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Disruption Mitigation By Massive Gas Injection In Jet
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Book Synopsis Disruption Mitigation by Massive Gas Injection in JET by : A. Alonso
Download or read book Disruption Mitigation by Massive Gas Injection in JET written by A. Alonso and published by . This book was released on 2011* with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Disruption mitigation is mandatory for ITER in order to reduce forces and to mitigate heat loads during the Thermal Quench (TQ) and from runaway electrons. A fast Disruption Mitigation Valve (DMV) has been installed at JET to study mitigation by Massive Gas Injection (MGI). Different gas species and amounts have been investigated with respect to timescales and mitigation efficiency. We discuss the mitigation of halo currents as well as sideways forces during vertical displacement events, the mitigation of heat loads by increased energy dissipation through radiation, the heat loads which could arise by asymmetric radiation and the suppression of runaway electrons."--Abstract.
Book Synopsis Disruption Mitigation Using High Pressure Gas Jets by :
Download or read book Disruption Mitigation Using High Pressure Gas Jets written by and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The goal of this research is to establish credible disruption mitigation scenarios based on the technique of massive gas injection. Disruption mitigation seeks to minimize or eliminate damage to internal components that can occur due to the rapid dissipation of thermal and magnetic energy during a tokamak disruption. In particular, the focus of present research is extrapolating mitigation techniques to burning plasma experiments such as ITER, where disruption-caused damage poses a serious threat to the lifetime of internal vessel components. A majority of effort has focused on national and international collaborative research with large tokamaks: DIII-D, Alcator C-Mod, JET, and ASDEX Upgrade. The research was oriented towards empirical trials of gas-jet mitigation on several tokamaks, with the goal of developing and applying cohesive models to the data across devices. Disruption mitigation using gas jet injection has proven to be a viable candidate for avoiding or minimizing damage to internal components in burning plasma experiments like ITER. The physics understanding is progress towards a technological design for the required gas injection system in ITER.
Book Synopsis DISRUPTION MITIGATION USING HIGH-PRESSURE NOBLE GAS INJECTION ON DIII-D. by :
Download or read book DISRUPTION MITIGATION USING HIGH-PRESSURE NOBLE GAS INJECTION ON DIII-D. written by and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: High-pressure gas jet injection of neon and argon is used to mitigate the deleterious effects from tokamak disruptions. Thermal loading of the divertor surfaces, vessel stress from poloidal halo currents and the buildup and loss of relativistic electrons to the wall are all greatly reduced or eliminated. The gas jet penetrates through to the central plasma as a neutral species at its sonic velocity[approx] 300-500 m/s. The injected impurity species radiate> 95% of the plasma stored energy, accompanied by a 500-fold increase the total electron inventory in the plasma volume, thus decreasing localized heating at the divertor targets. The poloidal halo currents at the wall are reduced because of the rapid cooling and the slow movement of the plasma toward the wall during the current quench. When a sufficient quantity of gas is injected, the extremely large total (free+ bound) electron density inhibits runaway electrons in the current quench, as predicted. A physical model of radiative cooling has been developed and is validated against DIII-D experiments. The model shows that gas jet mitigation, including runaway suppression, extrapolates favorably to burning plasmas where disruption damage would be more severe. The use of real-time detection of the onset of a disruption to trigger massive gas injection and to mitigate the ensuing damage is demonstrated.
