Morphologies Of Tungsten Nanotendrils Grown Under Helium Exposure
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Morphologies Of Tungsten Nanotendrils Grown Under Helium Exposure
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Author :
language : en
Publisher:
Release Date : 2017
Morphologies Of Tungsten Nanotendrils Grown Under Helium Exposure written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017 with categories.
Nanotendril "fuzz" will grow under He bombardment under tokamak-relevant conditions on tungsten plasma-facing materials in a magnetic fusion energy device. We have grown tungsten nanotendrils at low (50 eV) and high (12 keV) He bombardment energy, in the range 900-1000 °C, and characterized them using electron microscopy. Low energy tendrils are finer (~22 nm diameter) than high-energy tendrils (~176 nm diameter), and low-energy tendrils have a smoother surface than high-energy tendrils. Cavities were omnipresent and typically ~5-10 nm in size. Oxygen was present at tendril surfaces, but tendrils were all BCC tungsten metal. Electron diffraction measured tendril growth axes and grain boundary angle/axis pairs; no preferential growth axes or angle/axis pairs were observed, and low-energy fuzz grain boundaries tended to be high angle; high energy tendril grain boundaries were not observed. We speculate that the strong tendency to high-angle grain boundaries in the low-energy tendrils implies that as the tendrils twist or bend, strain must accumulate until nucleation of a grain boundary is favorable compared to further lattice rotation. Finally, the high-energy tendrils consisted of very large (>100 nm) grains compared to the tendril size, so the nature of the high energy irradiation must enable faster growth with less lattice rotation.
Characterization Of The Dynamic Formation Of Nano Tendril Surface Morphology On Tungsten While Exposed To Helium Plasma
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Author : Kevin Benjamin Woller
language : en
Publisher:
Release Date : 2017
Characterization Of The Dynamic Formation Of Nano Tendril Surface Morphology On Tungsten While Exposed To Helium Plasma written by Kevin Benjamin Woller and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017 with categories.
Tungsten undergoes surface morphology changes on the nanometer scale when subjected to low energy helium ion bombardment. This is due in part to the ion bombardment causing tungsten atoms to move on the surface, but also because of helium implantation and bubble development in the near surface at a depth 30 nm. At high enough surface temperatures, T/TM /~ 0.2, where TM is the melting temperature, nanoscale tendrils form on the surface and grow longer with additional bombardment by helium, but will decompose at the same temperature without helium bombardment. A tungsten surface that develops a densely packed layer of nano-tendrils over macroscopic areas greater than the grain size is referred to as tungsten fuzz, and is under intense study in fusion energy research, both for better understanding of how tungsten fuzz forms and of how tungsten fuzz affects the performance of plasma-facing components. The necessity of helium irradiation of the surface to induce nano-tendril growth motivates investigation into the dynamic process of helium implantation and accumulation in the surface. In this thesis, in situ elastic recoil detection is developed and used to measure the dynamic concentration of helium within a tungsten surface during the active growth of tungsten fuzz. During the development of in situ elastic recoil detection analysis, a variant of tungsten nano-tendril growth was discovered featuring drastically isolated bundles of nano-tendrils that grow at a higher rate than tungsten fuzz. The variation in nano-tendril morphology is correlated with incident helium ion energy modulation. The dependence on ion energy modulation and isolated nature of the nano-tendril bundles reveals clearly that nano-tendril growth is sensitive to surface kinetic effects. In this thesis, the structure and parameter space of the newly discovered nano-tendril bundle growth is analyzed with a suite of electron-based surface science techniques.
Plasma Nanoengineering And Nanofabrication
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Author : Krasimir Vasilev
language : en
Publisher: MDPI
Release Date : 2018-07-04
Plasma Nanoengineering And Nanofabrication written by Krasimir Vasilev and has been published by MDPI this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018-07-04 with Electronic book categories.
This book is a printed edition of the Special Issue "Plasma Nanoengineering and Nanofabrication" that was published in Nanomaterials
Characterization Of Helium Bubble Growth In Tungsten Exposed To Low Flux Plasmas
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Author :
language : en
Publisher:
Release Date : 2014
Characterization Of Helium Bubble Growth In Tungsten Exposed To Low Flux Plasmas written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with categories.
Morphology Changes Due To Energetic Helium Ion Irradiation Of Tungsten Surfaces At High Temperatures
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Author : Karla Brittany Hall
language : en
Publisher:
Release Date : 2019
Morphology Changes Due To Energetic Helium Ion Irradiation Of Tungsten Surfaces At High Temperatures written by Karla Brittany Hall and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019 with categories.
