K. W. Hill
A5050616793- Magnetic confinement fusion research
- X-ray Spectroscopy and Fluorescence Analysis
- Fusion materials and technologies
- Laser-Plasma Interactions and Diagnostics
- Atomic and Molecular Physics
- Nuclear Physics and Applications
- Laser-induced spectroscopy and plasma
- Particle accelerators and beam dynamics
- Plasma Diagnostics and Applications
- Ionosphere and magnetosphere dynamics
- Superconducting Materials and Applications
- Advanced X-ray Imaging Techniques
- High-pressure geophysics and materials
- Atomic and Subatomic Physics Research
- X-ray Diffraction in Crystallography
- Advanced X-ray and CT Imaging
- High-Energy Particle Collisions Research
- Nuclear reactor physics and engineering
- Ion-surface interactions and analysis
- Crystallography and Radiation Phenomena
- Particle physics theoretical and experimental studies
- Quantum Chromodynamics and Particle Interactions
- Semiconductor materials and devices
- Solar and Space Plasma Dynamics
- Electron and X-Ray Spectroscopy Techniques
Princeton Plasma Physics Laboratory
2015-2024
Princeton University
2008-2024
University of Colorado Boulder
2006-2024
Lawrence Livermore National Laboratory
1986-2021
University of Wisconsin–Madison
1986-2021
Mayo Clinic
2021
WinnMed
2021
Colorado State University
2021
The University of Tokyo
1991-2021
National Institutes for Quantum Science and Technology
2021
Neutral-beam heating of plasmas in the Tokamak Fusion Test Reactor at low preinjection densities [${n}_{e}$(0)\ensuremath{\simeq}${10}^{19}$ ${\mathrm{m}}^{\mathrm{\ensuremath{-}}3}$] were characterized by ${T}_{e}$(0)=6.5 keV, ${T}_{i}$(0)=20 ${n}_{e}$(0)=7\ifmmode\times\else\texttimes\fi{}${10}^{19}$ ${\mathrm{m}}^{\mathrm{\ensuremath{-}}3}$, ${\ensuremath{\tau}}_{E}$=170 msec, ${\ensuremath{\beta}}_{\mathrm{theta}}$=2, and a d(d,n${)}^{3}$He neutron emission rate ${10}^{16}$...
Simultaneous profile measurements of the toroidal rotation speed and ion temperature during unbalanced neutral beam injection in Tokamak Fusion Test Reactor show that momentum thermal diffusivities are comparable magnitude (${\mathrm{\ensuremath{\chi}}}_{\mathrm{\ensuremath{\varphi}}}$\ensuremath{\approxeq}1.5${\mathrm{\ensuremath{\chi}}}_{\mathrm{i}}$) vary similarly with plasma current minor radius. The correlation ${\mathrm{\ensuremath{\chi}}}_{\mathrm{\ensuremath{\varphi}}}$...
Neutral-beam--heated plasmas in TFTR show evidence of substantial non-Ohmically driven toroidal current, even for balanced beam momentum input. The observations are inconsistent with calculations including only Ohmic and beam-driven currents, presently can be matched by models the neoclassical bootstrap current.
Dielectronic satellite spectra of Fe XXV near 1.8500 \AA{} have been observed from PLT (Princeton Large Torus) tokamak plasma discharges for electron temperatures in the range 1.5 to 3 keV and an density 2\ifmmode\times\else\texttimes\fi{}${10}^{13}$ ${\mathrm{cm}}^{\ensuremath{-}3}$. The temperature was independently determined cyclotron radiation emitted by plasma. quality allows a detailed comparison with theoretical predictions, which is importance view diagnostic applications.
Wall conditioning in the Tokamak Fusion Test Reactor (TFTR) [K. M. McGuire et al., Phys. Plasmas 2, 2176 (1995)] by injection of lithium pellets into plasma has resulted large improvements deuterium–tritium fusion power production (up to 10.7 MW), Lawson triple product 1021 m−3 s keV), and energy confinement time 330 ms). The maximum current for access high-performance supershots been increased from 1.9 2.7 MA, leading stable operation at stored values greater than 5 MJ. amount on limiter...
A transport code (TRANSP) is used to simulate future deuterium-tritium (DT) experiments in TFTR.The simulations are derived from 14 TFTR DD discharges, and the modelling of one supershot discussed detail indicate degree accuracy TRANSP modelling.Fusion energy yields 01 particle parameters calculated, including profiles slowing down time, average energy, AlfvBn speed frequency.Two types simulation discussed.The main emphasis on DT equivalent, where an equal mix D T substituted for initial...
