New kick-and-cancel injection system for Diamond-II

One of the most important improvements that will be made during the Diamond-II upgrade, is how fresh electrons are added to the storage ring – the heart of the machine that produces the powerful X-ray beams used by researchers. The injection process can have a big impact. The smoother and more stable the injection, the more consistent and reliable the X-ray beam is for scientists carrying out experiments.The upgraded machine is designed to produce a more tightly focused and stable beam, and achieving this performance depends on an injection system that is highly reliable and causes minimal disturbance.

To meet this challenge, Diamond’s accelerator physicists, engineering teams and industry partners have developed an approach known as kick-and-cancel injection. This is a major step forward in beam stability.

At Diamond, electrons circulate around the storage ring in tightly packed groups known as “bunches”. To maintain beam intensity, they are regularly topped up by adding small amounts of charge.

In the current system, all the circulating electron bunches experience a small disturbance during top-up. While this effect is brief, it can cause tiny dips in brightness that are noticeable in especially sensitive experiments. The new kick-and-cancel system changes this.

Instead of disturbing every bunch, it precisely targets only the one that needs topping up. A very fast electromagnetic pulse gently nudges the target electron bunch into position. A second pulse then quickly cancels out that motion, restoring perfect alignment and allowing the added charge to be captured.

The result is that the other circulating bunches remain undisturbed, keeping the beam more stable and consistent for users. This improvement will be particularly valuable for time-sensitive experiments and advanced operating modes, where beam stability is critical.

Delivering this level of precision requires extremely fast and powerful equipment. The system uses specialised devices called stripline kickers. These components deliver ultra-fast electrical pulses to steer individual electron bunches with exceptional accuracy.

“The new kick-and-cancel injection scheme developed for Diamond-II builds on previous methods using fast stripline kickers. By placing the stored bunch back on-axis after a few turns, harmful wake-fields are prevented from building up that would otherwise cause the electrons to become unstable and be lost from the ring. The switch to using few nanosecond stripline kickers rather than the existing relatively long-pulse dipole kickers enables us to target only the individual electron bunches that require topping-up,” said Ian Martin, Head of Accelerator Physics Group.

To make this possible, Diamond teams worked closely across accelerator physics, engineering, vacuum systems, power supplies and controls. We also partnered with industry, including Kentech Instruments, to develop the high-voltage power supplies capable of producing sub-3-nanosecond pulses.

Key innovations include ultra-fast, high-voltage pulsers; advanced prototype stripline kickers with highly uniform electromagnetic fields; and new injection magnet designs to improve stability and reduce jitter.

First proof-of-principle tests.

Designing and testing this equipment required detailed simulations, careful engineering, and close collaboration across multiple technical disciplines. 

Prototype components have now been tested directly in the storage ring under real operating conditions. The results were highly encouraging as the system met all stability and performance requirements.  

The double-pulse “kick-and-cancel” effect was successfully demonstrated with the measured beam behaviour matching predictions and the high-charge electron bunches remaining stable. These proof-of-principle tests confirmed that the approach works as intended and can deliver the improvements needed for Diamond-II. 

Next steps: moving toward full deployment 

With the concept validated, the focus now shifts to finalising production designs and preparing the system for full deployment as part of the Diamond-II upgrade. 

Further optimisation work will refine timing and pulse shaping to ensure the system operates with maximum precision and reliability. 

Because the kick-and-cancel approach is innovative, it has also attracted interest from other leading synchrotron facilities. Diamond recently hosted experts from the European Synchrotron Radiation Facility and the Swiss Light Source, who are keen to collaborate and learn from the work being carried out here. 

For more information on the kick-and-cancel injection scheme you can read the article published in Physical Review Accelerators and Beams. 

Kick-and-cancel injection scheme for the Diamond-II storage ring