I13-1-Coherence
Controls
Detectors
Insertion Devices
Magnets
|
Open Access
Abstract: Synchrotron radiation provides a number of outstanding features
that are highly valuable for X-ray imaging and tomography. One of
them is the partial coherence of the radiation, which is explored at
the X-ray Imaging and Coherence beamline (I13) at Diamond Light
Source. The variety of methods employed at the beamline offer imaging with the highest quality. We discuss the benefi t of imaging with
coherent radiation and describe methods and applications available at Diamond’s I13 beamline.
|
Sep 2017
|
|
Controls
|
Abstract: This paper considers the problem of designing an optimal controller for the linear static system associated with electron beam stabilisation systems in synchrotrons. The relationship between the actuators and sensors used for electron beam control in synchrotrons is modelled as a static response matrix which is typically ill-conditioned. Singular Value Decomposition (SVD) is commonly used to invert the response matrix and modes associated with small singular values are either discarded or filtered. In this paper, a robust control approach is used to determine the optimal static controller to the perturbed system. It is demonstrated how this approach compares to the use of Tikhonov regularisation for an inverse-based controller. A detailed example from the Diamond Light Source synchrotron is presented, applying both the inverse-based method and the robust control approach to stabilise electron beam motion.
|
Jul 2017
|
|
Controls
|
W.
Rogers
,
M. G.
Abbott
,
K. A. R.
Baker
,
N.
Battam
,
M. J.
Furseman
,
I. J.
Gillingham
,
P.
Hamadyk
,
M. T.
Heron
,
D. G.
Hickin
,
S.
Lay
,
I. P. S.
Martin
,
A.
Rose
Open Access
Abstract: Upgrading one Double Bend Achromat cell to a Double Double Bend Achromat (DDBA) cell in the Diamond Light Source storage ring necessitated a broad range of changes to the overall control system. These changes covered developments to the interface layer of the controls system to incorporate changes to the underlying instrumentation, associated development of user interface, changes to real-time feedback and feed-forward processes and to the online accelerator model. Given the pressures to minimise the shutdown length, the control system developments were optimised for time effective installation and commissioning. This paper outlines the control system developments for DDBA, the management process and lessons learnt from this process.
|
May 2017
|
|
Controls
|
Abstract: Haptic interfaces have become common in consumer electronics. They enable easy interaction and information entry without the use of a mouse or keyboard. The work presented here illustrates the application of a haptic interface to crystallization screening in order to provide a natural means for visualizing and selecting results. By linking this to a cloud-based database and web-based application program interface, the same application shifts the approach from `point and click' to `touch and share', where results can be selected, annotated and discussed collaboratively. In the crystallographic application, given a suitable crystallization plate, beamline and robotic end effector, the resulting information can be used to close the loop between screening and X-ray analysis, allowing a direct and efficient `screen to beam' approach. The application is not limited to the area of crystallization screening; `touch and share' can be used by any information-rich scientific analysis and geographically distributed collaboration.
|
Dec 2016
|
|
Controls
|
Abstract: By accelerating electrons to relativistic speeds, synchrotrons generate extremely intense and narrow beams of electromagnetic light that are used for academic research and commercial development across a range of scientific disciplines. In order to achieve optimum performance, the stability of the electron beam is a crucial parameter for synchrotrons and is achieved by a beam stabilisation system that is used to control the location of the electron beam and minimise any instability of the electron beam caused by external disturbances. Slew rate limits are common nonlinearities encountered with the actuators in synchrotron feedback systems which can impose significant limitations on the robustness and the performance of the control system. This paper describes an Internal Model Control (IMC) based anti-windup synthesis using an algebraic Riccati equation for a discrete-time control system to compensate against the performance deterioration in the presence of rate constraints. An Integral Quadratic Constraint (IQC) framework is used to analyse the robust stability of the anti-windup augmented closed loop system in the presence of norm-bounded uncertainty. The anti-windup augmented controller is implemented at Diamond Light Source, the UK’s national synchrotron facility and improvements in robustness and performance were achieved with respect to the use of no anti-windup compensation.
