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Mission and Readiness Assessment for Fusion Nuclear Facilities

Description: Magnetic fusion development toward DEMO will most likely require a number of fusion nuclear facilities (FNF), intermediate between ITER and DEMO, to test and validate plasma and nuclear technologies and to advance the level of system integration. The FNF mission space is wide, ranging from basic materials research to net electricity demonstration, so there is correspondingly a choice among machine options, scope, and risk in planning such a step. Readiness requirements to proceed with a DEMO ar… more
Date: December 12, 2012
Creator: Neilson, G. H.; Brown, T. G.; Gates, D. A.; Kessel, C. E.; Menard, J. E.; Prager, S. C. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Progress Toward Attractive Stellarators

Description: The quasi-axisymmetric stellarator (QAS) concept offers a promising path to a more compact stellarator reactor, closer in linear dimensions to tokamak reactors than previous stellarator designs. Concept improvements are needed, however, to make it more maintainable and more compatible with high plant availability. Using the ARIES-CS design as a starting point, compact stellarator designs with improved maintenance characteristics have been developed. While the ARIES-CS features a through-the-por… more
Date: January 5, 2011
Creator: Neilson, G. H.; Brown, T. G.; Gates, D. A.; Lu, K. P.; Zarnstorff, M. C.; Boozer, A. H. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Engineering Accomplishments in the Construction of NCSX

Description: The National Compact Stellarator Experiment (NCSX) was designed to test a compact, quasiaxisymmetric stellarator configuration. Flexibility and accurate realization of its complex 3D geometry were key requirements affecting the design and construction. While the project was terminated before completing construction, there were significant engineering accomplishments in design, fabrication, and assembly. The design of the stellarator core device was completed. All of the modular coils, toroidal … more
Date: September 1, 2008
Creator: Neilson, G. H.; Heitzenroeder, P. J.; Nelson, B. E.; Reiersen, W. T.; Brooks, A.; Brown, T. G. et al.
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Partner: UNT Libraries Government Documents Department
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Magnetic Field Line Tracing Calculations for Conceptual PFC Design in the National Compact Stellarator Experiment

Description: The National Compact Stellarator Experiment (NCSX) is a three-field period compact stellarator presently in the construction phase at Princeton, NJ. The design parameters of the device are major radius R=1.4m, average minor radius <a> = 0.32m, 1.2 {le} toroidal field (B{sub t}) {le} 1.7 T, and auxiliary input power up to 12 MW with neutral beams and radio-frequency heating. The NCSX average aspect ratio <R/a> of 4.4 lies well below present stellarator experiments and designs, enabli… more
Date: June 12, 2006
Creator: Maingi, R; Kaiser, T; Hill, D N; Lyon, J F; Monticello, D & Zarnstorff, M C
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Using E-beam Mapping to Detect Coil Misalignment in NCSX

Description: Following assembly of the NCSX device, a program of e-beam mapping experiments is planned to validate the accuracy of the construction and assembly of the NCSX coil systems. To aid in the development of requirements for the e-beam mapping hardware and machine requirements, simulations of the e-beam mapping experiments, including various coil misalignments, have been done. The magnetic flux surface configuration was constructed using a numerical code, based on the Biot-Savart law, to calculate t… more
Date: October 18, 2005
Creator: Fredrickson E, Georgiyevskiy A, Rudakov V, Zarnstorff MC
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Equilibrium and Stability for the Aries Compact Stellerator Reactor

Description: Equilibrium and ideal magnetohydrodynamic (MHD) stability studies are reported for Compact Stellarator (ARIES-CS) reactor design equilibria based on a scaled three-period NCSX configuration and a two-period quasi-axisymmetric variant, the MHH2 stellarator. With a stabilizing shell at about twice the minor radius, robustly stable equilibria up to {beta}=6% are achievable. Recent experiments raise questions as to the applicability of linear MHD stability in stellarators since the predicted stabil… more
Date: June 1, 2004
Creator: Turnbull, A. D.; Lao, L. L.; Cooper, W. A.; Fu, G. Y.; Garabedian, P.; Ku, L. P. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Constructing Integrable High-pressure Full-current Free-boundary Stellarator Magnetohydrodynamic Equilibrium Solutions