Peak fusion power production of 6.2\ifmmode\pm\else\textpm\fi{}0.4 MW has been achieved in TFTR plasmas heated by deuterium and tritium neutral beams at a total 29.5 MW. These have an inferred central alpha particle density 1.2\ifmmode\times\else\texttimes\fi{}${10}^{17}$ ${\mathrm{m}}^{\mathrm{\ensuremath{-}}3}$ without the appearance either disruptive magnetohydrodynamics events or detectable changes Alfv\'en wave activity. The measured loss rate energetic particles agreed with...
General plasma physics principles state that power flow Q(r) through a magnetic surface in tokamak should scale as Q(r)= {32π2Rr3Te2c nea/[eB (a2−r2)2]} F(ρ*,β,ν*,r/a,q,s,r/R,...) where the arguments of F are local, nondimensional parameters and gradients. This paper reports an experimental determination how varies with normalized gyroradius ρ*≡(2TeMi)1/2c/eBa collisionality ν*≡(R/r)3/2qRνe(me/ 2Te)1/2 for discharges prepared so other remain close to constant. Tokamak Fusion Test Reactor...
The use of high resolution x-ray crystal spectrometers to diagnose fusion plasmas has been limited by the poor spatial localization associated with chord integrated measurements. Taking advantage a new imaging spectrometer concept [M. Bitter et al., Rev. Sci. Instrum. 75, 3660 (2004)], and improvements in detector technology [Ch. Broennimann J. Synchrotron Radiat. 13, 120 (2006)], spatially resolving built installed on Alcator C-Mod tokamak. This instrument utilizes spherically bent quartz...
K\ensuremath{\alpha} x-ray spectra of heliumlike titanium, Ti xxi, from Tokamak Fusion Test Reactor (TFTR) plasmas have been observed with a high-resolution crystal spectrometer and used as diagnostic central plasma parameters. The data allow detailed comparison recent theoretical predictions for the xxi lines associated satellite spectrum in wavelength range 2.6000 to 2.6400 A\r{}. Improved values excitation rate coefficients resonance line, intercombination lines, forbidden new results on...
Experimental results from high-power neutral-beam-injection experiments on the Princeton Large Torus tokamak are reported. At highest beam powers (2.4 MW) and lowest plasma densities [${n}_{e}(0)=5\ifmmode\times\else\texttimes\fi{}{10}^{13}$ ${\mathrm{cm}}^{\ensuremath{-}3}$], ion temperatures of 6.5 keV achieved. The collisionality ${{\ensuremath{\nu}}_{i}}^{*}$ drops below 0.1 over much radial profile. Electron heating $\frac{\ensuremath{\Delta}{T}_{e}}{{T}_{e}}\ensuremath{\approx}50%$ has...
The time-scales for sawtooth repetition and heat pulse propagation are much longer (tens of milliseconds) in the large tokamak TFTR than previous, smaller tokamaks. This extended time-scale, coupled with more detailed diagnostics, has led us to revisit analysis as a method determine electron diffusivity χe plasma. A combination analytic computer solutions diffusion equation is used clarify previous work develop new methods determining χe. Direct comparison predicted pulses soft-X-ray ECE...
A new method of actively modifying the plasma-wall interaction was tested on Tokamak Fusion Test Reactor. laser used to introduce a directed lithium aerosol into discharge scrape-off layer. The introduced in this fashion ablated and migrated preferentially limiter contact points. This allowed be influenced situ real time by external means. Significant improvement energy confinement fusion neutron production rate as well reduction plasma Zeff have been documented neutral beam heated plasma....
After many years of fusion research, the conditions needed for a D–T reactor have been approached on Tokamak Fusion Test Reactor (TFTR) [Fusion Technol. 21, 1324 (1992)]. For first time unique phenomena present in plasma are now being studied laboratory plasma. The magnetic experiments to study plasmas using nearly equal concentrations deuterium and tritium carried out TFTR. At maximum power 10.7 MW, 39.5 MW neutral-beam heating, supershot discharge 6.7 high-βp following current rampdown....
High-resolution spectra of the Ly-${\ensuremath{\alpha}}_{1}$ and Ly-${\ensuremath{\alpha}}_{2}$ lines hydrogenlike titanium, Ti XXII, associated dielectronic satellites which are due to transitions $1snl\ensuremath{-}2pnl$ with $n\ensuremath{\ge}2$, have been observed from tokamak discharges auxiliary ion-cyclotron heating central electron temperatures 2 keV densities 8\ifmmode\times\else\texttimes\fi{} ${10}^{13}$ ${\mathrm{cm}}^{\ensuremath{-}3}$ on Princeton Large Torus (PLT). The data...
