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Observation Of Sawtooth Redistribution Of Nonthermal Confined Alpha Particles In Tftr D T Discharges
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Book Synopsis Observation of Sawtooth Redistribution of Nonthermal, Confined Alpha Particles in TFTR D-T Discharges by : B. C. Stratton
Download or read book Observation of Sawtooth Redistribution of Nonthermal, Confined Alpha Particles in TFTR D-T Discharges written by B. C. Stratton and published by . This book was released on 1996 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Observation of Sawtooth Redistribution of Nonthermal, Confined Alpha Particles in TFTR D-T Discharges by : B. C. Stratton
Download or read book Observation of Sawtooth Redistribution of Nonthermal, Confined Alpha Particles in TFTR D-T Discharges written by B. C. Stratton and published by . This book was released on 1996 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Sawtooth Mixing of Alpha Particles in TFTR D-T Plasmas by :
Download or read book Sawtooth Mixing of Alpha Particles in TFTR D-T Plasmas written by and published by . This book was released on 1996 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: Radially resolved confined alpha particle energy and density distributions are routinely measured on TFTR using two diagnostics: PCX and [alpha]-CHERS. The Pellet Charge-eXchange (PCX) diagnostic uses the ablation cloud formed by an impurity pellet (Li or B) for neutralization of the alphas followed by analysis of the escaping helium neutrals. PCX detects deeply trapped alpha particles in the energy range 0.5 - 3.8 MeV. The [alpha]-CHERS technique, were the alpha signal is excited by charge-exchange between alphas and the deuterium atoms of one of the heating beams and appears as a wing on the He 468.6 nm line, detects mainly passing alphas in the range of 0.15 - 0.7 MeV. Studies of alpha losses during DT experiments on TFTR have also been conducted using lost alpha detectors located on the walls of the plasma chamber. All of these diagnostics were used for investigating the influence of sawtooth crashes on alphas in high power D-T discharges in TFTR. Both PCX and [alpha]-CHERS measurements show a strong depletion of the alpha core density and transport of trapped alphas radially outwards well beyond q = 1 surface after a sawtooth crash. Lost alpha detectors measure bursts of alpha loss of the previously confined alphas (
Book Synopsis Confined Nonthermal Alpha Distribution and Transport Measurements in D-T Plasmas on TFTR by : George R. McKee
Download or read book Confined Nonthermal Alpha Distribution and Transport Measurements in D-T Plasmas on TFTR written by George R. McKee and published by . This book was released on 1995 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nuclear Fusion written by and published by . This book was released on 2000 with total page 786 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Sawtooth Mixing of Alpha Particles in TFTR D-T Plasmas by : Mikhail Petrovich Petrov
Download or read book Sawtooth Mixing of Alpha Particles in TFTR D-T Plasmas written by Mikhail Petrovich Petrov and published by . This book was released on 1996 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Modeling of A-particle Redistribution by Sawteeth in TFTR Using FPPT Code by :
Download or read book Modeling of A-particle Redistribution by Sawteeth in TFTR Using FPPT Code written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Results from recent DT experiments on TFTR to measure the radial density profiles of fast confined well trapped[alpha]-particles using the Pellet Charge eXchange (PCX) diagnostic[PETROV M.P., et. al. Nucl. Fusion, 35 (1995) 1437] indicate that sawtooth oscillations produce a significant broadening of the trapped alpha radial density profiles.' Conventional models consistent with measured sawtooth effects on passing particles do not provide satisfactory simulations of the trapped particle mixing measured by PCX diagnostic. We propose a different mechanism for fast particle mixing during the sawtooth crash to explain the trapped[alpha]-particle density profile broadening after the crash. The model is based on the fast particle orbit averaged toroidal drift in a perturbed helical electric field with an adjustable absolute value. Such a drift of the fast particles results in a change of their energy and a redistribution in phase space. The energy redistribution is shown to obey the diffusion equation, while the redistribution in toroidal momentum P[var-phi] (or in minor radius) is assumed stochastic with large diffusion coefficient and was taken flat. The distribution function in a pre- sawtooth plasma and its evolution in a post-sawtooth crash plasma is simulated using the Fokker-Planck Post-TRANSP (FPPT) processor code. It is shown that FPPT calculated[alpha]-particle distributions are consistent with TRANSP Monte-Carlo calculations. Comparison of FPPT results with Pellet Char eXchange (PCX) measurements shows good agreement for 9 both sawtooth free and sawtoothing plasmas.
