arXiv subjects

Steven P. Jamison

Publications and source records attributed to Steven P. Jamison.

7 recordsLinked to original sources

arXiv2026

Controlling external injection in laser-plasma accelerators with terahertz frequency bunch manipulation

Laser-plasma wakefield acceleration (LWFA) offers ultrahigh accelerating gradients in compact setups, but the complex non-linear nature of the process makes it challenging to generate high-quality beams. Injection of electron bunches from an external source into a plasma accelerator provides a promising route to improved performance; however, electron bunches from conventional radio-frequency (RF)-based injectors suffer from non-linear compression and laser-beam asynchrony, leading to energy jitter and emittance growth. We present a fundamental concept of terahertz-controlled electron bunches for external injection into LWFA. This terahertz-frequency approach provides temporal locking between the electron beam and the drive laser, and enables the compression of high-quality beams to sub-10-fs durations before injection into the LWFA. Numerical simulations demonstrate that GeV-scale acceleration with excellent beam quality and stability -- energy jitter and energy spread around 0.2% -- can be achieved using this method. This concept opens new opportunities for stable, multi-stage laser-driven accelerators and supports the development of next-generation applications such as free-electron lasers (FELs).

physics.acc-ph↗

arXiv2025

Average-power scalability of multi-cycle terahertz sources based on periodically poled lithium niobate stacks

We demonstrate that narrowband multi-cycle terahertz (MC-THz) sources based on periodically-poled lithium niobate (PPLN) wafer stacks can be driven by high repetition-rate, high energy femtosecond ytterbium-doped lasers. Operating at 10-kHz repetition rate with up to 104 W of pump power on a 10-wafer stack, we measure 26.4 mW of THz average power for a narrowband multi-cycle source. We identify and quantify strong lensing effects causing dramatic beam focusing in 47 wafer stacks which act as a primary limitation in the current configuration, and present mitigation strategies for future scaling. This first study of high average power narrowband multi-cycle THz sources offers a path forward to Watt-level high repetition rate sources using thin lithium niobate plates.

physics.optics↗

arXiv2025

Terahertz control of relativistic electron beams for femtosecond bunching and laser-synchronized temporal locking

Femtosecond relativistic electron bunches and micro-bunch trains synchronised with femtosecond precision to external laser sources are widely sought for next-generation accelerator and photonic technologies, from extreme UV and X-ray light sources for materials science, to ultrafast electron diffraction and future high-energy physics colliders. While few-femtosecond bunches have been demonstrated, achieving the control, stability and femtosecond-level laser synchronisation remains critically out of reach. Here we demonstrate a concept for laser-driven compression of high-energy (35.5 MeV) electron bunches with temporal synchronisation to a high-power (few-TW) laser system. Laser-generated multi-cycle terahertz (THz) pulses drive periodic electron energy modulation, enabling subsequent magnetic compression capable of generating tuneable picosecond-spaced bunch trains with 30 pC total charge and 50 A peak currents, or to compress a single bunch by a factor of 27 down to 15 fs duration. The THz-driven compression simultaneously drives temporal-locking of the bunch to the THz drive laser, providing a route to femtosecond-level synchronisation, overcoming the timing jitter inherent to radio-frequency accelerators and high-power laser systems. This THz technique offers compact and flexible bunch control with unprecedented temporal synchronisation, opening a pathway to unlock new capabilities for free electron lasers, ultrafast electron diffraction and novel plasma accelerators.

physics.acc-ph↗

arXiv2023

Broadband Terahertz Generation in a Corrugated Waveguide with matched Phase and Group Velocities

\begin{abstract} We show that it is possible to design corrugated waveguides where phase and group velocities coincide at an inflection point of the dispersion relation, allowing an extended regime of interaction with a charge particle beam. This provides a basis for designing travelling slow-wave structures with a broadband interaction between relativistic charged particle beams and propagating terahertz waves allowing an energy exchange between beam and wave, amplifying terahertz radiation. We employ Fourier-Mathieu expansion, which gives approximate analytic solutions to Maxwell equations in a corrugated waveguide with periodically undulating cross-section. Being analytic, this enables quick design of corrugated waveguides, determined from desirable dispersion relations. We design a three dimensional waveguide with the desired dispersion and confirm the analytical predictions of the wave profile, using numerical simulations. Madey's theorem is used to analyse the strength of the wave-beam interaction, showing that there is a broad frequency interaction region.

physics.app-ph↗

arXiv2019

Acceleration of relativistic beams using laser-generated terahertz pulses

Dielectric structures driven by laser-generated terahertz (THz) pulses may hold the key to overcoming the technological limitations of conventional particle accelerators and with recent experimental demonstrations of acceleration, compression and streaking of low-energy (sub-100 keV) electron beams, operation at relativistic beam energies is now essential to realize the full potential of THz-driven structures. We present the first THz-driven linear acceleration of relativistic 35 MeV electron bunches, exploiting the collinear excitation of a dielectric-lined waveguide driven by the longitudinal electric field component of polarization-tailored, narrowband THz pulses. Our results pave the way to unprecedented control over relativistic electron beams, providing bunch compression for ultrafast electron diffraction, energy manipulation for bunch diagnostics, and ultimately delivering high-field gradients for compact THz-driven particle acceleration.

physics.acc-ph↗

arXiv2015

The time resolved measurement of ultrashort THz-band electric fields without an ultrashort probe

The time-resolved detection of ultrashort pulsed THz-band electric field temporal profiles without an ultrashort laser probe is demonstrated. A non-linear interaction between a narrow-bandwidth optical probe and the THz pulse transposes the THz spectral intensity and phase information to the optical region, thereby generating an optical pulse whose temporal electric field envelope replicates the temporal profile of the real THz electric field. This optical envelope is characterised via an autocorrelation based FROG measurement, hence revealing the THz temporal profile. The combination of a narrow-bandwidth, long duration, optical probe and self-referenced FROG makes the technique inherently immune to timing jitter between the optical probe and THz pulse, and may find particular application where the THz field is not initially generated via ultrashort laser methods, such as the measurement of longitudinal electron bunch profiles in particle accelerators.

physics.optics↗

arXiv2015

Revealing Carrier-Envelope Phase through Frequency Mixing and Interference in Frequency Resolved Optical Gating

We demonstrate that full temporal characterisation of few-cycle electromagnetic pulses, including retrieval of the carrier envelope phase (CEP), can be directly obtained from Frequency Resolved Optical Gating (FROG) techniques in which the interference between non-linear frequency mixing processes is resolved. We derive a framework for this scheme, defined Real Domain-FROG (ReD-FROG), as applied to the cases of interference between sum and difference frequency components and between fundamental and sum/difference frequency components. A successful numerical demonstration of ReD-FROG as applied to the case of a self-referenced measurement is provided. A proof-of-principle experiment is performed in which the CEP of a single-cycle THz pulse is accurately obtained and demonstrates the possibility for THz detection beyond the bandwidth limitations of electro-optic sampling.

physics.optics↗