B. Stratton
A5021188887- Magnetic confinement fusion research
- Fusion materials and technologies
- Particle accelerators and beam dynamics
- Ionosphere and magnetosphere dynamics
- Laser-Plasma Interactions and Diagnostics
- Superconducting Materials and Applications
- Plasma Diagnostics and Applications
- X-ray Spectroscopy and Fluorescence Analysis
- Diamond and Carbon-based Materials Research
- Atomic and Molecular Physics
- Laser-induced spectroscopy and plasma
- Nuclear Physics and Applications
- Atomic and Subatomic Physics Research
- Spectroscopy and Laser Applications
- Solar and Space Plasma Dynamics
- Laser-Ablation Synthesis of Nanoparticles
- Carbon Nanotubes in Composites
- Nuclear reactor physics and engineering
- Advanced X-ray Imaging Techniques
- Advanced X-ray and CT Imaging
- Physics of Superconductivity and Magnetism
- Particle Accelerators and Free-Electron Lasers
- Metal and Thin Film Mechanics
- Laser Design and Applications
- Nuclear Materials and Properties
University of Georgia
2025
Princeton Plasma Physics Laboratory
2013-2024
University of Wisconsin–Madison
1989-2021
Mayo Clinic
2021
WinnMed
2021
National Institutes for Quantum Science and Technology
2021
Edgewood College
2021
The University of Tokyo
2021
Kyushu University
2021
Lawrence Livermore National Laboratory
2006-2018
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 ${10}^{16}$...
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...
Simultaneous current ramping and application of lower hybrid heating drive (LHCD) have produced a region with zero density within measurement errors in the core ( r/a< or =0.2) JET tokamak optimized shear discharges. The reduction is consistent simple physical explanation numerical simulations radial diffusion including effects LHCD. However, clamped at zero, indicating existence mechanism which prevents it from becoming negative.
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...
Alpha particle physics experiments were done on TFTR during its DT run from 1993 to 1997. These utilized several new alpha diagnostics and hundreds of discharges characterize the confinement wave-particle interactions. In general, results agreed with classical single model in MHD quiescent discharges. The loss due toroidal field ripple was identified some cases, low radial diffusivity inferred for high energy alphas consistent orbit averaging over small scale turbulence. Finally, observed...
The National Spherical Torus Experiment (NSTX) has undergone a major upgrade, and the NSTX Upgrade (NSTX-U) Project was completed in summer of 2015.NSTX-U first plasma subsequently achieved, diagnostic control systems have been commissioned, H-mode accessed, magnetic error fields identified mitigated, physics research campaign carried out.During ten run weeks operation, NSTX-U surpassed record pulse-durations toroidal (TF), high-performance ~1 MA plasmas comparable to best sustained near...
Cation-π complexes of the form UOx+(benzene) (x = 0, 1, 2) are produced by laser vaporization and cooled in a supersonic molecular beam. These ions mass selected studied with UV–visible photodissociation spectroscopy. Each these photodissociates elimination benzene ligand. Above an energetic threshold, absorption continuous, indicating high density strongly coupled electronic states. The thresholds for dissociation each three measured assigned as their respective bond energies. energies...
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...
Optimized shear (OS) experiments in JET can generate an internal transport barrier (ITB) during a high power heating phase early the plasma discharge. A strong link is generally observed between formation of and location integer q magnetic surface within low (s = r/q(dq/dr)) region plasma. However, if q-profile for such modified by applying lower hybrid current drive (LHCD) before main pulse, to provide reduced or negative core, ITBs be formed which does not exhibit any apparent association...
The fusion performance of JET plasmas can be enhanced by the generation internal transport barriers. influence theq-profile shape in local and global plasma has been investigated cases where core magnetic shear ranges from small positive to large negative. Internal barriers extending radii effective raising plasma. It is found that such tend generated more easily if q-profile contains a region negative shear. formation favoured neutral beam injection compared with ion cyclotron resonance...
Comprehensive non-invasive spectroscopic techniques and electrical measurements of the carbon arc revealed two distinguishable plasma synthesis regions in radial direction normal to axis. These regions, which are defined as core periphery, shown have very different compositions species with densities temperatures. The colder periphery is dominated by diatomic molecules (C2), minority composition hot core. differences due a highly non-uniform distribution current, mainly conducted through...
In JET, advanced tokamak research mainly focuses on plasmas with internal transport barriers (ITBs) that are strongly influenced by the current density profile. A previously developed optimized shear regime low magnetic in plasma centre has been extended to deeply negative configurations. High fusion performance wide ITBs obtained transiently central configuration: HIPB98(y,2) ∼ 1.9, βN = 2.4 at Ip 2.5 MA. At somewhat reduced performance, electron and ion have sustained full drive operation...
