A5044518786- Atomic and Molecular Physics
- Mass Spectrometry Techniques and Applications
- Advanced Chemical Physics Studies
- Magnetic confinement fusion research
- Fusion materials and technologies
- X-ray Spectroscopy and Fluorescence Analysis
- Laser-induced spectroscopy and plasma
- Ion-surface interactions and analysis
- Fullerene Chemistry and Applications
- Laser Design and Applications
- Diamond and Carbon-based Materials Research
- Superconducting Materials and Applications
- Spectroscopy and Quantum Chemical Studies
- Photoreceptor and optogenetics research
- Electron and X-Ray Spectroscopy Techniques
- Cold Atom Physics and Bose-Einstein Condensates
- Laser-Matter Interactions and Applications
- Particle accelerators and beam dynamics
- Molecular Junctions and Nanostructures
- Analytical Chemistry and Sensors
- Graphene research and applications
- Molecular spectroscopy and chirality
- Synthesis and Reactions of Organic Compounds
- Planetary Science and Exploration
- Quantum optics and atomic interactions
Culham Science Centre
2021-2024
Culham Centre for Fusion Energy
2021-2024
Diamond Light Source
2024
United Kingdom Atomic Energy Authority
2022-2023
University of Nevada, Reno
2004-2014
Queen's University Belfast
2002-2012
State University of New York
1979
Abstract The JET hybrid scenario has been developed from low plasma current carbon wall discharges to the record-breaking Deuterium-Tritium plasmas obtained in 2021 with ITER-like Be/W wall. development started pure Deuterium refinement of current, and toroidal magnetic field choices succeeded solving heat load challenges arising 37 MW injected power ITER like environment, keeping radiation edge core controlled, avoiding MHD instabilities reaching high neutron rates. have re-run Tritium...
Neutral C60 is well known to exhibit a giant resonance in its photon absorption spectrum near 20 eV. This associated with surface plasmon, where delocalized electrons oscillate as whole relative the ionic cage. Absolute photoionization cross-section measurements for C+60, C2+60, and C3+60 ions 17-75 eV energy range show an additional 40 Time-dependent density functional calculations confirm collective nature of this feature, which characterized dipole-excited volume plasmon made possible by...
Time-of-flight-based mass analysis of charged water fragments have been used to measure the dissociative and nondissociative reaction pathways formed during collisions with $15\phantom{\rule{0.3em}{0ex}}\text{to}\phantom{\rule{0.3em}{0ex}}100\phantom{\rule{0.3em}{0ex}}\mathrm{keV}$ $500\phantom{\rule{0.3em}{0ex}}\text{to}\phantom{\rule{0.3em}{0ex}}3500\phantom{\rule{0.3em}{0ex}}\mathrm{keV}$ ${\mathrm{H}}^{+}$ projectiles...
Abstract This paper reports the first experiment carried out in deuterium–tritium addressing integration of a radiative divertor for heat-load control with good confinement. Neon seeding was time D–T plasma as part second campaign JET its Be/W wall environment. The technical difficulties linked to re-ionisation heat load are reported T and D–T. compares impact neon on plasmas their D counterpart detachment, localisation radiation, scrape-off profiles, pedestal structure, edge localised modes global
Lifetimes for K-shell vacancy states in atomic carbon have been determined by measurement of the natural linewidth 1s → 2p photoexcited C + ions. The produced photoionization are identical to those photoexcitation a ion: 1s2s 2 22 D, P, and S autoionizing occur both cases. These stabilize emission an electron produce 2+ Measurements reported lifetime P :6 .3± 0.9 fs, 11.2 ± 1.1 fs 5.9 1.3 respectively. Knowledge such lifetimes is important comparative studies Kshell vacancies...
Absolute cross sections for the K-shell photoionization of ground-state Li-like carbon [C3+(1s22s 2S)] ions were measured by employing ion–photon merged-beams technique at Advanced Light Source. The energy ranges 299.8–300.15 eV, 303.29–303.58 eV and 335.61–337.57 [1s(2s2p)3P]2P, [1s(2s2p)1P]2P [(1s2s)3S 3p]2P resonances, respectively, investigated using resolving powers up to 6000. autoionization linewidth resonance was be 27 ± 5 meV compares favourably with a theoretical result 26 obtained...
Absolute cross-section measurements for resonant double photoexcitation of Li+ ions followed by autoionization have been performed at high resolution in the photon energy range from 148 eV, just below (2s2p, 2(0, 1)n+) resonance, to 198 eV (the region ionization threshold). The made using photon–ion merged-beam endstation Advanced Light Source, Lawrence Berkeley National Laboratory, USA. absolute show excellent agreement with theoretical results R-matrix plus pseudo-state (RMPS) method....
Time-of-flight mass spectrometry was used to investigate fragmentation and energy transfer processes in water by C ions at the distal part of Bragg peak. Measurements positive ion fragments from ionization, electron capture, loss, transfer-loss loss-ionization channels have allowed us for first time (a) obtain a quantitative determination lost (b) show that total fragment production has much flatter profile with projectile than would be expected if radical formation assumed follow...
Measurements of the ion currents to and plasma conditions at low-field side (LFS) divertor target plate in low-confinement mode plasmas JET ITER-like wall materials configuration show that core density required detach LFS is independent hydrogenic species protium, deuterium tritium, a 40 %/60 % deuterium–tritium mixture. This observation applies with strike line connected horizontal part chosen because its superior diagnostic coverage. The finding operational status cryogenic pump. electron...
