J. Strachan
A5109887081- Magnetic confinement fusion research
- Fusion materials and technologies
- Laser-Plasma Interactions and Diagnostics
- Superconducting Materials and Applications
- Particle accelerators and beam dynamics
- Nuclear Physics and Applications
- Nuclear reactor physics and engineering
- Plasma Diagnostics and Applications
- Ionosphere and magnetosphere dynamics
- Nuclear physics research studies
- Atomic and Molecular Physics
- High-Energy Particle Collisions Research
- Atomic and Subatomic Physics Research
- Laser-induced spectroscopy and plasma
- Particle Accelerators and Free-Electron Lasers
- X-ray Spectroscopy and Fluorescence Analysis
- Radiation Detection and Scintillator Technologies
- Particle Detector Development and Performance
- Gas Dynamics and Kinetic Theory
- High-pressure geophysics and materials
- Fluid Dynamics and Turbulent Flows
- Solar and Space Plasma Dynamics
- Spacecraft and Cryogenic Technologies
- Nuclear Materials and Properties
- Radiation Therapy and Dosimetry
Princeton Plasma Physics Laboratory
1999-2021
Royal Military Academy
2020
Princeton University
2005-2017
Daresbury Laboratory
2011-2015
Forschungszentrum Jülich
2002-2013
Sci-Tech Daresbury
2012
University of Cologne
2011
Culham Science Centre
2009-2011
Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro
2011
Istituto Nazionale di Fisica Nucleare
2011
Progress, since the ITER Physics Basis publication (ITER Editors et al 1999 Nucl. Fusion 39 2137–2664), in understanding processes that will determine properties of plasma edge and its interaction with material elements is described. Experimental areas where significant progress has taken place are energy transport scrape-off layer (SOL) particular anomalous scaling, particle SOL plays a major role diverted plasmas main-chamber elements, localized mode (ELM) deposition on mechanism for ELM...
Strong magnetohydrodynamic activity has been observed in PDX neutral-beam-heated discharges. It occurs for ${\ensuremath{\beta}}_{T}q>~0.045$ and is associated with a significant loss of fast ions drop neutron emission. As much as 20%-40% the beam heating power may be lost. The instability repetitive bursts oscillations \ensuremath{\le} 1 msec duration at 1-6-msec intervals. dubbed "fishbone instability" from its characteristic signature on Mirnov coils.
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 ${10}^{16}$...
It now appears feasible to deposit positrons (e+) in a tokamak plasma by injecting bursts of neutral positronium atoms (e+e−), which are then ionized the plasma. The annihilation time these is long compared with typical particle containment times. Thus subsequent transport can be studied monitoring dependence annihilation, gamma radiation produced when strike limiter. This paper discusses design such an experiment, kinds data obtained, and physics questions this experiment might address....
The issue of first wall and divertor target lifetime represents one the greatest challenges facing successful demonstration integrated tokamak burning plasma operation, even in case planned next step device, ITER, which will run at a relatively low duty cycle comparison to future fusion power plants. Material erosion by continuous or transient ion neutral impact, susbsequent transport released impurities through their deposition and/or eventual re-erosion constitute process migration. Its...
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 ratio of the runaway electron confinement to thermal energy is derived for tokamaks where both processes are determined by free streaming along stochastic magnetic field lines. enhanced at high energies due phase averaging over perturbations when drift surfaces displaced from surfaces. Comparison with experimental data LT-3, Ormak, PLT, ST, and TM-3 indicates that stochasticity may explain relative transport rates runaways energy.
An experiment at the Joint European Torus (JET) has demonstrated clear self-heating of a deuterium-tritium plasma by alpha particles produced in fusion reactions. The heating was identified scanning and neutral beam mixtures together from pure deuterium to nearly tritium 10.5 MW hot ion H mode. At an optimum mixture $(60\ifmmode\pm\else\textpm\fi{}20)%\mathrm{T}$, gain ( ${\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}P}_{\mathrm{fusion}}/{P}_{\mathrm{absorbed}}$) 0.65 showed clearly as...
Impurity injection in the JET ELMy H-mode regime has produced high-confinement, quasi-steady-state plasmas with densities close to Greenwald density. However, at large Ar densities, a sudden loss of confinement is observed. A possible correlation between and observed MHD phenomena, both core edge plasma, was considered. The degradation coincided impurity profile peaking following disappearance sawtooth activity. In addition, density analysis confirmed that central modes prevented peaking....
