnetic field. If the time to complete one orbit is calculated:

在回旋加速器中，一个运动的电荷在恒定磁场的作用下将沿圆周路径运动。若计算完成一个轨道所需的时间：

it is found that the period is independent of the radius. Therefore if a square wave is applied at angular frequency qB/m, the charge will spiral outward, increasing in speed.

发现周期与半径无关。因此，如果在角频率为 qB/m 时施加方波，电荷将向外螺旋运动，速度逐渐增加。

When a square wave of angular frequency

当一个角频率为的方波

is applied between the two sides of the magnetic poles, the charge will be boosted again at just the right time to accelerate it across the gap. Thus the constant cyclotron frequency can continue to accelerate the charge (so long as it is not relativistic).

当磁场施加在磁极两侧时，电荷将在恰好的时间被再次加速，使其穿越间隙。因此，恒定的回旋频率可以继续加速电荷（只要非相对论性）。