A5030206583- Particle Accelerators and Free-Electron Lasers
- Terahertz technology and applications
- Gyrotron and Vacuum Electronics Research
- Particle accelerators and beam dynamics
- Laser-Plasma Interactions and Diagnostics
- Laser-Matter Interactions and Applications
- Advanced X-ray Imaging Techniques
- Photonic and Optical Devices
- Superconducting and THz Device Technology
- Particle Detector Development and Performance
- Superconducting Materials and Applications
- Laser Design and Applications
- Semiconductor Quantum Structures and Devices
- Spectroscopy and Laser Applications
- Laser-induced spectroscopy and plasma
- Advanced Surface Polishing Techniques
- Photonic Crystals and Applications
- Luminescence Properties of Advanced Materials
- Pulsed Power Technology Applications
- Laser Material Processing Techniques
- Advanced Fiber Laser Technologies
- Advanced Data Storage Technologies
- Advanced X-ray and CT Imaging
- Magnetic confinement fusion research
- Inorganic Fluorides and Related Compounds
Cockcroft Institute
2015-2024
Sci-Tech Daresbury
2013-2024
Lancaster University
2018-2024
University of Manchester
2015-2021
Science and Technology Facilities Council
2009-2019
Daresbury Laboratory
2007-2017
European Organization for Nuclear Research
2014
Technology Centre Prague
2007
Rutherford Appleton Laboratory
2007
University of Strathclyde
2000-2006
Quasi-optical techniques are used to efficiently couple freely propagating pulses of terahertz (THz) electromagnetic radiation into circular and rectangular metal waveguides. We have observed very dispersive, low-loss propagation over the frequency band from 0.65 3.5 THz with typical waveguide cross-section dimensions on order 300 µm lengths 25 mm. Classical theory is utilized calculate coupling coefficients modes for incoming focused beam. It shown that linearly polarized significantly only...
Waveguide propagation of sub-ps terahertz pulses in single-crystal sapphire fibers is reported. An incident THz pulse approximately 0.6 ps duration undergoes considerable reshaping due to the absorptive and dispersive waveguide propagation, resulting transmitted chirped durations 10–30 ps. Good agreement between theory experiment obtained by analyzing terms single HE11 mode. The dominance mode, despite fiber dimensions allowing for multimode attributed free-space coupling.
Electro-optic detection of the Coulomb field a relativistic electron bunch combined with single-shot cross correlation optical pulses is used to enable measurements shape and length femtosecond bunches. This method overcomes fundamental time-resolution limit previous electro-optic measurements, which arises from inseparability time frequency properties probing pulse. Using this new technique we have made real-time 50 MeV bunch, observing profile 650 fs FWHM ( approximately 275 rms) long
Highly collimated, quasimonoenergetic multi-MeV electron bunches were generated by the interaction of tightly focused, 80-fs laser pulses in a high-pressure gas jet. These monoenergetic are characteristic wakefield acceleration highly nonlinear wave breaking regime, which was previously thought to be accessible only much shorter thinner plasmas. In our experiment, initially long pulse modified underdense plasma match necessary conditions. This picture is confirmed semianalytical scaling laws...
Plasma waves excited by intense laser beams can be harnessed to produce femtosecond duration bunches of electrons with relativistic energies. The very large electrostatic forces plasma density wakes trailing behind an pulse provide field potentials capable accelerating charged particles high energies over short distances, as 1GeV in a few millimetres. length scale provides means developing compact high-energy accelerators, which could form the basis next-generation light sources unique...
We demonstrate a method to create arbitrary terahertz (THz) polarization profiles by exploiting the magnetic field-dependent emission process of spintronic source. As proof-of-concept, we show that applying specific field pattern source, it is possible generate quadrupole-like THz profile. Experimental measurements electric at focus beam revealed polarity flip in transverse profile mode with resulting strong, on-axis longitudinal component 17.7 kV cm−1. This represents an order magnitude...
Terahertz time–domain spectral techniques are applied to the characterization of a He discharge plasma. Electro-optically sampling electric field quasi-unipolar terahertz pulse transmitted through plasma has allowed both real and imaginary parts permittivity be simultaneously measured over large range. The density collisional frequency determined within 30 ps duration measurement window. An anomalously high been measured.
The longitudinal profiles of ultrashort relativistic electron bunches at the soft x-ray free-electron laser FLASH have been investigated using two single-shot detection schemes: an electro-optic (EO) detector measuring Coulomb field bunch and a radio-frequency structure transforming charge distribution into transverse streak. A comparison permits absolute calibration EO technique. signals as short 60 fs (rms) observed, which is new record in single close to limit given by material properties.
Precise measurements of the temporal profile ultrashort electron bunches are high interest for optimization and operation ultraviolet x-ray free-electron lasers. The electro-optic (EO) technique has been applied a single-shot direct visualization time individual at FLASH. This paper presents thorough description experimental setup results. An absolute calibration EO performed utilizing simultaneous with transverse-deflecting radio-frequency structure that transforms longitudinal bunch charge...
