US Fusion Research Articles

Building the US National Fusion Grid: results from the National Fusion Collaboratory Project

The US National Fusion Collaboratory Project is developing a persistent infrastructure to enable scientific collaboration for all aspects of magnetic fusion research. The project is creating a robust, user-friendly collaborative software environment and making it available to more than 1000 fusion scientists in 40 institutions who perform magnetic fusion research in the United States. In particular, the project is developing and deploying a national Fusion Energy Sciences Grid (FusionGrid) that is a system for secure sharing of computation, visualization, and data resources over the Internet. The FusionGrid goal is to allow scientists at remote sites to fully participate in experimental and computational activities as if they were working at a common site thereby creating a virtual organization of the US fusion community. The project is funded by the USDOE Office of Science, Scientific Discovery through Advanced Computing (SciDAC) Program and unites fusion and computer science researchers to directly address these challenges.

An Overview of Tokamak Alternatives in the US Fusion Program with the Aim of Fostering Concept Innovation

The US fusion program has operated for just over 50 years, during which time the tokamak has emerged as the most promising vehicle for a burning plasma experiment. However, many other concepts have been built and investigated as alternatives (and possible improvements) to the tokamak, perhaps to make energy from fusion an economic reality sooner. This Paper is an overview of the conventional alternatives to the tokamak and a set of those that are not so conventional with the aim of fostering concept innovation. Usually the devices are grouped into magnetic, inertial, electrostatic, or other categories, with sub-categories. Here, the groupings of conventional- and non-conventional-alternatives are used too. The conventional alternatives are those devices that have been adopted as serious alternatives, and for which many references are immediately available (e.g. rfp, mirror, stellarator, spheromak, laser ICF, etc). The non-conventional alternatives comprise approaches that are not being currently investigated or are worth consideration. In this grouping lie ideas like impact fusion, muon catalyzed fusion, and many historical ones (like the Elmo Bumpy Torus). Several examples of the physics of non-conventional alternatives are presented in summary form as examples of skunkworks in the hope that others will take up the challenge of concept innovation.

Report of the Fusion Simulation Project Steering Committee

The Fusion Simulation Project (FSP) is envisioned as a 15 year, $20M/year multi-institutional project to develop a comprehensive simulation capability for magnetic fusion experiments with a focus on the International Thermonuclear Experimental Reactor (ITER). The FSP would be able to contribute to design decisions, experimental planning and performance optimization for ITER, substantially increasing ITER’s likelihood of success and its value to the US Fusion Program. The FSP would be jointly supported by the DOE Office of Fusion Energy Sciences and the DOE Office of Advanced Scientific Computing Research. The potential for developing this simulation capability rests on the exponential growth of computer power over the last 50 years, the progress in physics understanding developed by the international fusion program and the continued progress in computational mathematics that enables the use of the new “ultra-scale” computers to solve difficult mathematical problems. The initial concept for the FSP was developed by the Fusion Energy Sciences Advisory Committee Integrated Simulation and Optimization of Fusion Systems Subcommittee (J. Dahlburg and J. Corones, et al., J. Fusion Energy, 20(4), 135–196.). The DOE asked the FSP Steering Committee to develop a project vision, a governance concept and a roadmap for the FSP. The Committee recommends that the FSP consist of three elements: a production component, a research and integration component, and a software infrastructure component. The key challenge is developing components that bridge the enormous distance and time scales involved with the disparate physics elements of tokamak performance. The committee recommended that this challenge be met through “Focused Integration Initiatives” that would first seek to integrate different physics packages with disparate distance and time scales. An example is the integration of Radio Frequency (RF) Current Drive and Magnetohydrodynamics (MHD) components to produce an integrated capability to simulate the use of RF current drive to suppress MHD instabilities. This report also defines the requirements for a governance structure. The FSP Steering Committee judged that the project begin with a conceptual design phase lasting one or two years and be followed by a staged ramp-up over a few years to the full funding level.

US fusion program requirements for superconducting magnet research

Future superconducting magnets for fusion applications require improvements in materials and components to significantly enhance the feasibility and attractiveness of fusion reactors as an energy source. These improvements will derive from research and development carried out at government laboratories, universities, and in industry. Research and development carried out under the DOE Office of Fusion Energy Sciences SBIR's and STTR's can provide a significant contribution to this effort by encouraging small businesses to focus on areas of high critical current density superconductors with low to moderate ac losses, superconductors with both high and low stabilizer fraction, superconducting cables with high copper strand fractions, insulation systems that are radiation-resistant with low gas evolution and suitable for vacuum-pressure impregnation (VPI) of coils, and novel quench detectors and other types of advanced magnet system monitoring instrumentation.

