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Book Effects of Resonant Magnetic Perturbations on the STOR M Tokamak Discharges

Download or read book Effects of Resonant Magnetic Perturbations on the STOR M Tokamak Discharges written by Sayf Elgriw and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Toroidal Phasing of Resonant Magnetic Perturbation Effect on Edge Pedestal Transport in the DIII D Tokamak

Download or read book Toroidal Phasing of Resonant Magnetic Perturbation Effect on Edge Pedestal Transport in the DIII D Tokamak written by Theresa M. Wilks and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Resonant Magnetic Perturbation (RMP) fields produced by external control coils are considered a viable option for the suppression of Edge Localized Modes (ELMs) in present and future tokamaks. Repeated reversals of the toroidal phase of the I-coil magnetic field in RMP shot 147170 on DIII-D has generated uniquely different edge pedestal profiles, implying different edge transport phenomena. The causes, trends, and implications of RMP toroidal phase reversal on edge transport is analyzed by comparing various parameters at 0 and 60 degree toroidal phases, with an I-coil mode number of n=3. An analysis of diffusive and non-diffusive transport effects of these magnetic perturbations it the plasma edge pedestal for this RMP shot is characterized by interpreting the ion and electron heat diffusivities, angular momentum transport frequencies, ion diffusion coefficients, and pinch velocities for both phases.

Book Particle Exhaust and Neutral Fueling in Spherical Tokamaks with Resonant Magnetic Perturbation Fields

Download or read book Particle Exhaust and Neutral Fueling in Spherical Tokamaks with Resonant Magnetic Perturbation Fields written by Ian Jacob Waters and published by . This book was released on 2018 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt: Resonant Magnetic Perturbations (RMPs) and Advanced Divertors (ADs) are both promising candidates to be utilized to meet the challenges of power exhaust in future fusion devices. A combination of both approaches is a promising avenue in order to achieve a stable, high performance plasma edge in an integrated way that takes into account divertor heat load limits while allowing for density and impurity control. The latter is of particular importance in spherical tokamaks which feature Edge Localized Mode free high confinement H-mode regimes prone to density rises and core impurity accumulation. The capability to control core densities and particle exhaust in spherical tokamaks needs to be assessed to determine their viability for compact fusion nuclear science facilities. The experimentally observed, density pump-out effect induced by the application of small amplitude RMPs is an important phenomena with respect to density control but its underlying cause is not well understood. One proposed mechanism for this density pump-out is that the opening of formerly confined field lines from the plasma edge enables enhanced parallel exhaust from the core plasma into the scrape-off-layer and to the divertor targets. Further, regions of stochasticity inside the separatrix can lead to enhanced perpendicular transport, even if these field lines do not themselves escape to the wall. Based on magneto-hydrodynamic (MHD) modeling, it has been previously proposed that a particular resonant response to the applied RMP fields--the so called "Edge-Peeling" response--enhances these geometric changes and thus drives enhanced exhaust. How much these mechanisms contribute to the overall pump-out is an open question. Further, how these RMPs impact the fundamental coupling between the plasma core, edge, and scrape-off-layer, through changes to particle fueling and particle exhaust, is the subject of this thesis. The EMC3-EIRENE code is utilized to assess these scenarios on the Mega-Ampere Spherical Tokamak (MAST) and it's upgrade (MAST-U). Initially, work was carried out to validate the theoretical mechanism for enhanced exhaust: that pressure gradients drive flows along open field lines in the plasma edge. Modeling showed that flows generated by local gas puffing are robust to changes in plasma parameters, and ultimately are a fundamental feature that can be experimentally validated. The underlying mechanism of static pressure driven flows was resolved with a 1D model. Modeling was then used to study the impact of RMP fields specifically. The inclusion of plasma response (from a resistive single fluid MHD model) in the RMP fields shows a more moderate response of density and temperature to the RMPs than does a vacuum field approach in MAST lower single null discharges. In this scenario, enhanced exhaust is shown to contribute to the density pump-out, but the modeled confinement changes underpredict the impact expected from analysis of experiments. Applying this same approach in MAST double null discharges--a second test case from experiment--shows that the addition of RMPs with the single fluid Edge-Peeling response does not cause a consistent pump-out signature in the modeling. This numerical finding of no density pump-out is in contrast to experimental observations for such configurations. This is found in spite of the fact that field lines are escaping the confined region, pressure driven flows are formed, and characteristic lobe structures appear in the plasma edge. This study has shown in a consistent manner that pressure driven flows along field lines are a viable mechanism to govern the plasma particle exhaust from the edge reservoir. If 3D magnetic flux bundles generated by RMP fields connect to regions deep inside of the separatrix, the parallel pressure gradient towards divertor targets will drive enhanced particle flux out of the formerly confined region of the plasma. If the length scale of connection is too long such that the parallel pressure gradient can not be maintained, the flow vanishes, and in spite of the nominal 3D structures in the magnetic field, no impact on particle exhaust is seen. This finding is important for the efforts to understand plasma exhaust with RMP fields. The mere existence of the 3D lobes of the separatrix, formed by the RMP fields, is not sufficient to explain the plasma density pump out alone. But for plasma scenarios with short connection length, and magnetic fields characterized by steep radial gradients they are a viable contributor.