Book Synopsis Measurements of Energetic Confined Alphas and Tritons on TFTR. by : S. S. Medley
Download or read book Measurements of Energetic Confined Alphas and Tritons on TFTR. written by S. S. Medley and published by . This book was released on 1995 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Aspects of Trapped Confined Alpha Physics on TFTR. by :
Download or read book Aspects of Trapped Confined Alpha Physics on TFTR. written by and published by . This book was released on 1996 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: The energy distributions and radial density profiles of the fast-confined trapped alpha particles in DT experiments on TFTR are being measured in the energy range 0.5 to 3.5 MeV using the Pellet Charge Exchange diagnostic developed in a collaboration involving General Atomics, the A.F. Ioffe Physical-Technical Institute, and the Princeton Plasma Physics Laboratory. A brief description of the measurement technique which involves active neutral particle analysis using the ablation cloud surrounding an injected lithium or pellet as the neutralizer is presented. In the core of quiescent TFTR discharges, measured alpha spectra are consistent with classical slowing down. Measured Doppler broadening of alphas near the birth energy is consistent with the effective temperature of interacting deuterium and tritium ions. Outside the core alpha energy spectra and density profiles are influenced by the magnetic field ripple and appear to be consistent with stochastic ripple diffusion. Sawtooth oscillations lead to the significant broadening of alpha density profiles. The experimental data are modeled using a Fokker-Planck Post TRANSP (FTTP) code which includes the effects of the classical slowing down, magnetic field ripple losses, and the sawtooth mixing of alpha particles. The comparison of the experimental data with the FPPT calculations shows that broadening of trapped alpha density profiles after the sawtooth crashes can be explained by the influence of poloidal electric field generated during the crashes.
Book Synopsis Simulation of [alpha]-particle Redistribution Due to Sawteeth on TFTR. by :
Download or read book Simulation of [alpha]-particle Redistribution Due to Sawteeth on TFTR. written by and published by . This book was released on 1996 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: In recent Deuterium-Tritium experiments on the Tokamak Fusion Test Reactor (TFTR), both the Pellet Charge Exchange (PCX) and the alpha Charge Exchange Recombination Spectroscopy ([alpha]-CHERS) diagnostics indicate that sawtooth oscillations can cause significant broadening of the fusion alpha radial density profile. The authors investigate this sawtooth mixing phenomenon by applying a Hamiltonian guiding center approach. A model of time evolution of the Kadomtsev-type sawtooth is constructed. The presence of more than one mode in the nonlinear stage of the sawtooth crash is necessary to cause significant broadening of the alpha density profile. Use of numerical equilibria allows us to perform detailed comparisons with TFTR experimental data. The results are in reasonable agreement with [alpha]-CHERS and show a broadening of alpha particles similar to that seen in PCX measurements.
Book Synopsis Overview of D-T Results from TFTR. by :
Download or read book Overview of D-T Results from TFTR. written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Experiments with plasmas having nearly equal concentrations of deuterium and tritium have been carried out on TFTR. To date, the maximum fusion power has been 10.7 MW, using 39.5 MW of neutral-beam heating, in a supershot discharge and 6.7 MW in a high-[beta][sub p] discharge following a current ramp-down. The fusion power density in the core of the plasma has reached 2.8 MWm[sup[minus]3], exceeding that expected in the International Thermonuclear Experimental Reactor (ITTER). The energy confinement time, [tau][sub E], is observed to increase in D-T, relative to D plasmas, by 20% and the n[sub i](O)[center-dot][tau][sub E] product by 55%. The improvement in thermal confinement is caused primarily by a decrease in ion heat conductivity in both supershot and limiter-H-mode discharges. Extensive lithium pellet injection increased the confinement time to 0.27 s and enabled higher current operation in both supershot and high-[beta][sub p] discharges. First measurements of the confined alpha particles have been performed and found to be in good agreement with TRANSP simulations assuming classical confinement. Measurements of the alpha ash profile have been compared with simulations using particle transport coefficients from helium gas puffing experiments. The loss of energetic alpha particles to a detector at the bottom of the vessel is well described by the first-orbit loss mechanism. No loss due to alpha-particle-driven instabilities has yet been observed. ICRF heating of a D-T plasma, using the second harmonic of tritium, has been demonstrated. D-T experiments on TFTR will continue both to explore the physics underlying the ITER design and to examine some of the physics issues associated with an advanced tokamak reactor.