Description: For the (non-axisymmetric) stellarator class of plasma confinement devices to be feasible candidates for fusion power stations it is essential that, to a good approximation, the magnetic field lines lie on nested flux surfaces; however, the inherent lack of a continuous symmetry implies that magnetic islands responsible for breaking the smooth topology of the flux surfaces are guaranteed to exist. Thus, the suppression of magnetic islands is a critical issue for stellarator design, particularly… more
Date: September 15, 2003
Creator: Hudson, S. R.; Monticello, D. A.; Reiman, A. H.; Strickler, D. J.; Hirshman, S. P.; Ku, L. P. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Eliminating Islands in High-pressure Free-boundary Stellarator Magnetohydrodynamic Equilibrium Solutions

Description: Magnetic islands in free-boundary stellarator equilibria are suppressed using a procedure that iterates the plasma equilibrium equations and, at each iteration, adjusts the coil geometry to cancel resonant fields produced by the plasma. The coils are constrained to satisfy certain measures of engineering acceptability and the plasma is constrained to ensure kink stability. As the iterations continue, the coil geometry and the plasma simultaneously converge to an equilibrium in which the island … more
Date: November 19, 2002
Creator: Hudson, S. R.; Monticello, D. A.; Reiman, A. H.; Boozer, A. H.; Strickler, D. J.; Hirshman, S. P. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Physics Considerations in the Design of NCSX

Description: Compact stellarators have the potential to make steady-state, disruption-free magnetic fusion systems with beta approximately 5% and relatively low aspect ratio (R/<a> < 4.5) compared to most drift-optimized stellarators. Magnetic quasi-symmetry can be used to reduce orbit losses. The National Compact Stellarator Experiment (NCSX) is designed to test compact stellarator physics in a high-beta quasi-axisymmetric configuration and to determine the conditions for high-beta disruption-free… more
Date: October 9, 2002
Creator: Neilson, G. H.; Zarnstorff, M. C.; Ku, L. P.; Lazarus, E. A.; Mioduszewski, P. K.; Fenstermacher, M. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Flexibility and Robustness Calculations for NCSX

Description: The National Compact Stellarator Experiment (NCSX) will study the physics of low aspect ratio, high beta quasi-axisymmetric stellarators. In order to achieve the scientific goals of the NCSX mission, the device must be capable of supporting a wide range of variations in plasma configuration about a reference equilibrium. Numerical experiments are presented which demonstrate this capability.
Date: June 6, 2002
Creator: Pomphrey, N.; Hatcher, R.; Hirshman, S. P.; Hudson, S.; Ku, L. P.; Lazarus, E. A. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Physics Design of the National Compact Stellarator Experiment

Description: Compact quasi-axisymmetric stellarators offer the possibility of combining the steady-state low-recirculating power, external control, and disruption resilience of previous stellarators with the low-aspect ratio, high beta-limit, and good confinement of advanced tokamaks. Quasi-axisymmetric equilibria have been developed for the proposed National Compact Stellarator Experiment (NCSX) with average aspect ratio approximately 4.4 and average elongation approximately 1.8. Even with bootstrap-curren… more
Date: February 21, 2002
Creator: Neilson, G.H.; Zarnstorff, M.C.; Lyon, J.F. & Team, the NCSX
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Physics of Compact Advanced Stellarators

Description: Compact optimized stellarators offer novel solutions for confining high-beta plasmas and developing magnetic confinement fusion. The 3-D plasma shape can be designed to enhance the MHD stability without feedback or nearby conducting structures and provide drift-orbit confinement similar to tokamaks. These configurations offer the possibility of combining the steady-state low-recirculating power, external control, and disruption resilience of previous stellarators with the low-aspect ratio, high… more
Date: August 14, 2001
Creator: Zarnstorff, M. C.; Berry, L. A.; Brooks, A.; Fredrickson, E.; Fu, G. Y.; Hirshman, S. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Physics Issues in the Design of Low Aspect-Ratio, High-Beta, Quasi-Axisymmetric Stellarators

