A5032981945- Laser-Plasma Interactions and Diagnostics
- Laser-Matter Interactions and Applications
- Laser-induced spectroscopy and plasma
- Laser Design and Applications
- Advanced X-ray Imaging Techniques
- Particle Accelerators and Free-Electron Lasers
- Radiation Therapy and Dosimetry
- Terahertz technology and applications
- High-pressure geophysics and materials
- Nuclear Physics and Applications
- Advanced Radiotherapy Techniques
- Photonic and Optical Devices
- Gyrotron and Vacuum Electronics Research
- Laser Material Processing Techniques
- Plasmonic and Surface Plasmon Research
- Semiconductor Quantum Structures and Devices
- Pulsed Power Technology Applications
- Spectroscopy and Laser Applications
- Spectroscopy and Quantum Chemical Studies
- Advanced Surface Polishing Techniques
- Advanced X-ray and CT Imaging
- Particle accelerators and beam dynamics
- Advanced Optical Sensing Technologies
- Radiation Effects and Dosimetry
- Superconducting and THz Device Technology
University of Strathclyde
2011-2023
Scottish Universities Physics Alliance
2011-2023
Public Citizen
2021
Cockcroft Institute
2019
MGS Research (United States)
2012
Indiana University Health
2012
Indiana University – Purdue University Indianapolis
2012
Progress in laser wakefield accelerators indicates their suitability as a driver of compact free-electron lasers (FELs). High brightness is defined by the normalized transverse emittance, which should be less than 1π mm mrad for an x-ray FEL. We report high-resolution measurements emittance 125 MeV, monoenergetic beams from accelerator. An low 1.1±0.1π measured using pepper-pot mask. This sets upper limit on comparable with conventional linear accelerators. A peak 5×10¹⁵ m⁻¹ rad⁻¹ makes it...
The second-order processes of optical-rectification and photoconduction are well known widely used to produce ultrafast electromagnetic pulses in the terahertz frequency domain. We present a new form rectification that relies on excitation surface plasmons metal films deposited shallow grating. Multiphoton ionization ponderomotive acceleration electrons enhanced evanescent field results femtosecond current surge emission radiation. Using gold, this process is third or higher-order incident field.
The increased inertia of very high-energy electrons (VHEEs) due to relativistic effects reduces scattering and enables irradiation deep-seated tumours. However, entrance exit doses are high for collimated or diverging beams. Here, we perform a study based on Monte Carlo simulations focused VHEE beams in water phantom, showing that dose can be concentrated into small, well-defined volumetric element, which shaped scanned treat surrounding tissue is distributed over larger volume, peak surface...
A resonant "incoherent" rectification process is presented relying on the excitation of surface plasmons a nanostructured metal surface. Excitation gold and silver films with 800-nm femtosecond laser pulses results in emission terahertz radiation an angle-dependent efficiency approximately third-order power dependence. It shown that source this pulse generation surface-plasmon-assisted multiphoton ionization ponderomotive acceleration evanescent field plasmon. Simple models are used to...
High quality electron beams have been produced in a laser-plasma accelerator driven by femtosecond laser pulses with peak power of 26 TW. Electrons are an energy up to 150 MeV from the 2 mm gas jet and measured rms relative spread is less than 1%. Shot-to-shot stability central 3%. Pepper-pot measurements shown that normalized transverse emittance ∼1π mrad while beam charge range 2–10 pC. The generation high understood simulations accounting for loading wakefield accelerating structure....
Raman amplification in plasma has been proposed to be a promising method of amplifying short radiation pulses. Here, we investigate chirped pulse (CPRA) where the pump is and leads spatiotemporal distributed gain, which exhibits superradiant scaling linear regime, usually associated with nonlinear depletion Compton regimes. CPRA potential serve as high-efficiency high-fidelity amplifier/compressor stage.
Very high energy electrons (VHEE) in the range from 100 to 250 MeV have potential of becoming an alternative modality radiotherapy because their improved dosimetry properties compared with MV photons contemporary medical linear accelerators.Due need for accurate small field size VHEE beams we performed dose measurements using EBT2 Gafchromic® film.Calibration film has been carried out two different ranges: 20 and 165 conventional radio frequency accelerators.In addition, used 135 electron...
The laser driven plasma wakefield accelerator is a very compact source of high energy electrons. When the quasi-monoenergetic beam from these accelerators passes through dense material, bremsstrahlung photons are emitted in collimated with flux. We show how based on this emission process can produce more than 109 per pulse mean 10 MeV. present experimental results that feasibility method producing and compare GEANT4 Montecarlo simulations, which also give scaling required to evaluate its...
Abstract Space radiation is a great danger to electronics and astronauts onboard space vessels. The spectral flux of electrons, protons ions for example in the belts inherently broadband, but this feature hard mimic with conventional sources. Using laser-plasma-accelerators, we reproduced relativistic, broadband belt laboratory, used man-made test hardness electronics. Such close mimicking lab builds on inherent ability laser-plasma-accelerators directly produce Maxwellian-type particle...
Abstract Raman amplification arising from the excitation of a density echelon in plasma could lead to amplifiers that significantly exceed current power limits conventional laser media. Here we show 1–100 J pump pulses can amplify picojoule seed nearly joule level. The extremely high gain also leads significant backscattered radiation “noise”, stochastic fluctuations competes with externally injected pulses, which are amplified similar levels at highest energies. energy is scattered into an...