Book Resonant external magnetic perturbations on the Texas experimental tokamak

Download or read book Resonant external magnetic perturbations on the Texas experimental tokamak written by William Arthur Craven and published by . This book was released on 1996 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book The Effect of Three Dimensional Shaping on the Ballooning Stability Properties of Stellarator Equilibria and Tokamak Equilibria with Resonant Magnetic Perturbations

Download or read book The Effect of Three Dimensional Shaping on the Ballooning Stability Properties of Stellarator Equilibria and Tokamak Equilibria with Resonant Magnetic Perturbations written by Thomas M. Bird and published by . This book was released on 2011 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Magnetic islandography in Tokamaks

Download or read book Magnetic islandography in Tokamaks written by and published by . This book was released on 1978 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Tearing modes are shown to be responsible for most of the experimentally observed macroscopic behavior of tokamak discharges. The effects of these collective magnetic perturbations on magnetic topology and plasma transport in tokamaks are shown to provide plausible explanations for: internal disruptions (m/n = 1); Mirnov oscillations (m/n = 2,3 ...); and major disruptions (coupling of 2/1-3/2 modes). The nonlinear evolution of the tearing modes is followed with fully three-dimensional computer codes. The effects on plasma confinement of the magnetic islands or stochastic field lines induced by the macroscopic tearing modes are discussed and compared with experiment. Finally, microscopic magnetic perturbations are shown to provide a natural model for the microscopic anomalous transport processes in tokamaks.

Book Co current Toroidal Rotation driven and Turbulent Stresses with Resonant Magnetic Perturbations in the Edge Plasmas of the J TEXT Tokamak

Download or read book Co current Toroidal Rotation driven and Turbulent Stresses with Resonant Magnetic Perturbations in the Edge Plasmas of the J TEXT Tokamak written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Three Dimensional Distortions of the Tokamak Plasma Boundary II Boundary Displacements in the Presence of Resonant Magnetic Perturbations

Download or read book Three Dimensional Distortions of the Tokamak Plasma Boundary II Boundary Displacements in the Presence of Resonant Magnetic Perturbations written by I.T. Chapman and published by . This book was released on 2013 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book The Physics of Edge Resonant Magnetic Perturbations in Hot Tokamak Plasmas

Download or read book The Physics of Edge Resonant Magnetic Perturbations in Hot Tokamak Plasmas written by and published by . This book was released on 2006 with total page 54 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Three Dimensional Distortions of the Tokamak Plasma Boundary

Download or read book Three Dimensional Distortions of the Tokamak Plasma Boundary written by I. T. Chapman and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Investigation of the Effect of Large Core Changes in Toroidal Plasma Rotation and Radial Electric Field on Confinement in H mode Discharges in the DIII D Tokamak

Download or read book Investigation of the Effect of Large Core Changes in Toroidal Plasma Rotation and Radial Electric Field on Confinement in H mode Discharges in the DIII D Tokamak written by and published by . This book was released on 1992 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: The plasma toroidal rotation and the radial electric field in the core ([rho]{approx lt}0.9) of H-mode discharges in DIII-D are greatly altered by the drag produced by application of static, resonant magnetic field perturbations from an external coil (the n = 1 coil''). Transport loss due to turbulent fluctuations can in theory be reduced by E{sub r} shear stabilization or suppression. This is tested experimentally in DIII-D by using the magnetic breaking'' of rotation (with concomitant change in E{sub r}) as an independent control. The magnetic braking produces reversal of the core radial electric field, E{sub r}, and E{sub r} shear. However, the plasma maintains a negative edge ([rho]{approx lt}0.95) E{sub r} and E{sub r} shear and remains in H-mode with insignificant changes in global confinement, density profile and temperature profiles. The H-mode confinement is remarkably robust to the increasing error fields and the slowed toroidal rotation up to the onset of a locked mode which induces a transition to L-mode, the virtual cessation of plasma rotation and large reconnected islands.

Book The Effects of Limiter Current on Tokamak Discharges

Download or read book The Effects of Limiter Current on Tokamak Discharges written by Ned Robert Sauthoff and published by . This book was released on 1972 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt: