Plasma accelerator-based ultrabright x-ray beams from ultrabright electron beams

We provide a pathway to compact ultrabright light sources, based on ultrabright, high energy electron beams emerging from a combination of plasma Wakefield acceleration and plasma photocathodes. While plasma acceleration is known to produce accelerating fields three or four orders of magnitude larger than conventional accelerators, the plasma photocathode allows production of electron beams three or four orders of magnitude brighter than conventional, and thus is suitable to unleash the full potential of plasma accelerators. In particular, this is the case for various types of light sources, which profit enormously from an increased electron beam brightness. Building on the recent first experimental demonstration of the plasma photocathode, in this work we discuss the prospects of plasma photocathodes for key photon source approaches such as x-ray free-electron lasers, betatron radiation, ion-channel lasers and inverse Compton scattering

Angled laser triggered electron injection in the electron driven plasma wakefield acceleration scheme : a case study in a pursuit to increase tolerance levels, based on FACET II driver parameters.

Co-axial laser triggered injection of electrons in PWFA can produce high quality witness bunches. In this study, angled injection was examined in a pursuit to increase the tolerance levels of synchronization and experimental misalignments while maintaining the high quality of the witness bunches

Plasma-photonic spatiotemporal synchronization of relativistic electron and laser beams

Modern particle accelerators and their applications increasingly rely on precisely coordinated interactions of intense charged particle and laser beams. Femtosecond-scale synchronization alongside micrometre-scale spatial precision are essential e.g. for pump-probe experiments, seeding and diagnostics of advanced light sources and for plasma-based accelerators. State-of-the-art temporal or spatial diagnostics typically operate with low-intensity beams to avoid material damage at high intensity. As such, we present a plasma-based approach, which allows measurement of both temporal and spatial overlap of high-intensity beams directly at their interaction point. It exploits amplification of plasma afterglow arising from the passage of an electron beam through a laser-generated plasma filament. The corresponding photon yield carries the spatiotemporal signature of the femtosecond-scale dynamics, yet can be observed as a visible light signal on microsecond-millimetre scales

Electron bunch generation from a plasma photocathode

Plasma waves generated in the wake of intense, relativistic laser or particle beams can accelerate electron bunches to giga-electronvolt (GeV) energies in centimetre-scale distances. This allows the realization of compact accelerators having emerging applications, ranging from modern light sources such as the free-electron laser (FEL) to energy frontier lepton colliders. In a plasma wakefield accelerator, such multi-gigavolt-per-metre (GV m$^{-1}$) wakefields can accelerate witness electron bunches that are either externally injected or captured from the background plasma. Here we demonstrate optically triggered injection and acceleration of electron bunches, generated in a multi-component hydrogen and helium plasma employing a spatially aligned and synchronized laser pulse. This ''plasma photocathode'' decouples injection from wake excitation by liberating tunnel-ionized helium electrons directly inside the plasma cavity, where these cold electrons are then rapidly boosted to relativistic velocities. The injection regime can be accessed via optical density down-ramp injection, is highly tunable and paves the way to generation of electron beams with unprecedented low transverse emittance, high current and 6D-brightness. This experimental path opens numerous prospects for transformative plasma wakefield accelerator applications based on ultra-high brightness beams

High-brightness plasma-based Compton backscattering source for high energy physics