The laser–plasma wakefield accelerator is a compact source of high brightness, ultra-short duration electron bunches. Self-injection occurs when electrons from the background plasma gain sufficient momentum at back bubble-shaped accelerating structure to experience sustained acceleration. shortest and highest brightness bunches result self-injection close threshold for injection. Here we show that in this case injection due localized charge density build-up sheath crossing region rear...
Narrow band undulator radiation tuneable over the wavelength range of 150–260 nm has been produced by short electron bunches from a 2 mm long laser plasma wakefield accelerator based on 20 TW femtosecond system. The number photons measured is up to 9 × 106 per shot for 100 period undulator, with mean peak brilliance 1 1018 photons/s/mrad2/mm2/0.1% bandwidth. Simulations estimate that driving bunch r.m.s. duration as 3 fs when beam energy 120–130 MeV pulse in 50–100 fs.
Very high energy electrons (VHEE) in the range from 100 to 250MeV have potential of becoming an alternative modality radiotherapy because their improved dosimetric properties compared with 6-20MV photons generated by clinical linear accelerators (LINACs). VHEE beams characteristics unlike any other currently used for radiotherapy: femtosecond picosecond duration electron bunches, which leads very dose per pulse, and energies that exceed applications. Dosimetry conventional online detectors,...
Abstract Stimulated Raman backscattering in plasma is potentially an efficient method of amplifying laser pulses to reach exawatt powers because fully broken down and withstands extremely high electric fields. Plasma also has unique nonlinear optical properties that allow simultaneous compression ultra-short durations. However, current measured efficiencies are limited several percent. Here we investigate amplification short duration seed with different chirp rates using a chirped pump pulse...
Abstract Laser-wakefield accelerators are compact devices capable of delivering ultra-short electron bunches with pC-level charge and MeV-GeV energy by exploiting the ultra-high electric fields arising from interaction intense laser pulses plasma. We show experimentally through numerical simulations that a high-energy beam is produced simultaneously two stable lower-energy beams ejected in oblique counter-propagating directions, typically carrying off 5–10% initial energy. A MeV, 10s nC...
Gas-filled capillary discharge waveguides are commonly used as media for plasma wakefield accelerators. We show that effective can be manufactured using a femtosecond laser micromachining technique to produce linearly tapered density, which enables the energy of accelerator enhanced significantly. A guiding efficiency in excess 82% at sub-relativistic intensities has been demonstrated 40 mm long with diameter tapering from 320 μm 270 μm, gives rise an on-axis, time-averaged density varies...
Electron beams from laser-plasma wakefield accelerators have low transverse emittance, comparable to those conventional radio frequency accelerators, which highlights their potential for applications, many of will require the use quadrupole magnets optimal electron beam transport.We report on characterizing bunches where double are observed under certain conditions.In particular, we present pepper-pot measurements emittance 120-200 MeV laser after propagation through a triplet permanent...
Abstract High power lasers have become useful scientific tools, but their large size is determined by low damage-threshold optical media. A more robust and compact medium for amplifying manipulating intense laser pulses plasma. Here we demonstrate, experimentally through simulations, that few-millijoule, ultra-short seed interacting with 3.5-J counter-propagating pump in plasma, stimulate back-scattering of nearly 100 mJ energy high intrinsic efficiency, when detuned from Raman resonance....
Citizen social science has been developing in meaning and prevalence over the past few years, building on experiences with both citizen (natural) established methods such as participatory action research. However, most of debate is still at conceptual level, strong calls for more empirical insight. Here, we critically examine promises challenges science, based two small-scale, co-created locally embedded projects people’s relationships urban greenspaces community food growing, conducted a...
Focussing ultra-short electron bunches from a laser-plasma wakefield accelerator into an undulator requires particular attention to be paid the emittance, bunch duration and energy spread. Here we present design implementation of focussing system for ALPHA-X beam transport line, which consists triplet permanent magnet quadrupoles electromagnetic quadrupoles.
We present an all solid-state, high voltage pulsed power supply for inducing stable plasma formation (density ∼10(18) cm(-3)) in gas-filled capillary discharge waveguides. The pulser (pulse duration of 1 μs) is based on transistor switching and wound transmission line transformer technology. For a length 40 mm diameter 265 μm gas backing pressure 100 mbar, fast pulse risetime 95 ns initiates breakdown at 13 kV along the capillary. A peak current ∼280 indicates near complete ionization,...
Gas-filled capillary discharge waveguides are important structures in laser-plasma interaction applications, such as the laser wakefield accelerator. We present methodology for applying femtosecond micromachining production of channels (typically 200-300 μm diameter and 30-40 mm length), including formalism capillaries with a linearly tapered diameter. The latter is demonstrated to possess smooth variation along length (tunable trajectories). This would lead longitudinal plasma density...
Compton side-scattering has been used to simultaneously downshift the energy of keV MeV range photons while attenuating their flux enable single-shot, spectrally resolved, measurements high X-ray sources be undertaken. To demonstrate technique a 1 mm thick pixelated cadmium telluride detector measure spectra side-scattered radiation from Cobalt-60 laboratory source and flux, peak brilliance betatron laser-plasma wakefield accelerator.
As an alternative modality to conventional radiotherapy, electrons with energies above 50 MeV penetrate deeply into tissue, where the dose can be absorbed within a tumour volume relatively small penumbra. We investigate physical properties of VHEEs and review state-of-the-art in treatment planning dosimetry. discuss advantages using laser wakefield accelerator (LWFA) present characteristic features electron bunch produced by LWFA compare them that from linear accelerator.