Absolute cross-section measurements for K-shell photoionization of Be-like C2+ ions have been performed in the photon energy range 292–325 eV. These made using photon–ion merged-beam endstation at Advanced Light Source, Lawrence Berkeley National Laboratory. compared with theoretical results from R-matrix method indicate that primary ion beam consisted 62% ground-state (1s22s2 1S) and 38% metastable state (1s22s2p 3Po) ions. Reasonable agreement is seen between theory experiment absolute...
Absolute cross sections for the K-shell photoionization of ground-state Li-like boron [B2 +(1s22s 2S)] ions were measured by employing ion–photon merged-beams technique at Advanced Light Source synchrotron radiation facility. The energy ranges 197.5–200.5 eV, and 201.9–202.1 eV [1s(2s2p)3P]2Po [1s(2s2p)1P] 2Po resonances, respectively, investigated using resolving powers up to 17 600. range experiments was extended about 238.2 yielding energies most prominent [1s(2ℓ nℓ')]2Po resonances with...
Abstract Since the installation of ITER-like wall on JET tokamak, visible emission from a broad range tungsten charge states has complicated plasma ion temperature and toroidal rotation measurements. A plethora exchange transitions, ions up to W 56+ , 21 suspected magnetic dipole transitions have been observed. In particular 39+ 46+ contaminates long-established carbon measurement at 529 nm. Fortunately wavelength relative intensity lines is predictable their influence can be mitigated when...
The electron impact dissociative double-ionization cross sections for ${\mathrm{H}}_{2}\mathrm{O}$ between 45 and $1500\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ have been measured using time of flight mass spectrometry. energy dependence the ${\mathrm{H}}^{+}+\mathrm{O}{\mathrm{H}}^{+}$ ${\mathrm{H}}^{+}+{\mathrm{O}}^{+}$ ion pair production indicate that Auger-like autoionization following a vacancy in $2{a}_{1}$ molecular orbital is main double ionization channel at high velocities. In...
Absolute cross sections for the K-shell photoionization of Be-like boron ions were measured with ion–photon merged-beams technique at Advanced Light Source synchrotron radiation facility. High-resolution spectroscopy E/ΔE up to 8800 (ΔE ∼ 22 meV) covered energy ranges 193.7–194.7 eV and 209–215 eV. Lifetimes strongest resonances are determined relative uncertainties down approximately 4% broadest resonance. The resonance strengths consistent 60% 1s22s2 1S ground-state 40% 1s22s2p 3Po...
Negative fragment ion formation from SF6 has been studied using synchrotron radiation within the energy range 20-205 eV. The ions F-, F2-, S- and SF- have observed. It is shown that shape resonance unoccupied valence orbitals play an important role in negative after photoexcitation of inner S 2p electrons. yields a core electron show evidence localization around central atom. F- F2- outer regions not only confirm pair occurs via predissociating Rydberg states but also demonstrate, for first...
Photoionization and electron-impact ionization of ${\mathrm{Xe}}^{3+}$ ions in the region $4d$ inner-shell excitation-autoionization have been studied using interacting-beam spectroscopic techniques. Absolute cross sections for photoionization obtained spectrum has normalized to previously published absolute data. The spectra show large contributions from $4d\ensuremath{\rightarrow}nf$ processes compared lower charge states Xe due significant collapse $nf$ wave functions into ion core as...
A Reply to the Comment by A. V. Korol and Solov’yov.Received 21 December 2006DOI:https://doi.org/10.1103/PhysRevLett.98.179602©2007 American Physical Society
Photoionization of triply charged titanium ions was investigated using the merged photon–ion beam technique at a synchrotron light source. The experimental photon energy range 42.6–49.4 eV encompasses threshold for photoionization Ti3+(3p6 3d2 D3/2) ground-state 43.267 eV. Prominent resonance features due to 3p → 3d and 4s excitations are observed with strongest one being 'giant' 3p5(3d23F)2F dipole which has width 1.5 Since it is located only 0.2 above ionization cut-off this in...
Cross sections for single photoionization of Fe${}^{3+}$, Fe${}^{5+}$, and Fe${}^{7+}$ ions were measured at spectral resolutions 0.04, 0.15, 0.13 eV, respectively, by merging mass- charge-selected ion beams with a beam monochromatized synchrotron undulator radiation. The measurements span photon energy ranges beginning the ionization thresholds extending several tens electron volts to include most important resonant contributions due $3p$--$\mathit{nd}$ transitions autoionizing states....
Photoion-pair formation in H2O and D2O has been studied using synchrotron radiation within the energy range 15–50 eV. Appearance potentials for of O−, OH− H− have determined coincide with their thermochemical thresholds. Above threshold it is shown that superexcited states play an important role polar photodissociation process. Substantial isotope effects observed.
Absolute cross-section measurements for resonant double photoexcitation of Li+ions followed by autoionization have been performed at high resolution in the photon energy range from 148 eV, just below (2s2p, 2(0,1)+2) resonance to 198 eV (the region ionization threshold). The made using photon-ion merged-beam endstation Advanced Light Source, Lawrence Berkeley National Laboratory, USA. absolute show excellent agreement with theoretical results R-matrix plus pseudo-state (RMPS) method.
The molecular and dissociative photoionization of C2H6 has been studied using synchrotron radiation within the energy range 11-40 eV. Positive negative photoion mass spectra threshold photoelectron have obtained. These show that superexcited states, which can decay through ion pair formation, play an important role in photodissociative ionization process. positive yield curves display significant hitherto unobserved structures, are unrelated to those present spectra.