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

钻石光源(Diamond)是一种粒子加速器，位于牛津郡哈威尔科学与创新园区。电子被推进到接近光速的速度，并被注入存储环。电子束被聚焦，并通过在环周围以重复图案排列的一系列磁铁保持在其轨道上。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。发射的辐射被偏转到光子光束线，并被引导到几个实验站，在那里用于分子的衍射、光谱和三维成像。为了保证实验的质量，光束沿稳定的路径运行是至关重要的。电子束偏离理想轨道的偏差是由束流位置监测器测量的，必须通过校正磁铁的主动控制来衰减。钻石存储环中的快速轨道反馈(FOFB)确保了束流线上所有实验的束流位置的稳定性。现有的控制器在环周围分布的24个通用中央处理单元(CPU)中实现。在这种方法中，多输入多输出控制问题是通过与一个条件伪逆轨道响应矩阵相乘，然后是一个内模控制器(IMC)来解决的。这种情况下的计算可以通过将矩阵分成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，这些修改和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(执行器)。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。这些理想的功能超出了当前实施的能力。该项目将研究快速轨道控制的未来架构(包括分析和实施)：更先进的控制算法，如逐个模式控制和模型预测控制，以及必要的新处理节点的原型，这将使计算完全集中。总而言之，该项目将建立快速轨道控制的方法和实现，以适应钻石-II机器上可预见的挑战，同时承诺在实施后已有更好的轨道控制。该项目属于EPSRC工程研究领域，并与钻石光源有限公司合作。

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.