Incorrct date on title page (2019). Date of award was 2020.Exciting, probing and manipulating the quantum states of nuclei is crucial to many scientific, industrial, medical and defence applications of high energy physics. Inverse Compton scattering (ICS) offers the necessary MeV-level photon energies along with highly directed and collimated pulse profiles. However, respective facilities are scarce as the large underlying particle accelerators cause high costs. Plasma accelerators, in contrast, offer orders of magnitude higher accelerating fields and can operate sensibly priced in considerably smaller laboratories. State-of-the-art experiments have routinely shown generation of dense electron beams suitable for MeV-photon pulses with extremely high peak brilliance. Yet, plasma accelerators suffer from large energy spread and emittance that cause spectral broadening impractical for many nuclear applications.This work investigates the prospects of plasma photocathode wakefield accelerators generating low-emittance, high-quality electron beams for ICS. An important component is the experimental demonstration of a novel, plasma-based diagnostic for spatiotemporal synchronisation and alignment of electron and laser beams.This multi-shot method yields absolute time-of-arrival accuracy of ~16 fs and alignment accuracy of 4 μm. It has facilitated the word's first experimental realisation of a plasma photocathode and the plasma torch injection method. These experiments represent milestones towards highest-quality electron beam production, and are fundamental to plasma-based generation of brilliant, narrow-bandwidth and MeV-level-ray sources. Extensive simulations investigate their production and reveal unprecedented single-shot peak brilliance of ~1 1025 photons s-1 mm-2 mrad-2 0.1%BWat 0.4MeV to 9MeV.This work further outlines the generation of inherently synchronised and brilliant-ray pairs, which constitute temporally and spectrally fully separable multi-colour radiation. The underlying effect can further minimise electron beam energy spread.This is shown to shrink the relative -ray bandwidth to 2.3% at 2.4MeV, and overcomes one of the major problems in plasma accelerators and ICS sources. Each part of this work advances its respective research area, yet combined they promise the highest-quality photon sources for nuclear physics applications.Exciting, probing and manipulating the quantum states of nuclei is crucial to many scientific, industrial, medical and defence applications of high energy physics. Inverse Compton scattering (ICS) offers the necessary MeV-level photon energies along with highly directed and collimated pulse profiles. However, respective facilities are scarce as the large underlying particle accelerators cause high costs. Plasma accelerators, in contrast, offer orders of magnitude higher accelerating fields and can operate sensibly priced in considerably smaller laboratories. State-of-the-art experiments have routinely shown generation of dense electron beams suitable for MeV-photon pulses with extremely high peak brilliance. Yet, plasma accelerators suffer from large energy spread and emittance that cause spectral broadening impractical for many nuclear applications.This work investigates the prospects of plasma photocathode wakefield accelerators generating low-emittance, high-quality electron beams for ICS. An important component is the experimental demonstration of a novel, plasma-based diagnostic for spatiotemporal synchronisation and alignment of electron and laser beams.This multi-shot method yields absolute time-of-arrival accuracy of ~16 fs and alignment accuracy of 4 μm. It has facilitated the word's first experimental realisation of a plasma photocathode and the plasma torch injection method. These experiments represent milestones towards highest-quality electron beam production, and are fundamental to plasma-based generation of brilliant, narrow-bandwidth and MeV-level-ray sources. Extensive simulations investigate their production and reveal unprecedented single-shot peak brilliance of ~1 1025 photons s-1 mm-2 mrad-2 0.1%BWat 0.4MeV to 9MeV.This work further outlines the generation of inherently synchronised and brilliant-ray pairs, which constitute temporally and spectrally fully separable multi-colour radiation. The underlying effect can further minimise electron beam energy spread.This is shown to shrink the relative -ray bandwidth to 2.3% at 2.4MeV, and overcomes one of the major problems in plasma accelerators and ICS sources. Each part of this work advances its respective research area, yet combined they promise the highest-quality photon sources for nuclear physics applications

Fundamentals and Applications of Hybrid LWFA-PWFA

International audienceFundamental similarities and differences between laser-driven plasma wakefield acceleration (LWFA) Plasma Wakefield Acceleration (PWFA)  and particle-driven plasma wakefield acceleration (PWFA) Plasma Wakefield Acceleration (PWFA)  are discussed. The complementary features enable the conception and development of novel hybrid plasma acceleratorsLaser-plasma accelerator, which allow previously not accessible compact solutions for high quality electron bunchElectron bunch generation and arising applications. Very high energy gains can be realized by electron beam drivers even in single stages because PWFA is practically dephasing-free and not diffraction-limited. These electron driver beams for PWFA in turn can be produced in compact LWFA stages. In various hybrid approaches, these PWFA systems can be spiked with ionizing laser pulses to realize tunable and high-quality electron sources via optical density downramp injectionDownramp injection (also known as plasma torch) Plasma torch  or plasma photocathodesPlasma photocathode (also known as Trojan Horse) and via wakefield-induced injection (also known as WII). These hybrids can act as beam energy, brightness and quality transformers, and partially have built-in stabilizing features. They thus offer compact pathways towards beams with unprecedented emittanceEmittance and brightness, which may have transformative impact for light sources and photon science applications. Furthermore, they allow the study of PWFA-specific challenges in compact setups in addition to large linac-based facilities, such as fundamental beam–plasma interaction physics, to develop novel diagnostics, and to develop contributions such as ultralow emittanceEmittance test beams or other building blocks and schemes which support futurePlasma-based collider plasma-based collider concepts