Book Synopsis DIII-D Studies of Massive Gas Injection Fast Shutdowns for Disruption Mitigation by : D. Gray
Download or read book DIII-D Studies of Massive Gas Injection Fast Shutdowns for Disruption Mitigation written by D. Gray and published by . This book was released on 2006 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: Injection of massive quantities of gas is a promising technique for fast shutdown of ITER for the purpose of avoiding divertor and first wall damage from disruptions. Previous experiments using massive gas injection (MGI) to terminate discharges in the DIII-D tokamak have demonstrated rapid shutdown with reduced wall heating and halo currents (relative to natural disruptions) and with very small runaway electron (RE) generation [1]. Figure 1 shows time traces which give an overview of shutdown time scales. Typically, of order 5 x 10{sup 22} Ar neutrals are fired over a pulse of 25 ms duration into stationary (non-disrupting) discharges. The observed results are consistent with the following scenario: within several ms of the jet trigger, sufficient Ar neutrals are delivered to the plasma to cause the edge temperature to collapse, initiating the inward propagation of a cold front. The exit flow of the jet [Fig. 1(a)] has a {approx} 9 ms rise time; so the quantity of neutrals which initiates the edge collapse is small (10{sup 20}). When the cold front reaches q {approx} 2 surface, global magnetohydrodynamic (MHD) modes are destabilized [2], mixing hot core plasma with edge impurities. Here, q is the safety factor. Most (90%) of the plasma thermal energy is lost via impurity radiation during this thermal quench (TQ) phase. Conducted heat loads to the wall are low because of the cold edge temperature. After the TQ, the plasma is very cold (of order several eV), so conducted wall (halo) currents are low, even if the current channel contacts the wall. The plasma current profile broadens and begins decaying resistively. The decaying current generates a toroidal electric field which can accelerate REs; however, RE beam formation appears to be limited in MGI shutdowns. Presently, it is thought that the conducted heat flux and halo current mitigation qualities of the MGI shutdown technique will scale well to a reactor-sized tokamak. However, because of the larger RE gain from avalanching and the presence of a RE seed population due to Compton-scattered fast electrons, it is possible that a RE beam can be formed well into the CQ, after the flux surfaces initially destroyed by the TQ MHD have had time to heal. Crucial MGI issues to be studied in present devices are therefore the formation, amplification, and transport of RE and the transport of impurities into the core plasma (important because the presence of impurities can, via collisional drag, help suppress RE amplification). In the study of impurity transport, both neutral delivery (directly driven into the core by the jet pressure) and ion delivery (mixed into the core by MHD) are of interest, as both contribute to RE drag. Here, three new results relevant to RE suppression from MGI are presented: (1) evidence is presented that neutral jet propagation is stopped by toroidal magnetic field pressure, (2) MGI appears to cause the CQ to begin before sufficient impurities have been injected for complete collisional suppression of RE, and (3) flux surface destruction over the region q {le} 2 occurs during the TQ. The first result suggests that neutrals cannot be delivered to the core of large tokamak discharges by MGI, even during the CQ. The second result indicates that (at least for argon MGI in DIII-D), insufficient impurities (either neutral or ion) are delivered for collisional suppression of RE at the start of the CQ. The last result suggests that the destruction of good field lines resulting from MGI is quite extensive and should be sufficient to prevent RE formation, at least at the start of the CQ.
Book Synopsis DIII-D Studies of Massive Gas Injection Fast Shutdowns for Disruption Mitigation by :
Download or read book DIII-D Studies of Massive Gas Injection Fast Shutdowns for Disruption Mitigation written by and published by . This book was released on 2006 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: Injection of massive quantities of gas is a promising technique for fast shutdown of ITER for the purpose of avoiding divertor and first wall damage from disruptions. Previous experiments using massive gas injection (MGI) to terminate discharges in the DIII-D tokamak have demonstrated rapid shutdown with reduced wall heating and halo currents (relative to natural disruptions) and with very small runaway electron (RE) generation [1]. Figure 1 shows time traces which give an overview of shutdown time scales. Typically, of order 5 x 1022 Ar neutrals are fired over a pulse of 25 ms duration into stationary (non-disrupting) discharges. The observed results are consistent with the following scenario: within several ms of the jet trigger, sufficient Ar neutrals are delivered to the plasma to cause the edge temperature to collapse, initiating the inward propagation of a cold front. The exit flow of the jet [Fig. 1(a)] has a (almost equal to) 9 ms rise time; so the quantity of neutrals which initiates the edge collapse is small (102°). When the cold front reaches q (almost equal to) 2 surface, global magnetohydrodynamic (MHD) modes are destabilized [2], mixing hot core plasma with edge impurities. Here, q is the safety factor. Most (90%) of the plasma thermal energy is lost via impurity radiation during this thermal quench (TQ) phase. Conducted heat loads to the wall are low because of the cold edge temperature. After the TQ, the plasma is very cold (of order several eV), so conducted wall (halo) currents are low, even if the current channel contacts the wall. The plasma current profile broadens and begins decaying resistively. The decaying current generates a toroidal electric field which can accelerate REs; however, RE beam formation appears to be limited in MGI shutdowns. Presently, it is thought that the conducted heat flux and halo current mitigation qualities of the MGI shutdown technique will scale well to a reactor-sized tokamak. However, because of the larger RE gain from avalanching and the presence of a RE seed population due to Compton-scattered fast electrons, it is possible that a RE beam can be formed well into the CQ, after the flux surfaces initially destroyed by the TQ MHD have had time to heal. Crucial MGI issues to be studied in present devices are therefore the formation, amplification, and transport of RE and the transport of impurities into the core plasma (important because the presence of impurities can, via collisional drag, help suppress RE amplification). In the study of impurity transport, both neutral delivery (directly driven into the core by the jet pressure) and ion delivery (mixed into the core by MHD) are of interest, as both contribute to RE drag.
