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Divertor Heat Loads In Rmp Elm Controlled H Mode Plasmas On Diii D
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Book Synopsis Divertor Heat Loads in RMP ELM Controlled H-mode Plasmas on DIII-D* by :
Download or read book Divertor Heat Loads in RMP ELM Controlled H-mode Plasmas on DIII-D* written by and published by . This book was released on 2008 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this paper the manipulation of power deposition on divertor targets at DIII-D by application of resonant magnetic perturbations (RMPs) is analyzed. It has been found that heat transport shows a different reaction to the applied RMP depending on the plasma pedestal collisionality. At pedestal electron collisionality above 0.5 the heat flux during the ELM suppressed phase is of the same order as the inter-ELM in the non-RMP phase. Below this collisionality value we observe a slight increase of the total power flux to the divertor. This can be caused by much more negative potential at the divertor surface due to hot electrons reaching the divertor surface from the pedestal area and/or so called pump out effect. In the second part we discuss modification of ELM behavior due to the RMP. It is shown, that the width of the deposition pattern in ELMy H-mode depends linearly on the ELM deposited energy, whereas in the RMP phase of the discharge those patterns seem to be controlled by the externally induced magnetic perturbation. D2 pellets injected into the plasma bulk during ELM-free RMP H-mode lead in some cases to a short term small transients, which have very similar properties to ELMs in the initial RMP-on phase.
Book Synopsis Overview of the Results on Divertor Heat Loads in RMP Controlled H-modeplasmas on DIII-D. by :
Download or read book Overview of the Results on Divertor Heat Loads in RMP Controlled H-modeplasmas on DIII-D. written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper demonstrates the manipulation of power deposition on divertor targets at DIII-D by the application of resonant magnetic perturbations (RMPs) for suppression of large type-I edge localized modes (ELMs) is analysed. We discuss the modification of the ELM characteristics by the RMP applied. It is shown that the width of the deposition pattern in ELMy H-mode depends linearly on the ELM deposited energy, whereas in the RMP phase of the discharge those patterns are controlled by the externally induced magnetic perturbation. It was also found that the manipulation of heat transport due to the application of small, edge RMP depends on the plasma pedestal electron collisionality. We then compare in this analysis RMP and no RMP phases with and without complete ELM suppression. At high, the heat flux during the ELM suppressed phase is of the same order as the inter-ELM and the no-RMP phase. However, below this collisionality value, a slight increase in the total power flux to the divertor is observed during the RMP phase. We surmised that this is most likely caused by a more negative potential at the divertor surface due to hot electrons reaching the divertor surface from the pedestal area along perturbed, open field lines.
Book Synopsis Divertor-plasma Studies on DIII-D. by :
Download or read book Divertor-plasma Studies on DIII-D. written by and published by . This book was released on 1990 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper presents an overview of recent results from divertor physics studies in DIII-D. Heat flux measurements at input power levels up to 20 MW show that steady divertor heat loads of up to 4 MW/m2 are obtained in H-mode discharges with ELMs. No carbon blooms are observed. The heat flux profile is highly peaked at the outside strike point in single-null discharges, and is up/down asymmetric in double-null discharges. Recent experiments with gas injection below the X-point have demonstrated a factor of two reduction in the peak divertor heat flux for H-mode plasmas at these power levels. These heat flux data, along with measurements of the n{sub e} and T{sub e} profiles at the divertor are being used to help interpret the first reported measurements of the erosion profile for a set of graphite divertor tiles exposed to several months of high power tokamak operation. We have now modified the divertor hardware in order to carry out experiments with divertor biasing, baffling, and pumping. 26 refs., 8 figs.
Book Synopsis Divertor Heat and Particle Control Experiments on the DIII-D Tokamak by :
Download or read book Divertor Heat and Particle Control Experiments on the DIII-D Tokamak written by and published by . This book was released on 1994 with total page 39 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this paper we present a summary of recent DIII-D divertor physics activity and plans for future divertor upgrades. During the past year, DIII-D experimental effort was focused on areas of active heat and particle control and divertor target erosion studies. Using the DIII-D Advanced Divertor system we have succeeded for the first time to control the plasma density and demonstrate helium exhaust in H-mode plasmas. Divertor heat flux control by means of D2 gas puffing and impurity injection were studied separately and in, both cases up to a factor of five reduction of the divertor peak heat flux was observed. Using the DiMES sample transfer system we have obtained erosion data on various material samples in well diagnosed plasmas and compared the results with predictions of numerical models.
