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Book Exploration of Spherical Torus Physics in the NSTX Device

Download or read book Exploration of Spherical Torus Physics in the NSTX Device written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The National Spherical Torus Experiment (NSTX) is being built at the Princeton Plasma Physics Laboratory to test the fusion physics principles for the Spherical Torus (ST) concept at the MA level. The NSTX nominal plasma parameters are R[sub 0]= 85 cm, a= 67 cm, R/a greater than or equal to 1.26, B[sub T]= 3 kG, I[sub p]= 1 MA, q[sub 95]= 14, elongation[kappa] less than or equal to 2.2, triangularity[delta] less than or equal to 0.5, and plasma pulse length of up to 5 sec. The plasma heating/current drive (CD) tools are High Harmonic Fast Wave (HHFW) (6 MW, 5 sec), Neutral Beam Injection (NBI) (5 MW, 80 keV, 5 sec), and Coaxial Helicity Injection (CHI). Theoretical calculations predict that NSTX should provide exciting possibilities for exploring a number of important new physics regimes including very high plasma beta, naturally high plasma elongation, high bootstrap current fraction, absolute magnetic well, and high pressure driven sheared flow. In addition, the NSTX program plans to explore fully noninductive plasma start-up, as well as a dispersive scrape-off layer for heat and particle flux handling.

Book Engineering Design of the National Spherical Torus Experiment

Download or read book Engineering Design of the National Spherical Torus Experiment written by C. Neumeyer and published by . This book was released on 2000 with total page 81 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Final Report of the Committee on a Strategic Plan for U S Burning Plasma Research

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 Next Step Spherical Torus Design Studies

Download or read book Next Step Spherical Torus Design Studies written by and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Studies are underway to identify and characterize a design point for a Next Step Spherical Torus (NSST) experiment. This would be a ''Proof of Performance'' device which would follow and build upon the successes of the National Spherical Torus Experiment (NSTX) a ''Proof of Principle'' device which has operated at PPPL since 1999. With the Decontamination and Decommissioning (D & D) of the Tokamak Fusion Test Reactor (TFTR) nearly completed, the TFTR test cell and facility will soon be available for a device such as NSST. By utilizing the TFTR test cell, NSST can be constructed for a relatively low cost on a short time scale. In addition, while furthering spherical torus (ST) research, this device could achieve modest fusion power gain for short-pulse lengths, a significant step toward future large burning plasma devices now under discussion in the fusion community. The selected design point is Q=2 at HH=1.4, P subscript ''fusion''=60 MW, 5 second pulse, with R subscript ''0''=1.5 m, A=1.6, I subscript ''p''=10vMA, B subscript ''t''=2.6 T, CS flux=16 weber. Most of the research would be conducted in D-D, with a limited D-T campaign during the last years of the program.

Book Fusion Nucl aire

Download or read book Fusion Nucl aire written by and published by . This book was released on 2005 with total page 714 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Operational Limits in the National Spherical Torus Experiment

Download or read book Operational Limits in the National Spherical Torus Experiment written by S. M. Kaye and published by . This book was released on 2000 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Progress Towards High Performance Steady State Spherical Torus

Download or read book Progress Towards High Performance Steady State Spherical Torus written by and published by . This book was released on 2004 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: Research on the spherical torus (or spherical tokamak) (ST) is being pursued to explore the scientific benefits of modifying the field line structure from that in more moderate aspect ratio devices, such as the conventional tokamak. The ST experiments are being conducted in various US research facilities including the MA-class National Spherical Torus Experiment (NSTX) at Princeton, and three medium sized ST research facilities: PEGASUS at University of Wisconsin, HIT-II at University of Washington, and CDX-U at Princeton. In the context of the fusion energy development path being formulated in the US, an ST-based Component Test Facility (CTF) and, ultimately a Demo device, are being discussed. For these, it is essential to develop high performance, steady-state operational scenarios. The relevant scientific issues are energy confinement, MHD stability at high beta ([beta]), non-inductive sustainment, Ohmic-solenoid-free start-up, and power and particle handling. In the confinement area, the NSTX experiments have shown that the confinement can be up to 50% better than the ITER-98-pby2 H-mode scaling, consistent with the requirements for an ST-based CTF and Demo. In NSTX, CTF-relevant average toroidal beta values [beta]{sub T} of up to 35% with a near unity central [beta]{sub T} have been obtained. NSTX will be exploring advanced regimes where [beta]{sub T} up to 40% can be sustained through active stabilization of resistive wall modes. To date, the most successful technique for non-inductive sustainment in NSTX is the high beta poloidal regime, where discharges with a high non-inductive fraction (≈60% bootstrap current+NBI current drive) were sustained over the resistive skin time. Research on radio-frequency (RF) based heating and current drive utilizing high harmonic fastwave and electron Bernstein wave is also pursued on NSTX, PEGASUS, and CDX-U. For non-inductive start-up, the coaxial helicity injection, developed in HIT/HIT-II, has been adopted on NSTX to test the method up to I{sub P} ≈500 kA. In parallel, start-up using a RF current drive and only external poloidal field coils are being developed on NSTX. The area of power and particle handling is expected to be challenging because of the higher power density expected in the ST relative to that in conventional aspect-ratio tokamaks. Due to its promise for power and particle handling, liquid lithium is being studied in CDX-U as a potential plasma-facing surface for a fusion reactor.