|
May 2016
|
|
Accelerator Physics
Controls
Detectors
Theoretical Physics
|
Abstract: The Diamond Light Source is investigating several paths for a possible machine upgrade to Diamond II. The exercise is driven by a joint assessment of the science capabilities opened by a very low emittance ring and the machine design that will underpin them. The consultation is made on a beamline-by-beamline basis and has highlighted a significant preference for lattices that
combine both a low emittance and large capacity for IDs.
|
May 2016
|
|
Controls
|
Abstract: Accurate knowledge of the longitudinal profile of the bunch is important in the context of linear colliders, wake-field accelerators and for the next generation of light sources. As a result the non-destructive, single-shot evaluation of the profile is one of the challenging problems which can be addressed via spectral analysis of coherent radiation generated by a charged particle bunch. To reconstruct the bunch profile from the spectrum the phase retrieval problem has to be solved. Frequently applied methods, e.g. minimal phase retrieval or other iterative algorithms, are reliable if the Blaschke phase contribution is negligible. This is neither known a priori nor can it be assumed to apply to an arbitrary bunch profile. We present a novel approach which gives reproducible, most-probable and stable reconstructions for bunch profiles that would otherwise remain unresolved by the existing techniques. The algorithm proposed uses the output of Kramers-Kronig minimum phase as both initial and boundary conditions, providing a unique solution. To assure a converging solution, new conditions linked to the independently known experimental data such as beam charge were introduced.
|
May 2016
|
|
Controls
Detectors
|
Abstract: High frequency beam motion has been identified as a source of noise in infrared beamlines in a number of synchrotron light sources. Diamond is a third generation synchrotron light source with storage ring current maintained by two superconducting CESR-B cavities powered by IOT-driven RF amplifiers. In our case, undesirable beam motion in the kilohertz range is predominantly driven by spectral content in the voltage across the IOTs arising from the switched mode nature of the high voltage power supply. Spectral noise on the amplifiers and beam has been identified and characterised and efforts to eliminate this noise are described. Care has been taken to maintain the overall stability of the RF at Diamond and tests have been carried out on an infrared beamline to investigate the degree to which beam noise impacts beamline operation in its different operating configurations.
|
Dec 2015
|
|
Controls
|
Open Access
Abstract: The design and implementation of a compact and portable sample alignment system suitable for use at both synchrotron and free-electron laser (FEL) sources and its performance are described. The system provides the ability to quickly and reliably deliver large numbers of samples using the minimum amount of sample possible, through positioning of fixed target arrays into the X-ray beam. The combination of high-precision stages, high-quality sample viewing, a fast controller and a software layer overcome many of the challenges associated with sample alignment. A straightforward interface that minimizes setup and sample changeover time as well as simplifying communication with the stages during the experiment is also described, together with an intuitive naming convention for defining, tracking and locating sample positions. The setup allows the precise delivery of samples in predefined locations to a specific position in space and time, reliably and simply.
|
Nov 2015
|
|
Controls
|
Abstract: Since commissioning, Diamond Light Source has used
the Extensible Display Manager (EDM) to provide a GUI
to its EPICS-based control system. As Linux moves away
from X-Windows the future of EDM is uncertain, leading
to the evaluation of Control System Studio (CS-Studio) as a
replacement. Diamond has a user base accustomed to the
interface provided by EDM and an infrastructure designed to
launch the multiple windows associated with it. CS-Studio
has been adapted to provide an interface that is similar to
EDM’s while keeping the new features of CS-Studio available.
This will allow as simple as possible a transition to
be made to using CS-Studio as Diamond’s user interface to
EPICS. It further opens up the possibility of integrating the
control system user interface with those in the Eclipse based
GDA and DAWN tools which are used for data acquisition
and data analysis at Diamond.
|
Oct 2015
|
|