Book Synopsis Regular and Chaotic Dynamics by : A.J. Lichtenberg
Download or read book Regular and Chaotic Dynamics written by A.J. Lichtenberg and published by Springer Science & Business Media. This book was released on 2013-03-14 with total page 708 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book treats nonlinear dynamics in both Hamiltonian and dissipative systems. The emphasis is on the mechanics for generating chaotic motion, methods of calculating the transitions from regular to chaotic motion, and the dynamical and statistical properties of the dynamics when it is chaotic. The new edition brings the subject matter in a rapidly expanding field up to date, and has greatly expanded the treatment of dissipative dynamics to include most important subjects.
Book Synopsis Simulations of Divertor Particle and Heat Loads in Ohmic and L-mode Plasmas in DIII-D, AUG, and JET Using UEDGE. by :
Download or read book Simulations of Divertor Particle and Heat Loads in Ohmic and L-mode Plasmas in DIII-D, AUG, and JET Using UEDGE. written by and published by . This book was released on 2010 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Systems Approaches to Nuclear Fusion Reactors by : Frederick B. Marcus
Download or read book Systems Approaches to Nuclear Fusion Reactors written by Frederick B. Marcus and published by Springer Nature. This book was released on 2023-01-01 with total page 484 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book offers an overall review, applying systems engineering and architecture approaches, of the design, optimization, operation and results of leading fusion experiments. These approaches provide a unified means of evaluating reactor design. Methodologies are developed for more coherent construction or evaluation of fusion devices, associated experiments and operating procedures. The main focus is on tokamaks, with almost all machines and their important results being integrated into a systems design space. Case studies focus on DIII-D, TCV, JET, WEST, the fusion reactor prototype ITER and the EU DEMO concept. Stellarator, Mirror and Laser inertial confinement experiments are similarly analysed, including reactor implications of breakeven at NIF. The book examines the engineering and physics design and optimization process for each machine, analysing their performance and major results achieved, thus establishing a basis for the improvement of future machines. The reader will gain a broad historical and up-to-date perspective of the status of nuclear fusion research from both an engineering and physics point of view. Explanations are given of the computational tools needed to design and operate successful experiments and reactor-relevant machines. This book is aimed at both graduate students and practitioners of nuclear fusion science and engineering, as well as those specializing in other fields demanding large and integrated experimental equipment. Systems engineers will obtain valuable insights into fusion applications. References are given to associated complex mathematical derivations, which are beyond the scope of this book. The general reader interested in nuclear fusion will find here an accessible summary of the current state of nuclear fusion.
Book Synopsis Divertor Research on the DIII-D Tokamak by :
Download or read book Divertor Research on the DIII-D Tokamak written by and published by . This book was released on 1994 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Integration of a Radiative Divertor for Heat Load Control Into JET High Triangularity ELMy H-mode Plasmas by : C. Giroud
Download or read book Integration of a Radiative Divertor for Heat Load Control Into JET High Triangularity ELMy H-mode Plasmas written by C. Giroud and published by . This book was released on 2012* with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Experiments on JET with a carbon-fibre composite wall have explored the reduction of steady-state power load in an ELMy H-mode scenario at high Greenwald fraction ~0.8, constant power and close to the L to H transition. This paper reports a systematic study of power load reduction due to the effect of fuelling in combination with seeding over a wide range of pedestal density ((4-8) × 1019 m-3) with detailed documentation of divertor, pedestal and main plasma conditions, as well as a comparative study of two extrinsic impurity nitrogen and neon. It also reports the impact of steady-state power load reduction on the overall plasma behaviour, as well as possible control parameters to increase fuel purity. Conditions from attached to fully detached divertor were obtained during this study. These experiments provide reference plasmas for comparison with a future JET Be first wall and an all W divertor where the power load reduction is mandatory for operation."--Abstract.
