US Fusion Program Research Articles

Open letter to the associate director for DOE’s Office of Fusion Energy Sciences

We are early-career research scientists and professors, all under 40, who work in plasma and fusion science. We are concerned about the proposed fiscal year 2013 budget for the Office of Fusion Energy Sciences (OFES) in the Department of Energy’s Office of Science and about the future plasma and fusion science funding trajectory it represents.The current US administration has affirmed its “world-class commitment to science,” with the goal of attracting more US students to science and engineering now, and to ITER, the international tokamak fusion project, as it reaches full operating capacity 15 years from now. Those commitments should be applauded, and they should be acted on sensibly to maximize the return on investment for US taxpayers in today’s tough fiscal environment.With a price tag upwards of $20 billion, ITER is the cornerstone of the world’s fusion energy program. It represents a leap forward on the path to a viable fusion reactor. Yet ITER is more than an engineering project. It will have to create, confine, and control a self-sustained, burning plasma. The challenge of studying that plasma state is matched by the anticipation of what we will learn. We have theories of how a burning plasma will behave and how associated heat loads and energetic particles will impact the ITER wall materials. And there is one thing we know: ITER is discovery science, and a burning plasma will produce plenty of surprises once we get there. Some surprises may be advantageous, others will need to be mitigated.US plasma and fusion scientists must be in a position to understand and expand on those new physics insights. The vibrant domestic program must be maintained and nurtured, so that today’s graduate students and postdocs can become experienced scientists and leaders 15 years from now.Instead, the administration’s FY 2013 OFES budget redirects one-sixth of the FY 2012 domestic spending to the ITER project (see Physics Today, June 2012, page 25). If that trend continues, within the next two years hundreds of scientists and engineers at premier US institutions will be laid off. Over time, those layoffs will lead to the permanent loss of some of the brightest young minds from the US plasma and fusion program, and likely from the academic and research communities altogether.The fusion program has a public-image problem: It was supposed to deliver cheap and safe nuclear energy long before many of us young scientists entered the field. But the plasma and fusion program is much broader than energy research. It encompasses the study of supernovae explosions, solar coronal mass ejections, galaxy clusters, wakefield accelerators, the basic complexity of dynamical systems, and many other plasma phenomena.Plasma science, with its enormous breadth, draws on many funding agencies, but the 2007 National Research Council report Plasma Science: Advancing Knowledge in the National Interest has called on the DOE Office of Science to take the stewardship role in guiding the multifaceted and exciting research field forward. The Office of Science must act on this deed of trust and enable us to capitalize on the public curiosity and interest in the 99.9% of the visible universe we call a plasma.The US Congress has consistently said that ITER funding should not come from the domestic fusion program, which is already underfunded, yet the contributions to ITER are threatening to consume the entire domestic OFES-funded program. The proposed FY 2013 US contribution to ITER is $150 million and is scheduled to double or even triple in the next few years. That makes us deeply concerned for the ability of the Office of Science to allow and encourage domestic plasma and fusion research to survive and thrive.The under-40 crowd, those expected to lead our field in the ITER era, respectfully request that you not let the world-leading US plasma and fusion program weaken in comparison to our partners and competitors. Instead, let us capitalize on the taxpayers’ domestic R&D and ITER investments. Let us build a stronger and broader program to advance knowledge in basic plasma and fusion science and to prepare the scientific workforce of this country for the era of burning plasma.In addition to the two of us, 61 other early-career scientists from 27 organizations across the country have signed this letter. The original version, with all its signatories, is available at http://fire.pppl.gov/under_40_letter_2012.pdf.© 2012 American Institute of Physics.

A better option for US fusion program

A better option for US fusion program

Editorial of the Special Historical Issue

This Special Historical Issue contains two papers of historical interest relating to the evolution of the US fusion program in the 1960s. The first, the 1966 AEC Policy and Action Paper on Controlled Thermonuclear Research, was prepared in response to a request from the US congressional (House-Senate) Joint Committee on Atomic Energy and the US House of Representatives Appropriations Committee. The second describes the history of a fusion concept unique to the US program, the Astron. It was first proposed in 1956, began construction in 1958, and ended in 1973. The 1966 policy paper was prepared within the Controlled Thermonuclear Research (CTR) Branch of the AEC’s Division of Research by Amasa S. Bishop and Stephen O. Dean, assisted by Richard F. Post of the Lawrence Livermore National Laboratory (then Lawrence Radiation Laboratory). The AEC was the original predecessor agency of the current US Department of Energy (DOE); its Research Division was the original predecessor of the current DOE Office of Science; and its CTR Branch was the original predecessor of the current DOE Office of Fusion Energy Sciences (OFES). Bishop was the first head of the US fusion program (1953–1956) and wrote the classic early history of fusion in the book Project Sherwood (Addison-Wesley Publishing Company 1958). He worked at the Princeton Plasma Physics Laboratory in the early 1960s, returning to once more head the US fusion program at AEC (1965–1970). He was a recipient of Fusion Power Associates Distinguished Career Award in 1992 and passed away in 1997. Dick Post is a pioneer of the US fusion program, dating back to the mid 1950s. He was the recipient of Fusion Power Associates first Distinguished Career Awards in 1987 and is still active in research. Dean was a member of the AEC CTR Branch (1962–1969) and again 1972–1979, after a 3-year stint at the US Naval Research Laboratory doing experimental research on laserproduced plasmas. He has been President of Fusion Power Associates since 1979. The Policy Paper was transmitted to Congress on July 11, 1966 by then AEC chairman Glenn Seaborg. A copy of the transmittal letter is contained in the paper. The transmittal letter states that the AEC’s General Advisory Committee (GAC) and the President’s Science Advisory Committee (now called PCAST), have reviewed the report and endorse ‘‘the importance of the program and the need for an intensified effort.’’ The report also includes, as appendices, a 1962 review of the CTR program by the AEC’s GAC and a review of the report by a special committee set up by the AEC in late 1965. The report concludes, ‘‘By any standard whatsoever, controlled thermonuclear research must be counted as one of the most challenging and potentially important efforts in the history of mankind.’’ It notes that ‘‘there are also compelling interests of a more basic nature for studying the behavior of plasmas’’ since ‘‘its bearing on other fields of knowledge and on the future activities of mankind may well be profound.’’ The central policy statement in the report reads as follows: ‘‘The AEC program will continue to be motivated by interest in eventually achieving controlled thermonuclear power. It is recognized, however, that there are many benefits which will accrue from an investigation of this vast and largely-unexplored field. As a result, the effort will emphasize not only a detailed understanding of the physics of high temperature plasmas and the means for confining S. O. Dean (&) Fusion Power Associates, Gaithersburg, MD 20879, USA e-mail: fusionpwrassoc@aol.com