Description: Compact stellarators have the potential to combine the best features of the stellarator and the advanced tokamak, offering steady state operation without current drive and potentially without disruptions at an aspect ratio similar to tokamaks. A quasi-axisymmetric stellarator is developed that is consistent with the boot-strap current and passively stable to the ballooning, kink, Mercier, vertical, and neoclassical tearing modes at b=4.1 % without need for conducting walls or external feedback.… more
Date: November 16, 2000
Creator: Zarnstorff, M. C.; Berry, L. A.; Boozer, A.; Brooks, A. & Cooper, W. A.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Stability and transport in compact quasi-axisymmetric stellarators

Description: The potential performance and flexibility of a compact, quasi-axisymmetric (QAS) stellarator design, has been addressed by studying the effects of varied pressure and rotational transform profiles on the global, ideal magnetohydrodynamic (MHD) stability and the energetic particle transport. The CAS3D and TERPSICHORE code packages were used in the MHD studies while the ORBITMN/ORBIT3D code package was used for the transport simulations of the three field period QAS. To assess robust performance … more
Date: July 7, 2000
Creator: Redi, M. H.; Cooper, W. A.; Diallo, A.; Fu, G. Y.; Nuehrenberg, C.; Reiman, A. H. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Physics Basis for High-Beta, Low-Aspect-Ratio Stellarator Experiments

Description: High-beta, low-aspect-ratio (compact) stellarators are promising solutions to the problem of developing a magnetic plasma configuration for magnetic fusion power plants that can be sustained in steady-state without disrupting. These concepts combine features of stellarators and advanced tokamaks and have aspect ratios similar to those of tokamaks (2-4). They are based on computed plasma configurations that are shaped in three dimensions to provide desired stability and transport properties. Exp… more
Date: November 1, 1999
Creator: Brooks, A.; Reiman, A.H.; Neilson, G.H.; Zarnstorff, M.C. & al, et
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Energetic Particle Transport in Compact Quasi-axisymmetric Stellarators

Description: Hamiltonian coordinate, guiding-center code calculations of the confinement of suprathermal ions in quasi-axisymmetric stellarator (QAS) designs have been carried out to evaluate the attractiveness of compact configurations which are optimized for ballooning stability. A new stellarator particle-following code is used to predict ion loss rates and particle confinement for thermal and neutral beam ions in a small experiment with R = 145 cm, B = 1-2 T and for alpha particles in a reactor-size dev… more
Date: March 1, 1999
Creator: Redi, M. H.; Mynick, H. E.; Suewattana, M.; White, R. B.; Zarnstorff, M. C.; Isaev, M. Yu. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Core Poloidal Rotation and Internal Trnasport Barrier Formation in TFTR

Description: Impurity poloidal rotation velocities have been measured in the core of TFTR plasmas using a new spectroscopic diagnostic. Two types of transitions to enhanced confinement in reversed shear plasmas are examined. A bifurcation in carbon poloidal rotation is observed to occur before the transition to enhanced confinement for one of these types, while other measured plasmas parameters remain constant. A narrow radial region with reversed poloidal rotation and rotational shear is established 60-100… more
Date: January 1, 1998
Creator: Synakowski, E.J.; Levinton, F.M.; Zarnstorff, M.C.; Bell, R.E.; Batha, S.H. & al, et
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Transport Physics in Reversed Shear Plasmas

Description: Reversed magnetic shear is considered a good candidate for improving the tokamak concept because it has the potential to stabilize MHD instabilities and reduce particle and energy transport. With reduced transport the high pressure gradient would generate a strong off-axis bootstrap current and could sustain a hollow current density profile. Such a combination of favorable conditions could lead to an attractive steady-state tokamak configuration. Indeed, a new tokamak confinement regime with re… more
Date: December 31, 1997
Creator: Levinton, F. M.; Batha, S. H.; Beer, M. A.; Bell, M. G.; Budny, R. V.; Efthimion, P. C. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Effects of orbit squeezing on ion transport processes close to magnetic axis