Book Synopsis Theory of Fusion Plasmas by : Olivier Sauter
Download or read book Theory of Fusion Plasmas written by Olivier Sauter and published by American Institute of Physics. This book was released on 2008-12-02 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Joint Varenna-Lausanne International Workshop on Theory of Fusion Plasmas takes place every other year in a place particularly favorable for informal and in depth discussions. Invited and contributed papers present state-of-the art researches in theoretical plasma physics, covering all domains relevant to fusion plasmas. This workshop always allows a fruitful mix of experienced researchers and students, to allow for a better understanding of the key theoretical physics models and applications, such as: Theoretical issues related to burning plasmas; Anomalous Transport (Turbulence, Coherent Structures, Microinstabilities) RF Heating and Current Drive; Macroinstabilities; Plasma-Edge Physics and Divertors; Fast particles instabilities.
Book Synopsis Iter Physics by : C Wendell Horton, Jr
Download or read book Iter Physics written by C Wendell Horton, Jr and published by World Scientific. This book was released on 2015-06-25 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt: The promise of a vast and clean source of thermal power drove physics research for over fifty years and has finally come to collimation with the international consortium led by the European Union and Japan, with an agreement from seven countries to build a definitive test of fusion power in ITER. It happened because scientists since the Manhattan project have envisioned controlled nuclear fusion in obtaining energy with no carbon dioxide emissions and no toxic nuclear waste products.This large toroidal magnetic confinement ITER machine is described from confinement process to advanced physics of plasma-wall interactions, where pulses erupt from core plasma blistering the machine walls. Emissions from the walls reduce the core temperature which must remain ten times hotter than the 15 million degree core solar temperature to maintain ITER fusion power. The huge temperature gradient from core to wall that drives intense plasma turbulence is described in detail.Also explained are the methods designed to limit the growth of small magnetic islands, the growth of edge localized plasma plumes and the solid state physics limits of the stainless steel walls of the confinement vessel from the burning plasma. Designs of the wall coatings and the special 'exhaust pipe' for spent hot plasma are provided in two chapters. And the issues associated with high-energy neutrons — about 10 times higher than in fission reactions — and how they are managed in ITER, are detailed.
Book Synopsis Compatibility of the Radiating Divertor with High Performance Plasmas in DIII-D. by : S. Allen
Download or read book Compatibility of the Radiating Divertor with High Performance Plasmas in DIII-D. written by S. Allen and published by . This book was released on 2005 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: Excessive thermal power loading on the divertor structures presents a design difficulty for future-generation, high powered tokamaks. This difficulty may be mitigated by ''seeding'' the divertor with impurities which radiate a significant fraction of the power upstream of the divertor targets. For this ''radiating divertor'' concept to be practical, however, the confinement and stability of the plasma cannot be compromised by excessive leakage of the seeded impurities into the core plasma. One proposed way of reducing impurity influx is to enhance the directed scrape-off layer (SOL) flow of deuterium ions toward the divertor [1-5]. We report here on the successful application of the radiating divertor scenario to high performance plasma operation in a DIII-D ''hybrid'' H-mode regime. The ''hybrid'' regime [6,7] has many features in common with conventional ELMing H-mode regimes, such as high confinement, e.g., H{sub ITER89P}> 2, where H{sub ITER89P} is the energy confinement normalized to the 1989 ITER L-mode scaling [8]. The main difference is the absence of sawtooth activity in the hybrid. Argon was selected as the seeded impurity for this experiment because argon radiates effectively at both the divertor and pedestal temperatures found in DIII-D hybrid H-mode operation and has a relatively short ionization mean free path. Carbon is also present as the dominant intrinsic impurity in DIII-D discharges. The geometry of this experiment is shown in Fig. 1. A double-null cross-sectional shape was biased upward (dRsep = +1.0 cm). To increase the deuterium ion flow toward the divertor at the top of the vessel, deuterium gas was introduced near the bottom. Argon was injected directly into the private flux region (PFR) of the upper divertor. In-vessel pumping of deuterium and argon was done by cryopumps located in the two upper divertor plenums, shown in cross-hatching [9]. The upper divertor, which we hereafter will simply refer to as the ''divertor'', is the region lying above the dashed line in Fig. 1, and is relatively ''closed''.
