A5074894870- Laser-Plasma Interactions and Diagnostics
- Particle Accelerators and Free-Electron Lasers
- Plasma Diagnostics and Applications
- Particle accelerators and beam dynamics
- Laser-induced spectroscopy and plasma
- Plasma Applications and Diagnostics
- Electrohydrodynamics and Fluid Dynamics
- Magnetic confinement fusion research
- Advanced X-ray Imaging Techniques
- Nuclear Physics and Applications
- Pulsed Power Technology Applications
- Laser Design and Applications
- Laser-Matter Interactions and Applications
- Plasma and Flow Control in Aerodynamics
- Ion-surface interactions and analysis
- Particle Detector Development and Performance
- Advanced Surface Polishing Techniques
- Mass Spectrometry Techniques and Applications
- Vacuum and Plasma Arcs
- Radiation Therapy and Dosimetry
- High-pressure geophysics and materials
- Atomic and Molecular Physics
- Digital Radiography and Breast Imaging
- Thin-Film Transistor Technologies
- Electrostatic Discharge in Electronics
Deutsches Elektronen-Synchrotron DESY
2013-2024
Universität Hamburg
2012-2022
University College London
2022
University of Strathclyde
2022
Cockcroft Institute
2022
Queen's University Belfast
2008-2020
Ruhr University Bochum
2007
Despite enormous potential for technological applications, fundamentals of stable non-equilibrium micro-plasmas at ambient pressure are still only partly understood. Micro-plasma jets one sub-group these plasma sources. For an understanding it is particularly important to analyse transport phenomena energy and particles within between the core effluent discharge. The complexity problem requires combination correlation various highly sophisticated diagnostics yielding different information...
Active plasma lensing is a compact technology for strong focusing of charged particle beams, which has gained considerable interest use in novel accelerator schemes. While providing $\mathrm{kT}/\mathrm{m}$ gradients, active lenses can have aberrations caused by radially nonuniform temperature profile, leading to degradation the beam quality. We present first direct measurement this aberration, consistent with theory, and show that it be fully suppressed changing from light gas species...
A tunable plasma-based energy dechirper has been developed at FLASHForward to remove the correlated spread of a 681 MeV electron bunch. Through interaction bunch with wakefields excited in plasma projected was reduced from FWHM 1.31% 0.33% without reducing stability incoming beam. The experimental results for variable density are good agreement analytic predictions and three-dimensional simulations. proof-of-principle dechirping strength 1.8 GeV/mm/m significantly exceeds those demonstrated...
Energy-efficient plasma-wakefield acceleration of particle bunches with low energy spread is a promising path to realizing compact free-electron lasers and colliders. High efficiency can be achieved simultaneously by strong beam loading plasma wakefields when accelerating carefully tailored current profiles [M. Tzoufras et al., Phys. Rev. Lett. 101, 145002 (2008)]. We experimentally demonstrate such optimal in nonlinear electron-driven accelerator. Bunches an initial 1 GeV were accelerated...
Abstract Micro plasmas operated at ambient pressure with dimensions of the confining geometry in order a few ten micrometers to millimeter are actually focus interest due broad regime applicability they offer and similarly range open physical questions. Here we present optical measurements within discharge core effluent region an especially developed micro jet. To get understanding complex system this it is important analyse transport phenomena energy particles both parts by various highly...
The production of plasmas in saline solution at low voltage (here 225 V) is investigated. It confirmed that this associated with vapour layer formation on the electrode surface. occur once has completely covered and reached a thickness approximately 0.3 mm. There are several aspects specific environment may influence breakdown characteristics layer. These include high electric fields, approaching 107 V m−1, layer, presence sodium chlorine surface generally different character each pulse....
Experimental and finite element modelling methods are used to study the formation of vapour layers in electrical discharges through saline solutions. The experiments utilize shadowgraphic photometric observe time dependence thin plasma around electrodes driven by moderate voltage (<500 V) pulses, applied an electrode immersed a conducting solution. Finite multiphysics software, coupling thermal effects, is employed model layer formation. All relevant properties incorporated into model, but...
We propose a new and simple strategy for controlled ionization-induced trapping of electrons in beam-driven plasma accelerator. The presented method directly exploits electric wakefields to ionize from dopant gas capture them into well-defined volume the accelerating focusing wake phase, leading high-quality witness bunches. This injection principle is explained by example three-dimensional particle-in-cell calculations using code OSIRIS. In these simulations high-current-density...
Abstract The free-electron laser in Hamburg, FLASH, is the first extreme ultra-violet and soft X-ray (FEL) user facility has been continuously upgraded since its start 2005. Further major works are currently underway within FLASH2020+ project that pioneeringly implements full repetition rate external seeding at a superconducting accelerator facility. With fully tunable undulators providing variable polarization FEL pulses, we expect FLASH to turn into ideal spectroscopy machine for ultrafast...
This document provides detailed information on the status of Advanced and Novel Accelerators techniques describes steps that need to be envisaged for their implementation in future accelerators, particular high energy physics applications. It complements overview prepared update European Strategy particle physics, a description field. The scientific priorities community are described each technique acceleration able achieve accelerating gradient GeV~range or above. ALEGRO working group...
The atmospheric pressure plasma jet (APPJ) is a homogeneous non-equilibrium discharge at ambient pressure. It operates with noble base gas and percentage-volume admixture of molecular gas. Applications the are mainly based on reactive species in effluent. effluent region operated helium an oxygen has been investigated. optical emission from atomic decreases distance but can still be observed several centimetres Ground state oxygen, measured using absolutely calibrated two-photon laser...
The FLASHForward experimental facility is a high-performance test-bed for precision plasma wakefield research, aiming to accelerate high-quality electron beams GeV-levels in few centimetres of ionized gas. created by ionizing gas cell either high-voltage discharge or high-intensity laser pulse. electrons be accelerated will injected internally from the background externally FLASH superconducting RF front end. In both cases, driven provided gun and linac modules operating with 10 Hz...
We present a detailed analysis of the features and capabilities Wakefield-Induced Ionization (WII) injection in blowout regime beam driven plasma accelerators. This mechanism exploits electric wakefields to ionize electrons from dopant gas trap them well-defined region accelerating focusing wake phase, leading formation high-quality witness-bunches [Martinez de la Ossa et al., Phys. Rev. Lett. 111, 245003 (2013)]. The electron-beam drivers must feature high-peak currents (Ib0≳8.5 kA)...
Precise characterization and tailoring of the spatial temporal evolution plasma density within sources is critical for realizing high-quality accelerated beams in wakefield accelerators. The simultaneous use two independent diagnostic techniques allowed temporally spatially resolved detection with unprecedented sensitivity enabled temperature at local thermodynamic equilibrium discharge capillaries. A common-path two-color laser interferometer obtaining average a $2\times 10^{15}$ cm$^{-2}$...
The complex dynamics of radio-frequency driven atmospheric pressure plasma jets is investigated using various optical diagnostic techniques and numerical simulations. Absolute number densities ground state atomic oxygen radicals in the effluent are measured by two-photon absorption laser induced fluorescence spectroscopy (TALIF). Spatial profiles compared with (vacuum) ultra-violet radiation from excited states molecular oxygen, respectively. excitation ionization core dominated electron...
Discharge capillary-based active plasma lenses are a promising new technology for strongly focusing charged particle beams, especially when combined with novel high gradient acceleration methods. Still, many questions remain concerning such lenses, including their transverse field uniformity, limitations due to wakefields and whether they can be in multi-lens lattices way cancel chromaticity. These will addressed lens experiment at the CLEAR User Facility CERN. All subsystems have been...
Space and phase resolved optical emission spectroscopy numerical simulations are employed to investigate the excitation dynamics of a radio-frequency-driven microatmospheric pressure plasma jet. Different power coupling modes can be identified by characteristic structures obtained from spectroscopic measurements. Numerical results 1-D fluid code with semikinetic treatment electrons show very good agreement experimental results.
Abstract Plasma-wakefield accelerators driven by intense particle beams promise to significantly reduce the size of future high-energy facilities. Such applications require with a well-controlled energy spectrum, which necessitates detailed tailoring plasma wakefield. Precise measurements effective wakefield structure are therefore essential for optimising acceleration process. Here we propose and demonstrate such measurement technique that enables femtosecond-level (15 fs) sampling...
<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> A large-scale atmospheric pressure plasma has been generated in helium, and the time-resolved optical electrical properties have shown to produce a homogeneous dielectric barrier discharge. Introducing tetraethyl orthosilicate as liquid aerosol into this produced clear, uniform, smooth polymerized coatings. Optical imaging studies that adding 1% oxygen gas mixture induced switch from filamentary...
Active plasma lenses have the potential to enable broad-ranging applications of plasma-based accelerators owing their compact design and radially symmetric kT/m-level focusing fields, facilitating beam-quality preservation beam transport. We report on direct measurement magnetic field gradients in active demonstrate impact emittance a charged particle beam. This is made possible by use well-characterized electron with 1.4 mm mrad normalized from conventional accelerator. Field up 823 T/m are...
The development of a plasma discharge at low voltage (200-600 V) in saline solution is characterized using fast and standard CCD camera imaging. Vapor formation, vapor collapse subsequent pressure wave propagation are observed. If, with increasing voltage, the total energy deposited kept approximately constant, sequence nature events similar but develop faster more reproducibly higher voltages. This attributed to slower temporal evolution layer lower voltages which means greater sensitivity...
The successful realization of high gain free-electron lasers has opened new possibilities to X-ray scientists for investigating matter in different states. availability unprecedented photon properties stimulated the development experimental techniques capable taking full advantage these options and started a virtuous collaboration between machine experts users improve further optimize generated pulses. Over recent years, this led several advanced laser (FEL) schemes tailor specific demands....