A5103137861- Particle Accelerators and Free-Electron Lasers
- Laser-Matter Interactions and Applications
- Particle accelerators and beam dynamics
- Sensor Technology and Measurement Systems
- Neural Networks and Applications
- Semiconductor Lasers and Optical Devices
- Microwave Engineering and Waveguides
- Advanced Electron Microscopy Techniques and Applications
- Electric Motor Design and Analysis
- Particle Detector Development and Performance
- Gyrotron and Vacuum Electronics Research
- Advanced Fiber Laser Technologies
- Superconducting Materials and Applications
- Laser-Plasma Interactions and Diagnostics
- Magnetic confinement fusion research
- Ionosphere and magnetosphere dynamics
- Mass Spectrometry Techniques and Applications
- Ion-surface interactions and analysis
- Laser-induced spectroscopy and plasma
- Force Microscopy Techniques and Applications
- Fusion materials and technologies
- Radiation Detection and Scintillator Technologies
- Plasma Diagnostics and Applications
- Near-Field Optical Microscopy
- Global Energy and Sustainability Research
Alpha Omega Electromagnetics (United States)
2019-2020
Canadian Standards Association
2018-2020
Office of International Affairs
2019-2020
University of Nottingham
2018-2020
Institute of Electrical and Electronics Engineers
2017-2020
Max Planck Institute of Quantum Optics
2012-2020
Cornell University
1973-2020
Ludwig-Maximilians-Universität München
2020
University of Bologna
2020
Institut national de recherche en informatique et en automatique
2019-2020
The principal raw material of modern U.S. agriculture is fossil fuel, whereas the labor input relatively small (about 9 hours per crop acre). As dependent upon energy, production costs will also soar when fuel increase two- to fivefold. A return 2.8 kcal corn 1 may then be uneconomical. Green revolution uses high energy technology, especially with respect fertilizers and pesticides. While one not doubt sincerity effort share its agricultural technology so that rest world can live eat as it...
We present a nano-scale photoelectron source, optimized for ultrashort pulse durations and well-suited time-resolved diffraction advanced laser acceleration experiments. A tungsten tip of several-ten-nanometers diameter mounted in suppressor-extractor electrode configuration allows the generation 30 keV electron pulses with an estimated duration 9 fs (standard deviation; 21 full width at half maximum) gun exit. infer from particle tracking simulations, which are excellent agreement...
We demonstrate coherent control of multiphoton and above-threshold photoemission from a single solid-state nanoemitter driven by fundamental weak second harmonic laser pulse. Depending on the relative phase two pulses, electron emission is modulated with contrast oscillating current signal up to 94%. Electron spectra reveal that all observed photon orders are affected simultaneously similarly. confirm takes place within 10 fs. Accompanying simulations indicate modulation its large results...
A stretched flexible hollow fiber is proposed as a waveguide in high-energy pulse compressors. This approach leads to superior straightness virtually independent of the length. It particularly well suited for fibers with inner diameters much larger than wavelength, where main limitation length losses due undesired bending. The construction issues are discussed, and quality proved by comparing experimental data calculations showing that transmission reaches theoretical limit emerging beam...
We present a simple and efficient concept for the generation of ultrashort infrared pulses with passively stabilized carrier-envelope phase at 100 kHz repetition rate. The central wavelength is tunable between 1.6 2.0 µm pulse durations 8.2 12.8 fs, corresponding to sub-two-cycle duration over whole tuning range. Pulse energies up 145 nJ are achieved. As first application we measure high nonlinearity multiphoton photoemission from nanoscale metal tip.
We present a new method of measuring optical near-fields within ~1 nm metal surface, based on rescattering photoemitted electrons. With this method, we precisely measure the field enhancement factor for tungsten and gold nanotips as function tip radius. The agreement with Maxwell simulations is very good. Further yield map all materials, which shows that at are governed by geometric effect under most conditions, while plasmon resonances play only minor role. Last, consider implications our...
High order harmonics generated at relativistic intensities have long been recognized as a route to the most powerful extreme ultraviolet pulses. Reliably generating isolated attosecond pulses requires gating only single dominant optical cycle, but techniques developed for lower power lasers not readily transferable. We present novel method temporally gate pulse trains by combining noncollinear and polarization gating. This scheme uses split beam configuration which allows be implemented high...
We report on the observation of incoherent Cherenkov radiation emitted by a 5.3 GeV positron beam circulating in Cornell electron-positron storage ring as passes close vicinity surface fused silica radiator (i.e., at distance larger than 0.8 mm). The shape was designed order to send photons towards detector, consisting compact optical system equipped with an intensified camera. allows both measurements 2D images and angular distribution including polarization study. corresponding light...