Recent accomplishments and future directions in the US Fusion Safety and Environmental Program

The US Fusion Program has long recognized that the safety and environmental (S&E) potential of fusion can be attained by prudent materials selection, judicious design choices and integration of safety requirements into the design of the facility. To achieve this goal, S&E research is focused on understanding the behaviour of the largest sources of radioactive and hazardous materials in a fusion facility, understanding how energy sources in a fusion facility could mobilize those materials, developing integrated state-of-the-art S&E computer codes and risk tools for safety assessment and evaluating S&E issues associated with current fusion designs. In this paper, recent accomplishments are reviewed and future directions outlined.

Summary of US Fusion Program Planning Documents Relating to Innovative Confinement Concepts (1992–2005)

During the 1990’s approximately 15 planning documents were produced by community consensus and by panels of experts. These documents lead to the restructuring of the Office of Fusion Energy (OFE). The OFE adopted joint goals of science and performance and opened a solicitation for Innovative Confinement Concept (ICC) experiments. This paper summarizes the documents that appeared during this time that relate to the ICCs.

Superconducting magnet and conductor research activities in the US fusion program

Fusion research in the United States is sponsored by the Department of Energy's Office of Fusion Energy Sciences (OFES). The OFES sponsors a wide range of programs to advance fusion science, fusion technology, and basic plasma science. Most experimental devices in the US fusion program are constructed using conventional technologies; however, a small portion of the fusion research program is directed towards large scale commercial power generation, which typically relies on superconductor technology to facilitate steady-state operation with high fusion power gain, Q. The superconductor portion of the US fusion research program is limited to a small number of laboratories including the Plasma Science and Fusion Center at MIT, Lawrence Livermore National Laboratory (LLNL), and the Applied Superconductivity Center at University of Wisconsin, Madison. Although Brookhaven National Laboratory (BNL) and Lawrence Berkeley National Laboratory (LBNL) are primarily sponsored by the US's High Energy Physics program, both have made significant contributions to advance the superconductor technology needed for the US fusion program. This paper summarizes recent superconductor activities in the US fusion program.

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.

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.

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.

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.

Irradiation creep in type 316 stainless steel and us PCA with fusion reactor He/dpa levels

Abstract Irradiation creep was investigated in Type 316 stainless steel (316 SS) and US Fusion Program PCA using a tailored spectrum of the Oak Ridge Research Reactor in order to achieve a He/dpa value characteristic of a fusion reactor first wall. Pressurized tubes with stresses of 20 to 470 MPa were irradiated at temperatures of 330, 400, 500, and 600°C. It was found that irradiation creep was independent of temperature in this range and varied linearly with stress at low stresses, but the stress exponent increased to 1.3 and 1.8 for 316 SS and PCA, respectively, at higher stresses. Specimens of PCA irradiated in the ORR and having helium levels up to 200 appm experienced a 3 to 10 times higher creep rate than similar specimens irradiated in the FFTF and having helium levels below 20 appm. The higher creep rates are attributed to either a lower flux or the presence of helium. A mechanism involving interstitial helium-enhanced climb is proposed.

Maintainability Features of the Compact Ignition Tokamak

The Compact Ignition Tokamak (CIT) is a deuterium-tritium (D-T) device envisaged to be the next experimental reactor in the US Fusion Program. The reactor will initially operate in a nonactivated hydrogen phase for approximately two years. This will permit verification of the integrity of the total system and allow hands-on repair to equipment which has experienced shakedown and early operation failures. Once D-T operations commence, reactor maintenance will require remote handling techniques. An evaluation has been completed to determine what maintenance operations must be performed on the CIT. A maintenance philosophy has been developed which is based upon the use of manipulator systems and robotics in the test cell. Replacement of life-limited equipment will be accomplished using a modular design approach for components, with simple remotely operable interfaces. Examples of operations to be done remotely include: (1) replacing of rf antennae and Faraday shields, (2) uncoupling diagnostic and fueling penetrations, (3) removing of all port covers, and (4) replacing first wall armor tiles, optical mirrors, and vacuum windows.