The Materials Irradiation Experiment (MITE-E) at the University of Wisconsin-Madison in the Inertial Electrostatic Confinement Laboratory was used to simulate helium ion (He+) irradiation of tungsten at fusion reactor relevant ion fluences and temperatures. Single and polycrystalline tungsten (SCW and PCW) samples were irradiated with 30-55 keV He+ at normal incidence with fluences of 3x1017 to 1019 He+/cm2 at temperatures from 500-900 oC. Post-irradiation analysis of the samples irradiated in the MITE-E device revealed several unique surface morphologies when the ion energy, temperature, and fluence were varied. Surface erosion due to energetic He+ irradiation was determined by mass loss measurements of samples pre- and post-irradiation. Past studies in the MITE-E revealed a surface orientation near {001} on PCW had considerably less erosion from He+ irradiation than surrounding grains Morphology development and mass loss measurements on [110] and [100] SCW revealed that the [100] crystal orientation lead to decreased surface erosion below 10^18 He+/cm2. Simulating what a fusion reactor component would likely experience, a sequentially increasing and decreasing multi-energy He+ irradiation on PCW was explored. Samples irradiated with increasing and decreasing multi-energy (35, 45, and 55 keV) He+ showed more surface damage than samples irradiated with mono-energetic (30 keV) He+. However, the multi-energy ion irradiated samples had less mass loss than the mono-energetic ion irradiated samples under similar parameters. Varying the temperature of samples under mono-energetic and multi-energy He+ irradiation at the same fluence caused an increase in mass loss as the temperature was decreased. The amount of mass loss and morphologies that developed on all samples point to He+ as a contributing mechanism in the undesired creation of W dust in a fusion reactor.
Physics Of Plasma Wall Interactions In Controlled Fusion
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Author : D. E. Post
language : en
Publisher: Springer Science & Business Media
Release Date : 2013-11-21
Physics Of Plasma Wall Interactions In Controlled Fusion written by D. E. Post and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013-11-21 with Science categories.
Controlled thermonuclear fusion is one of the possible candidates for long term energy sources which will be indispensable for our highly technological society. However, the physics and technology of controlled fusion are extremely complex and still require a great deal of research and development before fusion can be a practical energy source. For producing energy via controlled fusion a deuterium-tritium gas has to be heated to temperatures of a few 100 Million °c corres ponding to about 10 keV. For net energy gain, this hot plasma has to be confined at a certain density for a certain time One pro mising scheme to confine such a plasma is the use of i~tense mag netic fields. However, the plasma diffuses out of the confining magnetic surfaces and impinges on the surrounding vessel walls which isolate the plasma from the surrounding air. Because of this plasma wall interaction, particles from the plasma are lost to the walls by implantation and are partially reemitted into the plasma. In addition, wall atoms are released and can enter the plasma. These wall atoms or impurities can deteriorate the plasma performance due to enhanced energy losses through radiation and an increase of the required magnetic pressure or a dilution of the fuel in the plasma. Finally, the impact of the plasma and energy on the wall can modify and deteriorate the thermal and mechanical pro perties of the vessel walls.
Srim The Stopping And Range Of Ions In Matter
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Author : James F. Ziegler
language : en
Publisher: Lulu.com
Release Date : 2008
Srim The Stopping And Range Of Ions In Matter written by James F. Ziegler and has been published by Lulu.com this book supported file pdf, txt, epub, kindle and other format this book has been release on 2008 with Ion bombardment categories.
"This is a textbook the gives the background of the stopping and range of ions in matter (www.SRIM.org). It is written to be the prime resource for those who use SRIM in scientific work."--Lulu.com.
Cathodic Arcs
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Author : André Anders
language : en
Publisher: Springer Science & Business Media
Release Date : 2009-07-30
Cathodic Arcs written by André Anders and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009-07-30 with Science categories.
Cathodic arcs are among the longest studied yet least understood objects in science. Plasma-generating, tiny spots appear on the cathode; they are highly dynamic and hard to control. With an approach emphasizing the fractal character of cathode spots, strongly fluctuating plasma properties are described such as the presence of multiply charged ions that move with supersonic velocity. Richly illustrated, the book also deals with practical issues, such as arc source construction, macroparticle removal, and the synthesis of dense, well adherent coatings. The book spans a bridge from plasma physics to coatings technology based on energetic condensation, appealing to scientists, practitioners and graduate students alike.
Ion Solid Interactions
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Author : Michael Nastasi
language : en
Publisher: Cambridge University Press
Release Date : 1996-03-29
Ion Solid Interactions written by Michael Nastasi and has been published by Cambridge University Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 1996-03-29 with Science categories.
Comprehensive guide to an important materials science technique for students and researchers.
On The Edge Of Magnetic Fusion Devices
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Author : Sergei Krasheninnikov
language : en
Publisher: Springer
Release Date : 2021-09-09
On The Edge Of Magnetic Fusion Devices written by Sergei Krasheninnikov and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2021-09-09 with Science categories.
This book reviews the current state of understanding concerning edge plasma, which bridges hot fusion plasma, with a temperature of roughly one million degrees Kelvin with plasma-facing materials, which have melting points of only a few thousand degrees Kelvin. In a fact, edge plasma is one of the keys to solution for harnessing fusion energy in magnetic fusion devices. The physics governing the processes at work in the edge plasma involves classical and anomalous transport of multispecies plasma, neutral gas dynamics, atomic physics effects, radiation transport, plasma-material interactions, and even the transport of plasma species within the plasma-facing materials. The book starts with simple physical models, then moves on to rigorous theoretical considerations and state-of-the-art simulation tools that are capable of capturing the most important features of the edge plasma phenomena. The authors compare the conclusions arising from the theoretical and computational analysis with the available experimental data. They also discuss the remaining gaps in their models and make projections for phenomena related to edge plasma in magnetic fusion reactors.