Book Overview of the Initial NSTX Experimental Results

Download or read book Overview of the Initial NSTX Experimental Results written by and published by . This book was released on 2000 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The main aim of the National Spherical Torus Experiment (NSTX) is to establish the fusion physics principles of the spherical torus (ST) concept. The NSTX device began plasma operations in February 1999 and the plasma current Ip was successfully brought up to the design value of 1 MA on 14 December 1999. The planned plasma shaping parameters, elongation = 1:6{2.2 and triangularity = 0:2{0.4, were achieved in inner wall limited, and single null and double null diverted congurations. The coaxial helicity injection (CHI) and high harmonic fast wave (HHFW) experiments were also initiated. CHI current of 27 kA produced up to 260 kA toroidal current without using an ohmic solenoid. With the injection of 2.3 MW of HHFW power, using 12 antennas connected to six transmitters, electrons were heated from a central temperature of 400 eV to 900 eV at a central density of 3:5 1013 cm 3, increasing the plasma energy to 59 kJ and the toroidal, T, to 10%. The NBI system commenced operation in September 2000. The initial results with two ion sources (PNBI = 2:8 MW) show good heating, producing a total plasma stored energy of 90 kJ corresponding to T 18% at a plasma current of 1.1 MA.

Book An Overview of Recent Physics Results from NSTX

Download or read book An Overview of Recent Physics Results from NSTX written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Currently, the National Spherical Torus Experiment (NSTX) is being upgraded to operate at twice the toroidal field and plasma current (up to 1 T and 2 MA), with a second, more tangentially aimed neutral beam (NB) for current and rotation control, allowing for pulse lengths up to 5 s. Recent NSTX physics analyses have addressed topics that will allow NSTX-Upgrade to achieve the research goals critical to a Fusion Nuclear Science Facility. These include producing stable, 100% non-inductive operation in high-performance plasmas, assessing plasma-material interface (PMI) solutions to handle the high heat loads expected in the next-step devices and exploring the unique spherical torus (ST) parameter regimes to advance predictive capability. Non-inductive operation and current profile control in NSTX-U will be facilitated by co-axial helicity injection (CHI) as well as radio frequency (RF) and NB heating. CHI studies using NIMROD indicate that the reconnection process is consistent with the 2D Sweet-Parker theory. Full-wave AORSA simulations show that RF power losses in the scrape-off layer (SOL) increase significantly for both NSTX and NSTX-U when the launched waves propagate in the SOL. Moreover, Toroidal Alfven eigenmode avalanches and higher frequency Alfven eigenmodes can affect NB-driven current through energy loss and redistribution of fast ions. The inclusion of rotation and kinetic resonances, which depend on collisionality, is necessary for predicting experimental stability thresholds of fast growing ideal wall and resistive wall modes. Neutral beams and neoclassical toroidal viscosity generated from applied 3D fields can be used as actuators to produce rotation profiles optimized for global stability. DEGAS-2 has been used to study the dependence of gas penetration on SOL temperatures and densities for the MGI system being implemented on the Upgrade for disruption mitigation. PMI studies have focused on the effect of ELMs and 3D fields on plasma detachment and heat flux handling. Simulations indicate that snowflake and impurity seeded radiative divertors are candidates for heat flux mitigation in NSTX-U. Studies of lithium evaporation on graphite surfaces indicate that lithium increases oxygen surface concentrations on graphite, and deuterium-oxygen affinity, which increases deuterium pumping and reduces recycling. In situ and test-stand experiments of lithiated graphite and molybdenum indicate temperature-enhanced sputtering, although that test-stand studies also show the potential for heat flux reduction through lithium vapour shielding. Non-linear gyro kinetic simulations have indicated that ion transport can be enhanced by a shear-flow instability, and that non-local effects are necessary to explain the observed rapid changes in plasma turbulence. Predictive simulations have shown agreement between a microtearing-based reduced transport model and the measured electron temperatures in a microtearing unstable regime. Finally, two Alfven eigenmode-driven fast ion transport models have been developed and successfully benchmarked against NSTX data. Upgrade construction is moving on schedule with initial physics research operation of NSTX-U planned for mid-2015.

