Fast, high precision, low cost position diagnostic for free electron lasers

Lead Research Organisation: Royal Holloway, University of London
Department Name: Physics


Beam instrumentation are the eyes and ears of an operator delivering an electron beam to a free electron laser (FEL). In particular, position diagnostics help optimising and later reproducing the "golden" path for electrons throughout the FEL that ensures the best quality and brightest burst of X-ray light at the FEL's output. It is important to sustain the best possible conditions for experiments making use of the X-rays, which can include a wide variety of investigations, in subjects ranging from archeology to bio-science, from security to nanofabrication.

It is a never ending quest for scientists and engineers designing FELs and driving them linear accelerators (linacs) delivering the electrons for lasing, to provide better performance at a lower cost. Inevitably, new ideas are in demand. Our project is part of this quest: we have an idea on how to replace older beam position diagnostics with a newer, higher resolution, faster type without inflating the cost. This new idea is waveguide beam position monitors (WGBPM).

WGBPM models have demonstrated their basic functionality in our laboratory, but significant effort is still needed to convert this work into a demonstrator prototype that can be installed in a real life electron accelerator. Therefore, we will focus on developing the hardware and methods for a real life proof-of-principle experiment. This will involve multiple 3D electromagnetic simulations to optimise the device and predict its output, work with mechanical engineers to ensure the device can be easily manufactured and all the complex demands of an accelerator machine are met.

The signals produced by WGBPMs are very short electric pulses, which will need to be turned into useful information. We will design analogue electronics which will help preparing these pulses for crossing the boundary between the analogue and digital worlds and also work on algorithms that extract the position information from the digitised signals.

We are then hoping to proceed to a critical test, installing the prototype in a real life accelerator exposing it to a beam of electrons. We want to see that the device can indeed sense the beam's position the way it is supposed to, and confirm our expectations on the output it gives and the precision it can sense the beam position with.

By the end of this project we would like to be able to start "knowledge exchange": team up with a company and work towards making waveguide beam position monitors available to scientists worldwide in a form of a complete, commercially available product.


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