"When a beam of fast, high energy electrons are injected into an undulating magnetic field (often called a 'wiggler'), they are forced to oscillate perpendicular to their direction of propagation and to emit light at the electron oscillation frequency. As this mixture of electrons and light propagates along the wiggler, the electrons begin to 'bunch' at the same wavelength as the light and act in unison to generate high brightness coherent light. When this happens it is called a Free Electron Laser (FEL). When the electrons are accelerated to speeds just below the speed of light, the electrons can emit X-ray light. This has a very short wavelength and can be used to make images of very small objects such as atoms. If the X-rays can be made into very short pulses, they can also take images of atoms without blurring - just like using the flash on a camera in a dark room.
Most computer codes that simulate this FEL interaction make simplifications in the process which allows faster computation times. However, these simplifications mean that some information about the process is lost. This lost information is necessary if one wants to simulate e.g. very short light pulse generation. This proposal includes the lost information in a computer simulation code 'PUFFIN' which allows new methods to be investigated to improve the quality of the light emitted by the FEL. In addition, we will connect up PUFFIN with other simulation codes that allow the full FEL to be modelled from the start of the electron acceleration through to their exit at the end of the FEL. These 'start-to-end' simulations are important as they can allow different electron accelerators to be tested as drivers of the FEL, and can model their different characteristics. One such accelerator of current interest is the plasma accelerator which can be much smaller than current Radio-Frequency accelerators used to drive FELs. Use of plasma accelerators would significantly reduce the cost of FELs and make then more accessible to a wider group of scientists. PUFFIN is useful as it can model electron beams from plasma accelerators much better than other simulation codes.
Keeping the extra information contained in the PUFFIN simulations, and linking it up with other simulation codes, results in a powerful FEL simulator that can model effects such as very short pulse generation and plasma accelerator drivers of FELs. This ability opens up many new areas for research to improve the light output from FELs.
With these improvements would come the ability to investigate new areas of science that have until now been closed to us. These areas differ hugely, from observing how viruses and potential new drugs penetrate the membranes of living cells to creating conditions in the laboratory similar to those at the centre of Jupiter and Saturn.
The improvements to simulating the FEL process using PUFFIN have the potential to have a real and large impact on such fundamental scientific knowledge. Furthermore, this fundamental knowledge can play a crucial role in developing new products and processes that will help economies, society and the environment."