A culture of safety : Wilpert, B. and Itoigawa, N. Nuclear Engineering, 2002, 47, (574), 28–30

Under the US Fusion Nuclear Science and Technology program, we selected the Dual Coolant Lead Lithium (DCLL) concept as our primary Test Blanket Module (TBM) for testing in ITER. The DCLL blanket concept has the potential to be a high-performance DEMO blanket design with a projected thermal efficiency of >40%. Reduced activation ferritic/martensitic (RAF/M) steel is used as the structural material. Helium is used to cool the first wall and blanket structure, and the self-cooled Pb-17Li breeder is circulated for power conversion and for tritium extraction. A SiC-based flow channel insert (FCI) is used as an electrical insulator for magnetohydrodynamic pressure drop reduction from the circulating Pb-17Li and as a thermal insulator to separate the high-temperature Pb-17Li (∼650–700 °C) from the RAF/M structure, which has a corrosion temperature limit of ∼480 °C. The RAF/M material must also operate at temperatures above 350 °C but less than 550 °C. We are continuing the development of the mechanical design and performing neutronics, structural and thermal hydraulics analyses of the DCLL TBM module. Prototypical FCI structures were fabricated and further attention was paid to MHD effects and the design of the inboard blanket for DEMO. We are also making progress on related R&D needs to address key areas. This paper is a summary report on the progress and results of recent DCLL TBM development activities.

FIRE, a next step option for magnetic fusion

The next major frontier in magnetic fusion physics is to explore and understand the strong non-linear coupling among confinement, MHD stability, self-heating, edge physics and wave-particle interactions that is fundamental to fusion plasma behavior. The Fusion Ignition Research Experiment (FIRE) design study has been undertaken to define the lowest cost facility to attain, explore, understand and optimize magnetically confined fusion-dominated plasmas. FIRE is envisioned as an extension of the existing advanced tokamak (AT) program that could lead to an attractive magnetic fusion reactor. FIRE activities have focused on the physics and engineering assessment of a compact, high-field tokamak with the capability of achieving Q≈10 in the Elmy H-mode for a duration of ∼1.5 plasma current redistribution times (skin times) during an initial burning plasma science phase, and the flexibility to add AT hardware (e.g. lower hybrid current drive) later. The configuration chosen for FIRE is similar to that of ARIES-RS, the US Fusion Power Plant study utilizing an AT reactor. The key ‘AT’ features are: strong plasma shaping, double null pumping divertors, low toroidal field (TF) ripple (<0.3%), internal control coils and space for wall stabilization capabilities. The reference design point is R o=2.14 m, a=0.595 m, B t( R o)=10 T, I p=7.7 MA with a flat top time of 20 s for 150 MW of fusion power. The baseline magnetic fields and pulse lengths can be provided by wedged BeCu/OFHC TF coils and OFHC poloidal field (PF) coils that are pre-cooled to 80 K prior to the pulse and allowed to warm up to 373 K at the end of the pulse. A longer term goal of FIRE is to explore AT regimes sustained by non-inductive current drive (e.g. lower hybrid current drive) at high fusion gain ( Q>5) for a duration of one to three current redistribution times.

Future directions in US fusion safety and environmental activities

Over the last 30 years, the US fusion program has been a program with a focused energy mission. In recent years, the mission has changed to one that is centered on advancing plasma science, fusion science and fusion technology — the knowledge base needed for an economically and environmentally attractive fusion energy source. In this paper, we discuss the future directions of US fusion safety and environmental R&D and design support activities that are being taken in response to this change in overall mission.

Engineering Status of the Fusion Ignition Research Experiment (FIRE)

FIRE is a compact, high field tokamak being studied as an option for the next step in the US magnetic fusion energy program. FIRE's programmatic mission is to attain, explore, understand, and optimize alpha-dominated plasmas to provide the knowledge necessary for the design of attractive magnetic fusion energy systems. This study began in 1999 with broad participation of the US fusion community, including several industrial participants. The design under development has a major radius of 2 m, a minor radius of 0.525 m, a field on axis of 10T and capability to operate at 12T with upgrades to power supplies. Toroidal and poloidal field magnets are inertially cooled with liquid nitrogen. An important goal for FIRE is a total project cost in the $1B range. This paper presents an overview of the engineering details which were developed during the FIRE preconceptual design study in FY99 and 00.

