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abstract:
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This thesis presents the UCLA high gain free electron laser (FEL). FELs have long been proposed as sources of radiation in regimes diffuclt to obtain with conventional lasers. High average power, microwave, far-IR, UV and X-ray are regimes and charactericstics difficult for conventional lasers to achieve. Free Electron Lasers, in principle, do not suffer from the same limitations (atomic transitions, heat dissimpation, thermal lensing, etc.) as atomic and molecular lasers. However, oscillator FELs are still impeded by the need for suitable optics. A high gain FEL, on the other had, requires no oscillator, and can operate in regimes where high quality optics are unavailable. A high gain FEL which requires no input signal, and amplifies the spontaneous emission produced by its own beam is said to operating in the Self Amplified Spontaneous Emission (SASE) mode. A SASE FEL can operate at wavelenghts where no conventional coherent sources are available (i.e., x-rays).
High gain FEL experimental work has been very limited, with only a few experiments performed at "optical" wavelengths. No SASE FEL has been operated outside the microwave regime. This work describes an experiment designed to verify the models of high gain FELs, and operate an infrared SASE FEL.
High gain FEL theory is reviewed. An analysis of the PBPL FEL is made using analytic as well as numerical models. Experimental effects such as the limited accuracy of beam diagnostics are taken into account. It is show that there are great experimental problems to over come in attempting to determine the preformance and effective start-up level of the PBPL FEL. Some of these difficulties are expected to be shared by future high gain FELs.
The PBPL experiment is described with an exphasis on operational problems significant to the FEL. The accelerator, beamline components and diagnostics are described in detail along with design issues and performance parameters. The FEL undulator and optical diagnostics are also described and test data is given.
This thesis shows the complexities associated with a high gain FEL, and attempts to determine what can be learned from such an experiment.
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