Download or read book Xiu xiang ju xian zhen gu ci written by and published by . This book was released on with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Modeling of Massive Gas Injection Triggered Disruptions in Tokamak Plasmas by : Alexandre Fil
Download or read book Modeling of Massive Gas Injection Triggered Disruptions in Tokamak Plasmas written by Alexandre Fil and published by . This book was released on 2015 with total page 133 pages. Available in PDF, EPUB and Kindle. Book excerpt: Plasma disruptions are events occuring in tokamaks which result in the total loss of the plasma confinement and the end of the discharge. These disruptions are rapid and violent events and they can damage the tokamak walls and its structure if they are not controlled. A Disruption Mitigation System (DMS) is thus mandatory in ITER in order to reduce electromagnetic forces, mitigate heat loads and avoid Runaway Electrons (RE) generated by plasma disruptions. These combined objectives make the design of the DMS a complex and challenging task, for which substantial input from both experiments and modeling is needed. We present here modeling results on disruption mitigation by Massive Gas Injection (MGI), which is one of the main methods considered for the DMS of ITER. First, a model which stems from first principles is given for the tranport of neutrals in a plasma and applied to the study of the interaction of the MGI with the plasma. Main mechanisms responsible for the penetration of the neutral gas are described and studied. Charge-exchange processes between the neutrals and the ions of the plasma is found to play a major role. Then, the 3D non linear MHD code JOREK is applied to the study of MGI-triggered disruptions with a particular focus on the thermal quench phase and the MHD events which are responsible for it. The simulation results are compared to experiments done on the JET tokamak.
Book Synopsis Three-dimensional Non-linear MHD Modeling of Massive Gas Injection Triggered Disruptions in JET by : A. Fil
Download or read book Three-dimensional Non-linear MHD Modeling of Massive Gas Injection Triggered Disruptions in JET written by A. Fil and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Measurements of Impurity and Heat Dynamics During Noble Gas Jet-Initiated Fast Plasma Shutdown for Disruption Mitigation in DIII-D. by : D. S. Gray
Download or read book Measurements of Impurity and Heat Dynamics During Noble Gas Jet-Initiated Fast Plasma Shutdown for Disruption Mitigation in DIII-D. written by D. S. Gray and published by . This book was released on 2004 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: Impurity deposition and mixing during gas jet-initiated plasma shutdown is studied using a rapid ({approx}2 ms), massive ({approx}10{sup 22} particles) injection of neon or argon into stationary DIII-D H-mode discharges. Fast-gated camera images indicate that the bulk of the jet neutrals do not penetrate far into the plasma pedestal. Nevertheless, high ({approx}90%) thermal quench radiated power fractions are achieved; this appears to be facilitated through a combination of fast ion mixing and fast heat transport, both driven by large-scale MHD activity. Also, runaway electron suppression is achieved for sufficiently high gas jet pressures. These experiments suggest that massive gas injection could be viable for disruption mitigation in future tokamaks even if core penetration of jet neutrals is not achieved.
Book Synopsis Conformal and Probabilistic Prediction with Applications by : Alexander Gammerman
Download or read book Conformal and Probabilistic Prediction with Applications written by Alexander Gammerman and published by Springer. This book was released on 2016-04-16 with total page 235 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book constitutes the refereed proceedings of the 5th International Symposium on Conformal and Probabilistic Prediction with Applications, COPA 2016, held in Madrid, Spain, in April 2016. The 14 revised full papers presented together with 1 invited paper were carefully reviewed and selected from 23 submissions and cover topics on theory of conformal prediction; applications of conformal prediction; and machine learning.
Book Synopsis Plasma-Material Interactions in a Controlled Fusion Reactor by : Tetsuo Tanabe
Download or read book Plasma-Material Interactions in a Controlled Fusion Reactor written by Tetsuo Tanabe and published by Springer Nature. This book was released on 2021-03-08 with total page 209 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a primer on the interplay between plasma and materials in a fusion reactor, so-called plasma–materials interactions (PMIs), highlighting materials and their influence on plasma through PMI. It aims to demonstrate that a plasma-facing surface (PFS) responds actively to fusion plasma and that the clarifying nature of PFS is indispensable to understanding the influence of PFS on plasma. It describes the modern insight into PMI, namely, relevant feedback to plasma performance from plasma-facing material (PFM) on changes in a material surface by plasma power load by radiation and particles, contrary to a conventional view that unilateral influence from plasma on PFM is dominant in PMI. There are many books and reviews on PMI in the context of plasma physics, that is, how plasma or plasma confinement works in PMI. By contrast, this book features a materials aspect in PMI focusing on changes caused by heat and particle load from plasma: how PFMs are changed by plasma exposure and then, accordingly, how the changed PFM interacts with plasma.