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...
An overview of JET experimental results in DT plasmas directly relevant to ITER modes operation is presented. Experiments D:T mixtures varying from 100:0 10:90 and those carried out hydrogen show that the H mode threshold power has an approximately inverse isotope mass dependence. Matching some key dimensionless parameters values, similarity experiments with shape safety factor q global energy confinement time practically independent isotopic (~A0.03±0.08), where A atomic hydrogenic species....
The d(d,p)t and d(d,n) 3 He fusion reactions produce 1 MeV tritons 0.8 ions which can subsequently undergo d(t, n) a d( He,p) reactions.The magnitude of this triton 3He ion 'burn-up' was measured on the PLT PDX tokamaks by detection 14 neutron 15 proton emission.In discharges with B,j>> 2 T, ^e burn-up is consistent (within factor three) predictions based classical theories confinement slowing down.In weaker toroidal fields but constant plasma current, both fell more than ten so that...
The EDGE2D-EIRENE code is applied for simulation of divertor detachment during matched density ramp experiments in high triangularity, L-mode plasmas both JET-Carbon (JET-C) and JET-ITER-Like Wall (JET-ILW). runs without drifts includes either C or Be as impurity, but not W, assuming that the W targets have been coated with via main chamber migration. simulations reproduce reasonably well observed particle flux raised JET-C JET-ILW can better match experimental in-out target power asymmetry...
A large “notch,” or non-monotonic feature, appears in measured toroidal velocity profiles of the carbon impurity Tokamak Fusion Test Reactor (TFTR) [Plasma Phys. Controlled 26, 11 (1984)], centered near radius strongest ion temperature gradient. This is explained as a consequence radial momentum transport dominated by anomalous diffusion together with parallel heat friction on ions arising from hydrogenic neoclassical flow. The profile species predicted to be monotonic, measurements...
Results from recent experiments to study the effects of divertor geometry and increased plasma shaping on L–H transition threshold JET are reported. Equivalent septum configurations run with new replacement plate (SRP) in MkII Gas Box have shown that presence lowers power threshold, Pth, by 20%. For X-point virtual top distances less than 6 cm, SRP plasmas also demonstrate a significant decrease Pth pedestal electron temperature, Te reduced height. Although, plasma's remains above septum,...
ELMy H-modes in helium-4 plasmas provide valuable information on H-mode physics as well a possible early low activation operational phase for next-step tokamaks, such ITER. With this mind, series of experiments were performed JET with pure NBI auxiliary heating (up to 12 MW). A set produced, both the Type I ELM regime and second regime, which showed characteristics similar deuterium III but reverse frequency dependence power. Sawteeth also observed, had behaviour those seen deuterium....
The 2.5 MeV neutron emission from the beam-target d(d, n)3He fusion reaction has been examined for all PDX deuterium plasmas which were heated by neutral beams. magnitude of was found to scale classically and increase with as expected when electron drag is primary energy degradation mechanism. time evolution through fishbone events measured used determine confinement properties energetic beam ions. Many experimental results are predicted Mode Particle Pumping Theory.
Tritium is produced in deuterium discharges the Princeton Large Torus by reaction D($d$,$p$)T. These tritons undergo reactions D($t$,$n$)$^{4}\mathrm{He}$ creating 14-MeV neutrons which have been detected two independent techniques at a level of 1% 2.5-MeV from D($d$,$n$)$^{3}\mathrm{He}$. The magnitude neutron emission consistent with finite banana width, neoclassical predictions for confinement energetic tritons.
This paper addresses the issues of impurity behaviour during argon seeding experiments in JET, which and D2 have been simultaneously puffed ELMy H-mode discharges to reach high density regimes, maintaining good confinement properties throughout plasma discharge. The analysis is based mainly on a 1-D diffusion model, evaluates transport coefficients three experimental scenarios.
Recent progress towards obtaining high density and confinement in JET as required for the ITER reference scenario at Q = 10 is summarized. Plasmas with simultaneous H98(y,2) 1 densities up to n/nGW~1 are now routinely obtained. This has been possible (i) by using plasmas (δ~0.5) medium (δ~0.3-0.4) triangularity sufficient heating power maintain Type I ELMs, (ii) impurity seeded low (δ⩽0.2) triangularity, (iii) an optimized pellet injection sequence, maintaining energy raising density, (iv)...