The major objective of the National Spherical Torus Experiment (NSTX) is to understand basic toroidal confinement physics at low aspect ratio and high βT in order advance spherical torus (ST) concept. In do this, NSTX utilizes up 7.5 MW neutral beam injection, 6 harmonic fast waves (HHFWs), it operates with plasma currents 1.5 MA elongations 2.6 a field 0.45 T. New facility, diagnostic modelling capabilities developed over past two years have enabled research team make significant progress...
Recent operation of the Tokamak Fusion Test Reactor (TFTR) [Plasma Phys. Controlled Nucl. Research 1, 51 (1986)] has produced plasma equilibria with values Λ≡βp eq+li/2 as large 7, εβp dia≡2μ0ε〈p⊥〉/〈〈Bp〉〉2 1.6, and Troyon normalized diamagnetic beta 26, 209 (1984); Lett. 110A, 29 (1985)], βNdia≡108〈βt⊥〉aB0/Ip 4.7. When dia≳1.25, a separatrix entered vacuum chamber, producing naturally diverted discharge that was sustained for many energy confinement times, τE. The largest stored were...
Measurements of the spatial structure transport coefficients ${\mathrm{He}}^{2+}$ on Tokamak Fusion Test Reactor is reported. profiles were measured using charge-exchange spectroscopy after a helium puff into corotating L-mode plasmas. Modeling shows that diffusivity about 10 ${\mathrm{m}}^{2}$/s near plasma edge and drops to below 1 inside q=1 surface. The convective velocity ranges from 1--3 m/s 20--40 edge. order ion momentum thermal greater than electron diffusivity.
Circular-limiter H modes are obtained on the TFTR tokamak during high-power neutral-beam heating. The transition is usually from supershot to mode rather than usual L transition, and thus in a low-recycling environment with core fueling mainly heating beams. As result, density pressure profiles highly peaked at center. global confinement time ${\mathrm{\ensuremath{\tau}}}_{\mathit{E}}$ enhanced over L-mode scaling by up \ensuremath{\approxeq}2.5 times. onset of edge-localized MHD shortly...
The TFTR tokamak has reached its original machine design specifications (Ip=2.5 MA and BT=5.2 T). Recently, the D degrees neutral beam heating power been increased to 6.3 MW. By operating at low plasma current (Ip approximately=0.8 MA) density (ne approximately=1*1019 m-3), high ion temperatures (9+or-2 keV) rotation speeds (7*105 m/s) have achieved during injection. At opposite extreme, pellet injection into plasmas used increase line-average 8*1019 m-3 central 1.6*1020 m-3. This wide range...
In optimized shear plasmas in the Joint European Torus [P. H. Rebut and B. E. Keen, Fusion Technol. 11, 13 (1987)], safety factor (q) profiles with negative magnetic are produced by applying lower hybrid (LH) waves during plasma current ramp-up phase. These produce a barrier to electron energy transport. The radius at which is located increases LH wave power. When heated high power from ion cyclotron resonance heating neutral beam injection, they can additionally transient internal transport...
A new type of high-resolution x-ray imaging crystal spectrometer is being developed to measure ion and electron temperature profiles in tokamak plasmas. The instrument particularly valuable for diagnosing plasmas with purely ohmic heating rf heating, since it does not require the injection a neutral beam—although can also be used diagnosis neutral-beam heated consists spherically bent quartz two-dimensional position-sensitive detector. It records spectra helium-like argon (or krypton) from...
An adjusted form of thermionic emission is applied to calculate emitted current from laser-heated nanoparticles and interpret time-resolved laser-induced incandescence (TR-LII) signals. This predicts significantly lower values compared the commonly used Richardson-Dushman equation, since buildup positive charge in a nanoparticle increases energy barrier for further electrons. Thermionic influences particle's balance which can influence TR-LII Additionally, reports suggest that induce...
This article describes the overall design of Joint European Torus (JET) motional Stark effect (MSE) diagnostic. The principle this diagnostic has been proven on other tokamaks (TFTR and DIII-D) but its implementation JET involves specific difficulties associated with optical access neutral beam geometry. solutions adopted for problem include use a novel “Air Amici” prism deviation low Verdet coefficient glass relay optics. MSE signals from different sources are distinguished by their Doppler...
Measurements of the toroidal rotation speed vφ(r) driven by neutral beam injection in tokamak plasmas and, particular, simultaneous profile measurements vφ, Ti, Te, and ne, have provided new insights into nature anomalous transport tokamaks. Low-recycling heated with unidirectional exhibit a strong correlation among local diffusivities, χφ≊χi&gt;χe. Recent confirmed similar behavior broad-density L-mode plasmas. These results are consistent conjecture that electrostatic turbulence is...
The National Spherical Torus Experiment (NSTX) has made considerable progress in advancing the scientific understanding of high performance long-pulse plasmas needed for future spherical torus (ST) devices and ITER.Plasma durations up to 1.6 s (five current redistribution times) have been achieved at plasma currents 0.7 MA with non-inductive fractions above 65% while simultaneously achieving β T N values 17% 5.7 (%m -1 ), respectively.A newly available motional Stark effect diagnostic...