A pulsed-power electron accelerator using laser-driven photoconductive switches

This dissertation documents the experimental investigation of a novel electron accelerator. The characteristics of this device have been studied electrically and its performance has been assessed by measuring the properties of the electron beam produced by it. An understanding of the operation of this device has been aided by extensive modelling of the propagation of the electrical waveform through the structure as well as the response of the electron bunch to this pulse.; The reason for exploring new schemes for accelerating particles is to learn how to produce beams that have higher energy or can be focussed down to a smaller area. Our interest was to determine what maximum accelerating gradient could be achieved in a region where a bunch of electrons would be accelerated from rest. The device that was studied was a pulsed power radial transmission line accelerator. It has been predicted that one should be able to attain extremely high accelerating gradients in such structures. One feature of this device that has been predicted is that there should be an increase in the amplitude of the voltage pulse as it propagates into the center of the structure. In the laboratory we sampled the waveform electro-optically and observed a voltage gain by a factor of 4. This effect was modelled using two independent computer simulations. The electrical pulse was injected into the structure using photoconductive switches. Studies of the production of photoelectrons were carried out in anticipation of generating a beam of electrons from our device.; A series of experiments were carried out where the characteristics of the beam emitted from this accelerating structure were measured. The electron energy and amount of charge per bunch were measured as a function of the accelerating gap. The electron energy as a function of time relative to the accelerating pulse was modelled and the results indicate that the electrical pulse peaks for about 30 ps. The charge per bunch was typically 100 fC. The voltage was increased until the device failed. Failure occurred at a final electron energy of 11 keV after traversing a gap of 0.25 mm. This represents an average accelerating gradient of 44 MV/m.