Book Synopsis Self-consistent Modeling of Plasma Response to Impurity Spreading from Intense Localized Source by : Mikhail Koltunov
Download or read book Self-consistent Modeling of Plasma Response to Impurity Spreading from Intense Localized Source written by Mikhail Koltunov and published by Forschungszentrum Jülich. This book was released on 2012 with total page 131 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :National Academies of Sciences, Engineering, and Medicine Publisher :National Academies Press ISBN 13 :0309487463 Total Pages :341 pages Book Rating :4.3/5 (94 download)
Book Synopsis Final Report of the Committee on a Strategic Plan for U.S. Burning Plasma Research by : National Academies of Sciences, Engineering, and Medicine
Download or read book Final Report of the Committee on a Strategic Plan for U.S. Burning Plasma Research written by National Academies of Sciences, Engineering, and Medicine and published by National Academies Press. This book was released on 2019-05-31 with total page 341 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fusion offers the prospect of virtually unlimited energy. The United States and many nations around the world have made enormous progress toward achieving fusion energy. With ITER scheduled to go online within a decade and demonstrate controlled fusion ten years later, now is the right time for the United States to develop plans to benefit from its investment in burning plasma research and take steps to develop fusion electricity for the nation's future energy needs. At the request of the Department of Energy, the National Academies of Sciences, Engineering, and Medicine organized a committee to develop a strategic plan for U.S. fusion research. The final report's two main recommendations are: (1) The United States should remain an ITER partner as the most cost-effective way to gain experience with a burning plasma at the scale of a power plant. (2) The United States should start a national program of accompanying research and technology leading to the construction of a compact pilot plant that produces electricity from fusion at the lowest possible capital cost.
Book Synopsis Mitigation of Upward and Downward Vertical Displacement Event Heat Loads with Upper Or Lower Massive Gas Injection in DIII-D. by :
Download or read book Mitigation of Upward and Downward Vertical Displacement Event Heat Loads with Upper Or Lower Massive Gas Injection in DIII-D. written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Intentionally triggered upward and downward vertical displacement events (VDEs) leading to disruptions were pre-emptively mitigated with neon massive gas injection (MGI) coming from either above or below the plasma. Global indicators of disruption mitigation effectiveness (conducted heat loads, radiated power, and vessel motion) do not show a clear improvement when mitigating with the gas jet located closer to the VDE impact area. A clear trend of improved mitigation is observed for earlier MGI timing relative to the VDE impact time. The plasma current channel is seen to lock to a preferential phase during the VDE thermal quench, but this phase is not clearly matched by preliminary attempts to fit to the conducted heat load phase. Finally, clear indications of plasma infra-red emission are observed both before and during the disruptions; this infrared emission can affect calculation of disruption heat loads.
Download or read book Heat Transfer written by Salim Newaz Kazi and published by BoD – Books on Demand. This book was released on 2015-07-29 with total page 408 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the wake of energy crisis due to rapid growth of industries, the efficient heat transfer could play a vital role in energy saving. Industries, household equipment, transportation, offices, etc., all are dependent on heat exchanging equipment. Considering this, the book has incorporated different chapters on heat transfer phenomena, analytical and experimental heat transfer investigations, heat transfer enhancement and applications.
Book Synopsis Nonlinear Magnetohydrodynamics by : D. Biskamp
Download or read book Nonlinear Magnetohydrodynamics written by D. Biskamp and published by Cambridge University Press. This book was released on 1997-07-17 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt: A self-contained introduction to magnetohydrodynamics with emphasis on nonlinear processes.
Book Synopsis Issues in Water and Power Engineering: 2011 Edition by :
Download or read book Issues in Water and Power Engineering: 2011 Edition written by and published by ScholarlyEditions. This book was released on 2012-01-09 with total page 1005 pages. Available in PDF, EPUB and Kindle. Book excerpt: Issues in Water and Power Engineering / 2011 Edition is a ScholarlyEditions™ eBook that delivers timely, authoritative, and comprehensive information about Water and Power Engineering. The editors have built Issues in Water and Power Engineering: 2011 Edition on the vast information databases of ScholarlyNews.™ You can expect the information about Water and Power Engineering in this eBook to be deeper than what you can access anywhere else, as well as consistently reliable, authoritative, informed, and relevant. The content of Issues in Water and Power Engineering: 2011 Edition has been produced by the world’s leading scientists, engineers, analysts, research institutions, and companies. All of the content is from peer-reviewed sources, and all of it is written, assembled, and edited by the editors at ScholarlyEditions™ and available exclusively from us. You now have a source you can cite with authority, confidence, and credibility. More information is available at http://www.ScholarlyEditions.com/.
