Possible non-thermal effects in stellar nuclear reactions

Gilles Beaudet; G. Shaviv

doi:10.1007/bf00644161

The Radiochemistry of Organoiron Compounds. III. Fe(CO)5–Cyclopentadiene Solutions

Canadian Journal of Chemistry ◽

10.1139/v73-033 ◽

1973 ◽

Vol 51 (2) ◽

pp. 215-218 ◽

Cited By ~ 2

Author(s):

W. Kanellakopulos-Drossopulos ◽

D. R. Wiles

Keyword(s):

Concentration Dependence ◽

Solid Solutions ◽

Thermal Effects ◽

Nuclear Reactions

Nucleogenesis of 59Fe gives iron atoms which react with monomeric cyclopentadiene to produce 59FeCp2, either in liquid or solid solutions, but do not react appreciably with dimeric cyclopentadiene. This is taken as showing that local thermal effects of the nuclear reactions are ineffective in causing the dissociation (C5H6)2 → 2C5H6. The concentration dependence of the yield of 59FeCp2 indicates that the 59Fe atom reacts primarily at its point of genesis rather than after diffusion.

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Activities in Divertor Reflector and Linear Plates Using WCLL and HCPB Breeding Blanket Concepts

Energies ◽

10.3390/en14248305 ◽

2021 ◽

Vol 14 (24) ◽

pp. 8305

Author(s):

Simona Breidokaite ◽

Gediminas Stankunas

Keyword(s):

Cross Sections ◽

Thermal Effects ◽

Nuclear Reactions ◽

Nuclear Data ◽

Alpha Particles ◽

Vacuum Vessel ◽

Plasma Facing Components ◽

Nuclear Data Library ◽

Safe Performance ◽

Data Library

In fusion devices, such as European Demonstration Fusion Power Reactor (EU DEMO), primary neutrons can cause material activation due to the interaction between the source particles and the targeting material. Subsequently, the reactor’s inner components become activated. For safety and safe performance purposes, it is necessary to evaluate neutron-induced activities. Activities results from divertor reflector and liner plates are presented in this work. The purpose of liner shielding plates is to protect the vacuum vessel and magnet coils from neutrons. As for reflector plates, the function is to shield the cooling components under plasma-facing components from alpha particles, thermal effects, and impurities. Plates are made of Eurofer with a 3 mm layer of tungsten, while the water is used for cooling purposes. The calculations were performed using two EU DEMO MCNP (Monte Carlo N-Particles) models with different breeding blanket configurations: helium-cooled pebble bed (HCPB) and water-cooled lithium lead (WCLL). The TENDL–2017 nuclear data library has been used for activation reactions cross-sections and nuclear reactions. Activation calculations were performed using the FISPACT-II code at the end of irradiation for cooling times of 0 s–1000 years. Radionuclide analysis of divertor liner and reflector plates is also presented in this paper. The main radionuclides, with at least 1% contribution to the total value of activation characteristics, were identified for the previously mentioned cooling times.

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Nuclear Processes Related to the Ap Stars and the Heaviest Chemical Elements

International Astronomical Union Colloquium ◽

10.1017/s0252921100080520 ◽

1976 ◽

Vol 32 ◽

pp. 169-182

Author(s):

B. Kuchowicz

Keyword(s):

Nuclear Physics ◽

Nuclear Reactions ◽

Chemical Elements ◽

Fission Products ◽

Abundance Pattern ◽

Isotopic Shifts ◽

Processed Material ◽

R Process ◽

Ap Stars ◽

Nuclear Processes

SummaryIsotopic shifts in the lines of the heavy elements in Ap stars, and the characteristic abundance pattern of these elements point to the fact that we are observing mainly the products of rapid neutron capture. The peculiar A stars may be treated as the show windows for the products of a recent r-process in their neighbourhood. This process can be located either in Supernovae exploding in a binary system in which the present Ap stars were secondaries, or in Supernovae exploding in young clusters. Secondary processes, e.g. spontaneous fission or nuclear reactions with highly abundant fission products, may occur further with the r-processed material in the surface of the Ap stars. The role of these stars to the theory of nucleosynthesis and to nuclear physics is emphasized.

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Thermal Considerations in Lens Regulator Systems

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100068783 ◽

1970 ◽

Vol 28 ◽

pp. 358-359

Author(s):

K.C. Newton

Keyword(s):

Electron Microscope ◽

Thermal Effects ◽

Environmental Control ◽

Reference Networks ◽

Better Than

Thermal effects in lens regulator systems have become a major problem with the extension of electron microscope resolution capabilities below 5 Angstrom units. Larger columns with immersion lenses and increased accelerating potentials have made solutions more difficult by increasing the power being handled. Environmental control, component choice, and wiring design provide answers, however. Figure 1 indicates with broken lines where thermal problems develop in regulator systemsExtensive environmental control is required in the sampling and reference networks. In each case, stability better than I ppm/min. is required. Components with thermal coefficients satisfactory for these applications without environmental control are either not available or priced prohibitively.