Book Synopsis Pedestal, SOL and Divertor Plasma Properties in DIII-D RMP ELM-Suppressed Discharges at ITER Relevant Edge Collisionality by :
Download or read book Pedestal, SOL and Divertor Plasma Properties in DIII-D RMP ELM-Suppressed Discharges at ITER Relevant Edge Collisionality written by and published by . This book was released on 2007 with total page 25 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Effects of Divertor Geometry and Pumping on Plasma Performance on DIII-D. by :
Download or read book Effects of Divertor Geometry and Pumping on Plasma Performance on DIII-D. written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper reports the status of an ongoing investigation to discern the influence of the divertor and plasma geometry on the confinement of both ELM-free and ELMing discharges in DIII-D. The ultimate goal is to achieve a high-performance core plasma which coexists with an advanced divertor plasma. The divertor plasma must reduce the heat flux to acceptable levels; the current technique disperses the heat flux over a wide area by radiation (a radiative divertor). To date, we have obtained our best performance in double-null (DN) high-triangularity ([delta][approximately] 0.8) ELM-free discharges. As discussed in detail elsewhere, there are several advantages for both the core and divertor plasma with highly-shaped DN operation. Previous radiative-divertor experiments with D[sub 2] injection in DN high-[delta] ELMing H-mode have shown that this configuration is more sensitive to gas puffing ([tau] decreases). Moving the X-point away from the target plate (to[approximately]15 cm above the plate) decreases this sensitivity. Preliminary measurements also indicate that gas puffing reduces the divertor heat flux but does not reduce the plasma pressure along the field line. The up/down heat flux balance can be varied magnetically (by changing the distance between the separatrices), with a slight magnetic imbalance required to balance the heat flux. The overall mission of the Radiative Divertor Project (RDP) is to install a fully pumped and baffled high-[delta] DN divertor. To date, however, both the DIII-D divertor diagnostics and pump were optimized for lower single-null (LSN) low-[delta] ([delta][approximately] 0.4) plasmas, so much of the divertor physics has been performed in LSN; these results are discussed in Section 2. As part of the first phase of the RDP, we have installed a new high-[delta] USN divertor baffle and pump; these results are discussed in Section 3. Both divertor and core parameters are discussed in each case.
Book Synopsis Mitigation of Divertor Heat Flux by High-frequency ELM Pacing with Non-fuel Pellet Injection in DIII-D. by :
Download or read book Mitigation of Divertor Heat Flux by High-frequency ELM Pacing with Non-fuel Pellet Injection in DIII-D. written by and published by . This book was released on 2017 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: Experiments have been conducted on DIII-D investigating high repetition rate injection of non-fuel pellets as a tool for pacing Edge Localized Modes (ELMs) and mitigating their transient divertor heat loads. Effective ELM pacing was obtained with injection of Li granules in different H-mode scenarios, at frequencies 3-5 times larger than the natural ELM frequency, with subsequent reduction of strike-point heat flux. However, in scenarios with high pedestal density (~6 × 1019 m-3), the magnitude of granule triggered ELMs shows a broad distribution, in terms of stored energy loss and peak heat flux, challenging the effectiveness of ELM mitigation. Furthermore, transient heat-flux deposition correlated with granule injections was observed far from the strike-points. As a result, field line tracing suggest this phenomenon to be consistent with particle loss into the mid-plane far scrape-off layer, at toroidal location of the granule injection.
Download or read book Valojuova written by and published by . This book was released on 1945 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Brief van Legazione d'Italia 's-Gravenhage aan Alexander Willem Byvanck (1884-1970) by :
Download or read book Brief van Legazione d'Italia 's-Gravenhage aan Alexander Willem Byvanck (1884-1970) written by and published by . This book was released on 1938 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