Laser-plasma wakefield-based electron accelerators are expected to deliver ultrashort bunches with unprecedented peak currents. However, their actual pulse duration has never been directly measured in a single-shot experiment. We present measurements of the such by means THz time-domain interferometry. With data obtained using 0.5 J, 45 fs, 800 nm laser and ZnTe-based electro-optical setup, we demonstrate laser-accelerated, quasimonoenergetic [best fit 32 fs (FWHM) 90% upper confidence level...
A technique for noncollinear cross correlation of electro-optic modulated optical pulses is presented the single-shot characterization terahertz waveforms and compared to established methods. This free from limitations on time resolution faithful reproduction previously demonstrated amplitude modulation spectral encoding.
The machine described in this document is an advanced Source of up to 20 MeV Gamma Rays based on Compton back-scattering, i.e. collision intense high power laser beam and a brightness electron with maximum kinetic energy about 720 MeV. Fully equipped collimation characterization systems, order generate, form fully measure the physical characteristics produced Ray beam. quality, phase space density, two colliding beams will be such that emitted ray characterized by tunability, spectral...
We investigate the use of tapered rectangular dielectric-lined waveguides (DLWs) for acceleration low-energy, subrelativistic, electron bunches by interaction with multicycle narrowband terahertz (THz) pulses. A key challenge exists in this subrelativistic regime; velocity changes significantly as energy is gained. To keep electrons accelerating phase, phase must also be increased to match. present simulations which demonstrate that dielectric thickness can kept constant and width lining...
This report describes the conceptual design of a proposed free electron laser test facility called CLARA that will be major upgrade to existing VELA accelerator at Daresbury Laboratory in UK. able number new schemes have been but require proof principle experiment confirm they perform as predicted. The primary focus on ultra short photon pulse generation which take lasers into whole regime, enabling area science emerge.
Periodically-poled lithium niobate (PPLN) sources consisting of custom-built stacks large-area wafers provide a unique opportunity to systematically study the multi-cycle terahertz (THz) generation mechanism as they are assembled layer-by-layer. Here we investigate and optimize THz emission from PPLN wafer function number, pump fluence, pulse duration chirp, separation, focusing. Using 135 µm-thick, 2"-diameter generate high-energy, narrowband pulses with central frequencies up 0.39 THz,...
Abstract Inverse Compton scattering is a promising method to implement high brightness, ultra-short, energy tunable X-ray source at accelerator facilities. We have developed an inverse backscattering driven by the multi-10 TW laser installed Daresbury. Hard X-rays, with spectral peaks ranging from 15 30 keV, depending on geometry, will be generated through interaction of pulses electron bunches delivered recovery linac machine, initially known as prototype and subsequently renamed...
The interaction of ultrashort laser pulses with krypton clusters at intensity up to 1.3×1018 Wcm−2 has been investigated. Intense Kα and Kβ emission from 12.66 14.1 keV, respectively, observed using conventional solid state x-ray detectors. measured spectra have broad bremsstrahlung continuum reaching photon energies 45 evidence that approximately 10% electrons are heated very high electron temperatures, which is consistent a two-temperature distribution. This ascribed the presence hot...
The sub-luminal phase velocity of electromagnetic waves in free space is generally unobtainable, being closely linked to forbidden faster than light group velocities. requirement effective phase-velocity laser-driven particle acceleration schemes imposes a fundamental limit on the total achievable free-space, and necessitates use dielectric structures waveguides for extending field-particle interaction. Here we demonstrate new travelling-source propagation approach overcoming limits....
The electro-optic effect between an ultrafast optical probe pulse and ultrashort terahertz is shown to depend on the time derivatives of product electric fields. Application this theory temporally resolved single-shot detection techniques, where localized within pulse, shows that description presented here differs fundamentally verifiably from commonly used in literature.
We demonstrate the generation of near-single cycle longitudinally polarized terahertz radiation using a large-area radially biased photoconductive antenna with longitudinal field amplitude in excess 2 kV/cm. The 76 mm diameter was photo-excited by 0.5 mJ amplified near-infrared femtosecond laser system and voltage up to 100 kV applied over concentric electrodes. Amplitudes for both transverse components source were measured calibrated electro-optic detection scheme. By tightly focusing...
We demonstrate the generation of single-cycle longitudinally polarized terahertz pulses with field amplitudes in excess 11 kV/cm using interferometric recombination two linearly beams. High strength transversely were generated by optical rectification a matched pair magnesium-oxide doped stoichiometric lithium niobate (MgO:SLN) crystals reversal χ333(2) orientation. The discontinuity produces polarity flip transverse field; longitudinal produced as consequence was measured far-field. Both...