Sawtooth Mixing of Alpha Particles in TFTR D-T Plasmas PDF Download
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Author: Mikhail Petrovich Petrov
Publisher:
ISBN:
Category : Alpha rays
Languages : en
Pages : 10
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Author: Mikhail Petrovich Petrov
Publisher:
ISBN:
Category : Alpha rays
Languages : en
Pages : 10
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Book Description
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 10
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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 (
Author: B. C. Stratton
Publisher:
ISBN:
Category : Alpha rays
Languages : en
Pages : 7
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Author: B. C. Stratton
Publisher:
ISBN:
Category : Alpha rays
Languages : en
Pages : 7
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Author: R. V. Budny
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ISBN:
Category : Alpha rays
Languages : en
Pages : 36
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Author:
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ISBN:
Category : Controlled fusion
Languages : en
Pages : 962
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Author:
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ISBN:
Category : Power resources
Languages : en
Pages : 1468
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![Simulation of [alpha]-particle Redistribution Due to Sawteeth on TFTR. PDF](https://books.google.com/books/content/images/frontcover/d_OSAQAACAAJ?fife=w80-h100)
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Category :
Languages : en
Pages : 26
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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.
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Category :
Languages : en
Pages :
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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.
Author:
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Category : Electronic journals
Languages : en
Pages : 436
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