High temperature superconducting levitation coil for the Levitated Dipole Experiment (LDX)

The Levitated Dipole Experiment (LDX) is an innovative approach to explore the magnetic confinement of fusion plasmas. A superconducting solenoid (floating coil) is magnetically levitated for up to 8 hours in the center of a 5-meter diameter vacuum vessel. This coil is supported by a levitating coil (L-Coil) on top of the vacuum vessel. In the initial machine design, this levitating coil was a water-cooled copper solenoid, and was the experiment's single largest load on the available water system. The main benefit of using a high temperature superconducting coil is the ability to apply more auxiliary heating power to the plasma. However, this coil will also be the first high temperature superconducting coil to be used in a US fusion program experiment. The high temperature superconducting L-Coil is a solenoid, using a two-in-hand winding of a commercially available 0.17 mm/spl times/3.1 mm tape by American Superconductor Corporation with a critical current of 62 A at 77 K and self-field. The L-Coil will be operated at 0.9 T and 20 K. The L-Coil has a protection circuit that not only protects it against overheating in the event of quench, but also against F-Coil collision in the event of a control failure.

Advances in fusion technology

The US fusion technology program is an essential element in the development of the knowledge base for an attractive fusion power source. The technology program incorporates both near and long term R&D, contributes to material and engineering sciences as well as technology development, ranges from hardware production to theory and modeling, contributes significantly to spin-off applications, and performs global systems assessments and focused design studies.

The Java interface of MDSplus: towards a unified approach for local and remote data access

The paper presents the main design concepts of the new Java interface of the MDSplus system, a data acquisition system currently in use in several fusion devices that is becoming the standard ‘de facto’ for data access in US fusion laboratories. The interface is currently composed of two tools, which represent the extension of the two original, X-Windows-based MDSplus interface tools. The first one, called jScope, provides interactive display of stored waveforms. The second one, called jTraverser, provides graphical support for navigation into the tree structure of the pulse files and for the set-up of experiment devices. Though both tools support network communication, remote data access has been considered as a key issue for jScope, in order to make it a general purpose tool for data display, which can be connected to a variety of experiments. Our experience in the development of these tools confirmed the widespread concept about the promising features of the Java language. In particular, the object oriented organization of the language and the rich set of support classes allowed an impressive reduction in the time required for development and testing.

Troubled US fusion project receives cash injection

Washington The US Department of Energy has agreed to provide more funds for the building of the National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory in California.

US fusion scientists seeking a fresh start

After years of budget cuts and internal division, things are looking up for US fusion research. At a recent meeting,the community began work on a common agenda, and tried to present a united front to funding agencies.

A meeting of parallel paths for US fusion?

washington The United States is seeking to integrate research into two rival approaches to fusion power: magnetic and inertial confinement.

The US DOE program for inertial fusion energy

Inertial Fusion Energy (IFE) is viewed by the US fusion community as a promising alternative and, thus, is a “proper and important component” in the restructured US fusion energy sciences program. The office of Fusion Energy Sciences in DOE continues to support Heavy Ion Fusion (HIF) research and development, but with delayed plans for any major construction, due to US government budget tightening.

Fusion researchers seek US role as partner in EU's JET facility

washington Prominent US fusion scientists want the United States to become a partner in the world's largest research facility for plasma physics, the European Union's Joint European Torus (JET) in the United Kingdom.

Panel backs closure of US fusion machine

Panel backs closure of US fusion machine

US fusion researchers brace for major cuts

US fusion researchers brace for major cuts

Irradiation creep and swelling of the US fusion heats of HT9 and 9Cr-1Mo to 208 dpa at ~ 400°C

The irradiation creep and swelling behaviors of the fusion heats of HT9 and 9Cr-1Mo at ~ 400°C have been measured to exposures as large as 208 dpa, using both diametral and density measurements of helium-pressurized creep tubes. Void swelling was found in both alloys at 208 dpa to occur at rates of 0.012%/dpa or less, with the swelling of HT9 exhibiting a larger degree of stress enhancement than 9Cr-1Mo. The creep rate of HT9 is rather nonlinear in its response to hoop stress level in the range 0–200 MPa, but 9Cr-1Mo exhibits only slightly greater than linear behavior with stress level. The creep compliance and creep-swelling coupling coefficient for 9Cr-1Mo are consistent with values obtained for other steels.

Overview of U.S. fusion energy programs: January 1993

The US Fusion Program is in {open_quotes}Transition.{close_quotes} This happens so infrequently that no one knows exactly what to expect; it makes everyone a little skittish. Program leadership does make a difference; Secretary Watkins was a positive force for fusion. Energy Research Director Happer remains in his position and is a positive force for scientific quality. Secretary O`Leary has stated that {open_quotes}Fusion energy holds great promise as an element of the nation`s long-term energy supply.{close_quotes} While new leaders may seek new directions with important implications for fusion, it seems reasonable to expect that, for fusion, such changes are likely to emerge slowly. Thus the assumption now is that the fusion priorities remain unchanged. In the spirit of optimism surrounding the new administration, the Fusion Energy Program`s intention is to make as much progress as possible on the course presently established.