Book The National Spherical Torus Experiment NSTX Research Program and Progress Towards High Beta Long PulseOperating Scenarios

Download or read book The National Spherical Torus Experiment NSTX Research Program and Progress Towards High Beta Long PulseOperating Scenarios written by E. J. Synakowski and published by . This book was released on 2002 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Progress Towards High Performance Plasmas in the National Spherical Torus Experiment NSTX

Download or read book Progress Towards High Performance Plasmas in the National Spherical Torus Experiment NSTX written by and published by . This book was released on 2006 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: The major objective of the National Spherical Torus Experiment (NSTX) is to understand basic toroidal confinement physics at low aspect ratio and high [beta]{sub T} in order to advance the spherical torus (ST) concept. In order to do this, NSTX utilizes up to 7.5 MW of neutral beam injection, up to 6 MW of high harmonic fast waves (HHFWs), and it operates with plasma currents up to 1.5 MA and elongations of up to 2.6 at a toroidal field up to 0.45 T. New facility, and diagnostic and modeling capabilities developed over the past two years have enabled the NSTX research team to make significant progress towards establishing this physics basis for future ST devices. Improvements in plasma control have led to more routine operation at high elongation and high [beta]{sub T} (up to ≈ 40%) lasting for many energy confinement times. [beta]{sub T} can be limited by either internal or external modes. The installation of an active error field (EF) correction coil pair has expanded the operating regime at low density and has allowed for initial resonant EF amplification experiments. The determination of the confinement and transport properties of NSTX plasmas has benefited greatly from the implementation of higher spatial resolution kinetic diagnostics. The parametric variation of confinement is similar to that at conventional aspect ratio but with values enhanced relative to those determined from conventional aspect ratio scalings and with a [beta]{sub T} dependence. The transport is highly dependent on details of both the flow and magnetic shear. Core turbulence was measured for the first time in an ST through correlation reflectometry. Non-inductive start-up has been explored using PF-only and transient co-axial helicity injection techniques, resulting in up to 140 kA of toroidal current generated by the latter technique. Calculated bootstrap and beam-driven currents have sustained up to 60% of the flat-top plasma current in NBI discharges. Studies of HHFW absorption have indicated parametric decay of the wave and associated edge thermal ion heating. Energetic particle modes, most notably toroidal Alfven eigenmodes and fishbone-like modes result in fast particle losses, and these instabilities may affect fast ion confinement on devices such as ITER. Finally, a variety of techniques has been developed for fueling and power and particle control.

Book Engineering Overview of the National Spherical Torus Experiment NSTX

Download or read book Engineering Overview of the National Spherical Torus Experiment NSTX written by and published by . This book was released on 1997 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The National Spherical Torus Experiment (NSTX) Project will provide a national facility for the study of plasma confinement, heating, and current drive in a low-aspect-ratio, spherical torus (ST) configuration. The ST configuration is an alternate confinement concept which is characterized by high beta, high elongation, high bootstrap fraction, and low toroidal magnetic field compared to conventional tokamaks. The NSTX is the next-step ST experiment following smaller experiments such as the Princeton Plasma Physics Laboratory CDX-U (Current Drive Experiment-Upgrade), the START (Small Tight Aspect Ratio Tokamak) at Culham Laboratory, UK, and the HIT (Helicity Injected Tokamak) at the University of Washington, and it is smaller in scale to the MAST (Meg-Amp Spherical Tokamak) machine now under construction at Culham. This paper provides a description of the NSTX mission and gives an overview of the main engineering features of the design of the machine and facility and discusses some of the key design solutions.