Book Synopsis Confined Nonthermal Alpha Distribution and Transport Measurement in D-T Plasmas on TFTR by : George R. McKee
Download or read book Confined Nonthermal Alpha Distribution and Transport Measurement in D-T Plasmas on TFTR written by George R. McKee and published by . This book was released on 1995 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Confined Trapped-alpha Behavior in TFTR Deuterium-tritium Plasmas by :
Download or read book Confined Trapped-alpha Behavior in TFTR Deuterium-tritium Plasmas written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Confined trapped-alpha energy spectra and differential radial density profiles in TFTR D-T plasmas are obtained with the Pellet Charge-eXchange (PCX) diagnostic which measures high energy (E[sub[alpha]]= 0.5--3.5 MeV), trapped alphas (v[sub[parallel]]/v= - 0.048) at a single time slice ([Delta]t[approximately] 1 msec) with a spatial resolution of[Delta]r[approximately] 5 cm. Tritons produced in D-D plasmas and RF-driven ion tails (H, [sup 3]He or T) were also observed and energetic tritium ion tail measurements will be discussed. PCX alpha and triton energy spectra extending up to their birth energies were measured in the core of MHD-quiescent discharges where the expected classical slowing down and pitch angle scattering effects are not complicated by stochastic ripple diffusion and sawtooth activity. Both the shape of the measured alpha and triton energy distributions and their density ratios are in good agreement with TRANSP predictions, indicating that the PCX measurements are consistent with classical thermalization of the fusion-generated alphas and tritons. From calculations, these results set an upper limit on possible anomalous radial diffusion for trapped alphas of D[sub[alpha]][le] 0.01 m[sup 2]s[sup[minus]1]. Outside the core, where the trapped alphas are influenced by stochastic ripple diffusion effects, the PCX measurements are consistent with the functional dependence of the Goldston-White-Boozer stochastic ripple threshold on the alpha energy and the q-profile. In the presence of strong sawtooth activity, the PCX diagnostic observes significant redistribution of the alpha signal radial profile wherein alphas are depleted in the core and redistributed to well outside the q= 1 radius, but apparently not beyond the energy-dependent stochastic ripple loss boundary.
Book Synopsis Distributions of Alpha Particles Escaping to the Wall Because of Sawtooth Oscillations in TFTR. by : Ya. I. Kolesnichenko
Download or read book Distributions of Alpha Particles Escaping to the Wall Because of Sawtooth Oscillations in TFTR. written by Ya. I. Kolesnichenko and published by . This book was released on 1998 with total page 61 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis TF Ripple Loss of Alpha Particles in TFTR DT Experiments by : TFTR Team
Download or read book TF Ripple Loss of Alpha Particles in TFTR DT Experiments written by TFTR Team and published by . This book was released on 1995 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Alpha Particle Loss in TFTR Deuterium-tritium Plasmas with Reversed Magnetic Shear by :
Download or read book Alpha Particle Loss in TFTR Deuterium-tritium Plasmas with Reversed Magnetic Shear written by and published by . This book was released on 1997 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: The confinement and loss of fusion alpha particles are examined for reversed magnetic shear plasmas in TFTR. Such plasmas, with high central q and non-monotonic q profiles can exhibit remarkably reduced energy and particle transport of the thermal ions. However, these same conditions are theoretically predicted to produce high levels of stochastic ripple loss of suprathermal particles, which may reduce the efficiency of plasma heating by the alpha particles and other heating schemes involving fast ions. This paper presents calculations of guiding-center code alpha particle orbit loss from deuterium-tritium (DT) simulations of TFTR deuterium-only experiments. They are compared to results of measurements made in DT reversed shear plasmas of both the confined alpha particle distribution and the alpha particles lost from the plasma. Large fast particle losses have also been found in reversed shear ITER simulations (up to 20%) and from measurements of triton burnup in reversed shear experiments on JT-60U (12%).
Download or read book Chemical Abstracts written by and published by . This book was released on with total page 2664 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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