Description: It is shown that ion thermal conductivity close to the magnetic axis in tokamaks is reduced by a factor of {vert_bar}S{vert_bar}{sup 5/3} if (M{sub i}/M{sub e}){sup 2/3}(T{sub e}/T{sub i}){sup 4/3}/{vert_bar}S{vert_bar}{sup 5/3} {much_gt} 1. Here, S is the orbit squeezing factor, M{sub i}(M{sub e}) is the ion (electron) mass, and T{sub i}(Te{sub e}) is the ion (electron) temperature. The reduction reflects both the increase of the fraction of trapped particles by a factor of {vert_bar}S{vert_ba… more
Date: January 1997
Creator: Shaing, K. C.; Hazeltine, R. D. & Zarnstorff, M. C.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Local tests of parallel electrical resistivity in the Tokamak Fusion Test Reactor

Description: The motional Stark effect (MSE) polarimeter measures the local magnetic field pitch angle, proportional to the ratio of the poloidal to toroidal magnetic fields, in the Tokamak Fusion Test Reactor (TFTR). The authors have used the polarimeter to measure the temporal evolution of the local value of the magnetic field pitch angle during large changes in the current profile such as during a current ramp or discharge initiation. The measured evolution is compared to the evolution predicted by class… more
Date: January 1, 1997
Creator: Batha, S. H.; Levinton, F. M.; Ramsey, A. T.; Schmidt, G. L. & Zarnstorff, M. C.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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The effect of E{sub r} on MSE measurements of q, a new technique for measuring E{sub r}, and a test of the neoclassical electric field

Description: Previous analysis of motional-Stark Effect (MSE) data to measure the q-profile ignored contributions from the plasma electric field. The MSE measurements are shown to be sensitive to the electric field and require significant corrections for plasmas with large rotation velocities or pressure gradients. MSE measurements from rotating plasmas on the Tokamak Fusion Test Reactor (TFTR) confirm the significance of these corrections and verify their magnitude. Several attractive configurations are co… more
Date: October 1, 1996
Creator: Zarnstorff, M.C.; Synakowski, E.J.; Levinton, F.M. & Batha, S.H.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Enhanced loss of fast ions during mode conversion ion Bernstein wave heating in TFTR

Description: A strong interaction of fast ions with ion Bernstein waves has been observed in TFTR. It results in a large increase in the fast ion loss rate, and heats the lost particles to several MeV. The lost ions are observed at the passing/trapped boundary and appear to be either DD fusion produced tritons or accelerated D neutral beam ions. Under some conditions, enhanced loss of DT alpha particles is also seen. The losses provide experimental support for some of the elements required for alpha energy … more
Date: December 1, 1995
Creator: Darrow, D. S.; Majeski, R.; Fisch, N. J.; Heeter, R. F.; Herrmann, H. W.; Herrmann, M. C. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Supershot performance with reverse magnetic shear in TFTR

Description: Discharges with large regions of reversed magnetic shear and good energy and particle confinement have been produced in the Tokamak Fusion Test Reactor. These plasmas were created by heating the plasma during a rapid plasma current increase. The stability of these discharges is dependent on the shape of the q profile, in particular the value and location of the minimum value of q. Control of the q profile by optimizing the plasma startup, prelude start time, the neutral-beam directionality duri… more
Date: August 1, 1995
Creator: Batha, S. H.; Levinton, F. M.; Zarnstorff, M. C. & Schmidt, G. L.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Collisional stochastic ripple diffusion of alpha particles and beam ions on TFTR

Description: Predictions for ripple loss of fast ions from TFTR are investigated with a guiding center code including both collisional and ripple effects. A synergistic enhancement of fast ion diffusion is found for toroidal field ripple with collisions. The total loss is calculated to be roughly twice the sum of ripple and collisional losses calculated separately. Discrepancies between measurements and calculations of plasma beta at low current and large major radius are resolved when both effects are incl… more
Date: July 1, 1995
Creator: Redi, M. H.; Zarnstorff, M. C.; White, R. B.; Budny, R. V.; Janos, A. C.; Owens, D. K. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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