Self-probing of atoms or molecules by their own electrons is a powerful tool for exploring structural dynamics with high spatial and temporal resolution. Spectra from high-harmonic generation photoelectron rescattering reveal the quantities interest, such as electronic structure system under scrutiny. Recently, we have observed effect at solids, in particular metal nanotips. Here use self-probing approach order to investigate an inherent nano-scale systems: laser light incident on nanotips...
Recent advances in attosecond science combination with the well-established techniques of nanofabrication have led to new research field nanophysics. One central goal is characterization and manipulation electromagnetic fields on nanometer scale. This has so far remained challenging both theoretically experimentally. major obstacle inhomogeneity electric fields. We present a general model below, which allows description streaking near It classification into different regimes as well...
Transient near fields around metallic nanotips drive many applications, including the generation of ultrafast electron pulses and their use in microscopy. We have investigated emission from a gold nanotip driven by midinfrared few-cycle laser pulses. identify low-energy peak kinetic energy spectrum study its shift to higher energies with increasing intensities 1.7 $8.9\ifmmode\times\else\texttimes\fi{}{10}^{11}\phantom{\rule{0.28em}{0ex}}\mathrm{W}/{\mathrm{cm}}^{2}$. The experimental...
In this article we present coherent control of above-threshold photoemission from a tungsten nanotip achieving nearly perfect modulation. Depending on the pulse delay between fundamental (1560 nm) and second harmonic (780 pulses femtosecond fiber laser at nanotip, electron emission is significantly enhanced or depressed during temporal overlap. Electron studied as function delay, optical near-field intensities, DC bias field, final photoelectron energy. Under optimized conditions modulation...
A heat load experiment was carried out with a new kind of probe for the detection damage caused by runaway electrons. The inserted into plasma edge tokamak TEXTOR during an induced disruption. damages, disruption generated electrons in material, are evaluated metallographical and thermogravimetrical methods. In comparison 3D Geant4 code based Monte Carlo simulations runaways information about energy spectrum radial decay beam behind limiter deduced. results good agreement exponential...
Calorimetric measurements of the total runaway electron energy are carried out using a reciprocating probe during induced TEXTOR disruptions. A comparison with inferred from spectra, which measured scintillator probe, is used as an independent check results. typical current 100 kA at contains 30 to 35 kJ energy. The dependencies on current, radial position, toroidal magnetic field and predisruptive plasma studied. conversion efficiency into calculated be up 26%.
Chaotic transport of runaway electrons in a toroidal system the presence weak small-scale magnetic turbulent field with wide mode spectrum is studied. Using fast running mapping, radial profiles diffusion coefficients are calculated. It found that at large Kubo numbers chaotic described by fractal-like dependence reduced or zero values near low-order rational drift surfaces which form barriers. The latter can be one main reasons improved confinement tokamaks. One expect this effect may lead...
This paper presents experimental measurements of the femtosecond timescale generation magnetic field fluctuations exceeding 1 kT in relativistic laser-solid interaction, using a probe electron beam generated laser wakefield accelerator. Three-dimensional particle-in-cell simulations demonstrate that such originate from current filamentation instability arising at submicron scales around irradiated target surface, and they grow few tens femtoseconds to amplitudes strong enough broaden angular...
The status of plans for an energy-recovery linac (ERL) X-ray facility at Cornell University are described. currently operates the high energy synchrotron source (CHESS) CESR ring. ERL is planned to be extension that ring by a 5-GeV superconducting c.w. linac. very small electron-beam emittances would produce considerably better than any existing storage-ring light source. design presented has allow non-destructive transport these emittances. It includes up 18 beamlines specific areas...
Abstract The losses of runaway electrons due to magnetic perturbation fields are measured applying a scintillator probe during the flat top phases purely ohmically heated low density discharges. effects well-defined amplitudes on temporal evolution and spectral properties runaways analyzed. transport towards plasma edge is described by model which takes turbulences field into account. Using an asymptotic theory, orbits as well radially energy dependent coefficients for calculated. A...
Novel observations of the burst-like runaway electron losses in tokamak disruptions are reported. The bursts temporally resolved and first-time measurements corresponding energy spectra presented. A characteristic shape burst to changes found. content conversion predisruptive magnetic estimated. radial decay runaways can be approximated by an exponential distribution. Deriving from measurements, resistive tearing modes or kink suggested trigger formation bursts.