Advanced Control Systems for Fast-Orbit Feedback (FOFB) of the Electron Beam in the Diamond Synchrotron

钻石光源（Diamond）是位于牛津郡哈维尔科学与创新园区的粒子加速器。电子以接近光速的速度被推进并注入到存储环中。电子束被聚焦并保持在它的轨道路径上，使用一系列围绕环以重复模式排列的磁铁。当电子以相对论速度绕环运动时，它们会发出一种特殊形式的辐射，称为同步加速器光。发射的辐射被偏转成光子束线，并被引导到几个实验站，在那里它被用于衍射、光谱学和分子的三维成像。为了保证实验的质量，光束的稳定路径是至关重要的。电子束与理想轨道的偏差是用电子束位置监测器测量的，必须用校正磁体的主动控制来衰减。钻石存储环中的快速轨道反馈（FOFB）保证了光束线上所有实验的光束位置的稳定性。现有的控制器是由分布在环上的24个通用中央处理器（cpu）实现的。在该方法中，多输入-多输出控制问题是通过带条件的伪逆轨道响应矩阵的乘法和内模控制器（IMC）来解决的。在这种情况下，计算可以通过将矩阵切成24个部分来分配给24个cpu。这种方法正受到现有修改和未来升级的挑战，这些升级可能会引入具有均匀动力学（不同结构或不同容器材料的磁铁）的校正器（致动器）。此外，处理对执行器范围或速率的限制，以及对某些监视器施加特定限制的能力，将是有益的。这些理想的特性超出了当前实现的能力。该项目将研究快速轨道控制的未来架构（包括分析和实现）：更先进的控制算法，如逐模控制和模型预测控制，以及必要的新处理节点的原型，这将使完全集中计算成为可能。总之，该项目将确定快速轨道控制的方法和实施方法，以适应金刚石- ii型机器上可预见的挑战，同时承诺在实施后已经有更好的轨道控制。该项目属于EPSRC工程研究领域，与Diamond光源有限公司合作。

The Diamond Light Source (Diamond) is a particle accelerator located at the Harwell Science and Innovation Campus in Oxfordshire. Electrons are propelled near the speed of light and injected into the storage ring. The electron beam is focused and kept in its orbital path using a series of magnets arranged in a repeating pattern around the ring. While the electrons travel around the ring at relativistic speeds, they emit a particular form of radiation called synchrotron light. The emitted radiation is deflected into photon beamlines and guided into several experimental stations where it is used for diffraction, spectroscopy and three-dimensional imaging of molecules.In order to guarantee the quality of the experiments, it is of utmost importance that the beam follows a stable path. The deviations of the electron beam from its ideal orbit are measured using beam position monitors and must be attenuated using active control of the corrector magnets.The Fast Orbit Feedback (FOFB) in the Diamond storage ring ensures stability of the beam position for all the experiments on the beamlines. The existing controller is implemented in 24 general purpose Central Processing Units (CPUs) distributed around the ring. In this approach, the Multi-Input-Multi-Output control problem is address using multiplication with a conditioned pseudo inverse orbit response matrix followed by an Internal Model Controller (IMC). The calculations in this case can be distributed to 24 CPUs by slicing the matrix into 24 parts.This approach is being challenged by existing modifications and future upgrades which may introduce correctors (actuators) with homogeneous dynamics (magnets of different construction or over different vessel material). Furthermore, it would be beneficial to deal with constraints on actuators range or rate, as well as the ability to put particular constrains on certain monitors. These desirable features are beyond the abilities of the current implementation.This project will investigate a future architecture (both analytically and by implementation) of fast orbit control: more advanced control algorithms like mode-by-mode control and model predictive control, as well as a prototype of the necessary new processing node, which will enable fully centralised calculations.In summary, the project will establish the methods and an implementation of fast orbit control required to adapt to foreseeable challenges on a Diamond-II machine, while at the same time promising better orbit control already after implementation.This project falls within the EPSRC Engineering research area and collaborates with Diamond Light Source Ltd.