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Nuclear Reactions in Deuterium Titanium

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100134260 ◽

1990 ◽

Vol 48 (2) ◽

pp. 134-135

Author(s):

D.M. Vanderwalker

Keyword(s):

Nuclear Reactions ◽

Ion Beam ◽

Exothermic Reaction ◽

Pure Titanium ◽

Fundamental Interest ◽

Transmission Electron ◽

Iodide Titanium ◽

A Cell ◽

After Hours ◽

Quantity Of Heat

There is a fundamental interest in electrochemical fusion of deuterium in palladium and titanium since its supposed discovery by Fleischmann and Pons. Their calorimetric experiments reveal that a large quantity of heat is released by Pd after hours in a cell, suggesting fusion occurs. They cannot explain fusion by force arguments, nor can it be an exothermic reaction on the formation of deuterides because a smaller quantity of heat is released. This study examines reactions of deuterium in titanium.Both iodide titanium and 99% pure titanium samples were encapsulated in vacuum tubes, annealed for 2h at 800 °C. The Ti foils were charged with deuterium in a D2SO4 D2O solution at a potential of .45V with respect to a calomel reference junction. Samples were ion beam thinned for transmission electron microscopy. The TEM was performed on the JEOL 200CX.The structure of D charged titanium is α-Ti with hexagonal and fee deuterides.

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Direct measurement of electron-diffraction-pattern intensities using an energy loss spectrometer

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100155311 ◽

1989 ◽

Vol 47 ◽

pp. 668-669

Author(s):

A. G. Jackson ◽

M. Rowe

Keyword(s):

Thermal Effects ◽

Dynamic Range ◽

Scattering Amplitude ◽

Dynamical Theory ◽

Site Symmetry ◽

Proof Of Concept ◽

Parallel Acquisition ◽

Kinematic Approximation ◽

Speed Up ◽

Structure Calculations

Diffraction intensities from intermetallic compounds are, in the kinematic approximation, proportional to the scattering amplitude from the element doing the scattering. More detailed calculations have shown that site symmetry and occupation by various atom species also affects the intensity in a diffracted beam. [1] Hence, by measuring the intensities of beams, or their ratios, the occupancy can be estimated. Measurement of the intensity values also allows structure calculations to be made to determine the spatial distribution of the potentials doing the scattering. Thermal effects are also present as a background contribution. Inelastic effects such as loss or absorption/excitation complicate the intensity behavior, and dynamical theory is required to estimate the intensity value.The dynamic range of currents in diffracted beams can be 104or 105:1. Hence, detection of such information requires a means for collecting the intensity over a signal-to-noise range beyond that obtainable with a single film plate, which has a S/N of about 103:1. Although such a collection system is not available currently, a simple system consisting of instrumentation on an existing STEM can be used as a proof of concept which has a S/N of about 255:1, limited by the 8 bit pixel attributes used in the electronics. Use of 24 bit pixel attributes would easily allowthe desired noise range to be attained in the processing instrumentation. The S/N of the scintillator used by the photoelectron sensor is about 106 to 1, well beyond the S/N goal. The trade-off that must be made is the time for acquiring the signal, since the pattern can be obtained in seconds using film plates, compared to 10 to 20 minutes for a pattern to be acquired using the digital scan. Parallel acquisition would, of course, speed up this process immensely.

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The evolution of the microstructure of 600 Mev proton irradiated materials

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100178148 ◽

1990 ◽

Vol 48 (4) ◽

pp. 1002-1003

Author(s):

R. Gotthardt ◽

A. Horsewell ◽

F. Paschoud ◽

S. Proennecke ◽

M. Victoria

Keyword(s):

Nuclear Reactions ◽

Dislocation Loops ◽

Defect Clusters ◽

Weak Beam ◽

Stacking Fault Tetrahedra ◽

Small Defect ◽

Sufficient Intensity ◽

Reactor Materials ◽

Metallic Impurities ◽

Beam Technique

Fusion reactor materials will be damaged by an intense field of energetic neutrons. There is no neutron source of sufficient intensity at these energies available at present, so the material properties are being correlated with those obtained in irradiation with other irradiation sorces. Irradiation with 600 MeV protons produces both displacement damage and impurities due to nuclear reactions. Helium and hydrogen are produced as gaseous impurities. Other metallic impurities are also created . The main elements of the microstructure observed after irradiation in the PIREX facility, are described in the following paragraphs.A. Defect clusters at low irradiation doses: In specimens irradiated to very low doses (1021-1024 protons.m-2), so that there is no superimposition of contrast, small defect clusters have been observed by the weak beam technique. Detailed analysis of the visible contrast (>0.5 nm diameter) revealed the presence of stacking fault tetrahedra, dislocation loops and a certain number of unidentified clusters . Typical results in Cu and Au are shown in Fig. 1.

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