Ion-temperature results are deduced from Doppler-broadening measurements of the $K\ensuremath{\alpha}$ ($1s\ensuremath{-}2p$) resonance line emitted heliumlike iron impurity ions in hot central core PLT (Princeton Large Torus) tokamak discharges. The were performed using a high-resolution Bragg-crystal spectrometer with multiwire proportional counter.
The wavelengths of the transition 1s2pAr1s2${p}^{1}$${P}_{1}$\ensuremath{\rightarrow}1${s}^{2}$ $^{1}S_{0}$ in heliumlike potassium, scandium, titanium, vanadium, chromium, and iron have been measured with an experimental precision \ensuremath{\Delta}\ensuremath{\lambda}/\ensuremath{\lambda}\ensuremath{\approxeq}1/20 000. data typically agree within error bars recent theoretical predictions that include quantum electrodynamical corrections. However, comparison shows there are systematic...
High-resolution spectra of Fe xxv have been observed from Princeton Large Torus tokamak discharges and are used for a detailed comparison with theoretical predictions Bely-Dubau, Gabriel, Volont\'e the ($1{s}^{2}nl\ensuremath{-}1s2pnl$, $n>~3$) dielectronic satellites at 1.85 \AA{}. The theory predicts significant apparent broadening resonance lines high-$Z$ heliumlike ions in high-temperature plasmas due to capture electrons into outer atomic shells. experimental results good general agreement.
The core imaging x-ray spectrometer (CIXS) is one of several ITER diagnostic systems planned for measurements the central ion and electron temperature profiles toroidal poloidal rotation velocity profiles, Ti, Te, v, vθ respectively. based on precision determinations Doppler broadening centroid shift lines highly ionized heavy impurities using a curved Bragg crystal spectral disperser imager. In departure from earlier designs, CIXS employs novel geometry utilizing spherically bent crystals...
Spectra of the n=3 to n=2 transitions in neonlike silver emitted from Princeton Large Torus have been recorded with a high-resolution Bragg-crystal spectrometer. The measurements cover wavelength region 3.3--4.1 A\r{} and include forbidden 3p\ensuremath{\rightarrow}2p electric quadrupole lines. Transitions adjacent sodiumlike, magnesiumlike, aluminumlike charge states also observed identified. Ly-\ensuremath{\alpha} spectra hydrogenlike argon iron, K\ensuremath{\alpha} heliumlike argon,...
This research describes advancements in the spectral analysis and error propagation techniques associated with x-ray imaging crystal spectroscopy (XICS) that have enabled this diagnostic to be used accurately constrain particle, momentum, heat transport studies a tokamak for first time. Doppler tomography been extended include of statistical uncertainty due photon noise, effect non-uniform instrumental broadening as well flux surface variations impurity density. These methods deployed suite...
Research on the National Spherical Torus Experiment, NSTX, targets physics understanding needed for extrapolation to a steady-state ST Fusion Nuclear Science Facility, pilot plant, or DEMO. The unique operational space is leveraged test theories next-step tokamak operation, including ITER. Present research also examines implications coming device upgrade, NSTX-U. An energy confinement time, τE, scaling unified varied wall conditions exhibits strong improvement of BTτE with decreased electron...
The results from the investigation of neoclassical core transport and role radial electric field profile (Er) in first operational phase Wendelstein 7-X (W7-X) stellarator are presented. In plasmas, details Er expected to have a strong effect on both particle heat fluxes. Investigation is important understanding validation calculations. closely related perpendicular plasma flow (u⊥) through force balance equation. This allows be inferred measurements velocity, which can measured using x-ray...
The Tokamak Fusion Test Reactor (TFTR) (R. J. Hawryluk, to be published in Rev. Mod. Phys.) experiments on high-temperature plasmas, that culminated the study of deuterium–tritium D–T plasmas containing significant populations energetic alpha particles, spanned over two decades from conception completion. During design TFTR, key physics issues were magnetohydrodynamic (MHD) equilibrium and stability, plasma energy transport, impurity effects, reactivity. Energetic particle was given less...
Toroidal Alfvén eigenmodes are shown to be capable of inducing ripple trapping high-energy particles in tokamaks, causing intense localized particle loss. The effect has been observed TFTR [R. Hawryluk, Plasma Phys. Controlled Fusion 33, 1509 (1991)].