Abstract
The first observation of lasing in an infra-red free electron laser (IR-FEL) at the Raja Ramanna Centre for Advanced Technology has been reported recently with a measured power output, i.e. \({\sim }10^{5}\) times higher than the expected spontaneous radiation power for the electron beam parameters used in the experiment. IR-FEL design simulations, however, estimate a power gain of \(10^{7}\) which is three orders of magnitude higher than the experimentally achieved value. To understand this difference between the measured and the expected power output from the IR-FEL, the electron beam used in the experiments has been characterised and FEL simulations have been repeated after considering the measured electron beam parameters. A reasonably good agreement is obtained between the measured results and those predicted by FEL simulations. Experiments have also been performed to study the expected variation in electron beam properties over a macropulse, which should be minimum for an oscillator FEL like the IR-FEL. This paper reports the results from the experiments for characterisation of the electron beam in the IR-FEL set-up and the results from FEL simulations, considering these measured electron beam parameters.
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Acknowledgements
The FEL development was done under a collaborative effort of different divisions of RRCAT in areas of RF and microwaves, vacuum, magnets, power supplies, alignment, workshops and controls. Their very valuable contribution is greatly acknowledged. Technical assistance of Mr Rajkumar Bhowate is also greatly acknowledged.
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Chandran, S., Biswas, B., Lal, S. et al. Commissioning and validation of the injector and electron beam transport systems for the IR-FEL at RRCAT. Pramana - J Phys 93, 85 (2019). https://doi.org/10.1007/s12043-019-1849-5
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DOI: https://doi.org/10.1007/s12043-019-1849-5