THz-frequency accelerating structures could provide the accelerating gradients needed for compact next generation particle accelerators. One of the most promising THz generation techniques for accelerator applications is optical rectification in lithium niobate using the tilted pulse front method. However, accelerator applications are limited by losses during transport and coupling of THz radiation to the acceleration structure. Applying the near-field of the lithium niobate source directly to the electron bunch removes losses due to transport and coupling, yielding a simplified and efficient system. Using electro-optic sampling we have reconstructed the full temporal 3D THz near-field close to the lithium niobate emission face and shown that it can be controlled by manipulating the generation setup. Analysis of the results of this measurement shows an estimated peak field strength of 86 MV/m. A future THz near-field electron streaking experiment is currently planned as a first test of manipulating an electron bunch with the THz near field. Analysis for this planned experiment has yielded an estimated THz near-field kick strength of 23 keV.

The favorable wavelength scaling of ponderomotive interactions indicates that long-wave infrared (LWIR) lasers are well suited for applications such as laser wakefield acceleration and high harmonic generation. CO2 amplifiers are the primary source of such wavelengths, able to generate TW peak powers with sub-ps pulse lengths. However, a limiting factor for these amplifiers is the necessity of using electrical discharges to pump the gain medium, reducing the maximum repetition rate and energy stability. This can be mitigated by instead optically pumping the CO2 at 4.5 μm. We demonstrate a proof of principle of the generation of this wavelength by utilizing stimulated Raman scattering, a process where photons inelastically scatter from a material. For this wavelength, we employ a novel class of material known as ionic liquids as the Raman medium. We demonstrate efficient conversion from a 532 nm frequency doubled Nd:YAG laser to 603 nm in the ionic liquid EMIM DCA, followed by performing difference frequency generation to produce the 4.5 μm pump.

An analytical form is derived using the Faddeeva function to represent terahertz-frequency pulses generated by optical rectification of ultrashort laser pulses. Spectra of these pulses can be described by a Gaussian fall-off at high frequencies and a power-law as DC is approached. A set of pulsed beams based on this form is also derived for the special case of propagation-invariant spatio-temporal coupling (iso-diffracting). Motion of charged particles in these pulsed beams is considered analytically and numerically and energy gain is computed and compared with ponderomotive force laws. Particle motion in more complex pulsed-beam fields is also considered.

THz-frequency accelerating structures could provide the accelerating gradients needed for compact next generation particle accelerators. One of the most promising THz generation techniques for accelerator applications is optical rectification in lithium niobate using the tilted pulse front method. However, accelerator applications are limited by losses during transport and coupling of THz radiation to the acceleration structure. Applying the near-field of the lithium niobate source directly to the electron bunch removes losses due to transport and coupling, yielding a simplified and efficient system. Using electro-optic sampling we have reconstructed the full temporal 3D THz near-field close to the lithium niobate emission face and shown that it can be controlled by manipulating the generation setup. Analysis of the results of this measurement shows an estimated peak field strength of 86 MV/m. A future THz near-field electron streaking experiment is currently planned as a first test of manipulating an electron bunch with the THz near field. Analysis for this planned experiment has yielded an estimated THz near-field kick strength of 23 keV.