UCLA

Conventional accelerators use RF fields on the order of 10-100~MV/m to accelerate particles, but the cavities which support these fields are large and expensive, as are the power sources. With the advent of dielectric materials that can withstand GV/m fields, higher gradient photonic structures that can be mass-produced using modern nanofabrication techniques have become of great interest. Due to the extremely small size of the accelerating channels, GV/m field intensities can be achieved using modest ($\mu$J to mJ) pulse energies from widely available compact laser sources. Not only do these dielectric laser accelerators (DLAs) promise to shrink accelerator dimensions, fabrication and operation costs by several orders of magnitude, they also enable the generation of electron bunches with sub-nm normalized emittances and attosecond characteristic time scales.

This is not without its problems; the small apertures which enable such fields are accompanied by low particle acceptance. In addition, to take full advantage of the high damage threshold of dielectric material we must operate with femtosecond scale laser pulses, which limits the interaction between laser and electron. By introducing a pulse front tilt laser, we can mitigate this, but phase matching the slower than light electrons to the laser drive eventually puts an end to enery gain, regardless.

In this thesis, we address these issues by applying progress in optical techniques that has made precision control of the phase profile in optical pulses common and available in scientific laboratories. We make use of a liquid crystal mask in the form of a spatial light modulator in order to programmably control our laser drive, and therefore electron beam, in concert with a pulse front tilted drive laser. The drive laser is designed with the use of a 4-d matrix calculation and measured with a cross-correlation interferometric diagnostic. We explore how use of programmable optical components could lead to higher quality beams in the present and future. In order to maximize our interaction lengths, we also design and implement a tunable structure of 5~millimeter length which allows for significant improvements in energy gain. The structures are characterized in air through the use of a diode laser optical diagnostic. Finally, electron beam based experiments take place at the Pegasus beamline at UCLA with initial energies from 6-8~MeV.

In the first chapter, we discuss the fields and forces within DLA structures, as well as the design for a tunable DLA structure and optical diagnostic. Next, we discuss the optical setup and programmable DLA manipulation. The last chapter can be considered in two parts. First, we discuss the beam dynamics challenges inherent to DLA as well as some possible accelerator designs. In the second part, we look at the experiments which serve as progress toward these eventual accelerator designs. The first experiment demonstrates the wide acceptance of DLA and laser manipulation possibilities. The second implements a tunable structure using commercial gratings, proving that the tunable structure design was feasible for custom structures. Finally, the last experiment combines tunable structure with a programmable laser phase and amplitude scheme, demonstrating a near 5 millimeter interaction in a DLA. Additionally, we demonstrate a record 0.5~MeV energy gain.