Special Issue "Nuclear Fusion"

Guest Editor
Dr. Stephen O. Dean
Fusion Power Associates, 2 Professional Drive Suite 249, Gaithersburg, MD 20879, USA
Website: http://fusionpower.org/
E-Mail:

Dear Colleagues,

Fusion is the energy source of the Sun and Stars. For over 50 years, scientists all over the world have been seeking to develop a process for tapping fusion energy for use on Earth. Fusion takes place most readily between deuterium and tritium, the two heavy isotopes of hydrogen. A gas of these isotopes, called a plasma, must be heated to temperatures of about 100 million degrees Celsius and kept away from material walls of a chamber for a long enough time to release a practical amount of fusion energy in a continuous or semi-continuous stream. There are several approaches to do this. The two flagship facilities are the magnetically confined international tokamak project (ITER) under construction in France and the National Ignition Facility (NIF), a laser-based facility recently came into operation in the U.S. This issue summarizes some of the latest developments in the quest for fusion energy.

Dr. Stephen O. Dean
Guest Editor

Submission

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Type of Paper: Article
Title: The Fastest Route to Fusion Power on the Grid
Author: Professor Rob Goldston
Affiliation: DOE Princeton University Plasma Physics Laboratory, LSB 319, MS 41, Princeton, NJ 08543, USA; Tel: 609/243-3550, Fax: 609/243-2222, Website: www.pppl.gov
Abstract: While further progress in fundamental understanding of plasmas and in the development of advanced technologies is needed for the most practical implementation of fusion power, the fusion research community is nonetheless being challenged to put net electricity on the grid as quickly as possible. Here we examine a plan in which activities in parallel with ITER in the areas of configuration optimization, plasma-wall interactions, and neutron-interactive materials, together with results from ITER, lead to the rapid construction of a fusion pilot plant that produces net electricity, while continuing to further progress in fusion science and technology.

Type of Paper: Review
Title: Energy resources for future world
Author: Ken Tomabechi
Abstract: Recent survey indicates that in 2005 the world consumed energy of 0.5 ZJ (ZJ = 10²¹ J). If one assumes that future world population to be 10 billions and all the people will consume similar amount of energies to those of the present developed countries, the world will need 1 to 2 ZJ a year. Statistics of future energy resources indicate that the energies recoverable from coal, oil and gas are only 23 ZJ, 6.7 ZJ and 6.4 ZJ. Other energy resources such as solar, wind and etc. are also limited. However, energy from known Uranium resources by breeder reactors is 227 ZJ and that from Lithium by fusion reactors is 180 ZJ. Therefore, development of proper breeders and fusion reactors to supply major part of energies in the future world is important.

Title: Challenges of Magnetic Fusion Technology
Author: Thomas J. Dolan
Affiliation: 100G Talbot Lab, MC-234, University of Illinois at Urbana-Champaign, USA; dolantj@illinois.edu
Abstract: Many advanced technologies are required to facilitate the development of economical fusion power. High-field superconducting magnets use clever methods to overcome the brittle behavior of the materials. High temperature superconductors may result in simpler designs and cost savings. Cryogenic vacuum pumps provide extremely high pumping speeds to remove helium ash. Heating and current drive systems are being developed to control the radial distrubtions of plasma density, temperature, and current density ("profile control") to maximize the energy confinement time and fusion power density. First wall materials must sustain high fluxes of heat and neutrons without failure or trapping of too much tritium. Blankets will breed tritium fuel, remove MegaWatts of heat per square meter, and shield the magnet coils from radiation damage. Development of advanced materials, such as ultrapure vanadium alloys and SiC structures, is very important, and a new neutron source will test their behavior under high neutron fluxes.

Type of Paper: Review
Title: Fifty Years of Magnetic Fusion Research (1958-2008): Brief Historical Overview and Future Trends
Author: Laila A. El-Guebaly
Affiliation: Fusion Technology Institute, University of Wisconsin - Madison, 1500 Engineering Drive, Madison, WI 53706, USA; E-Mail: elguebaly@engr.wisc.edu
Abstract: In the late 1950s, the secrecy surrounding magnetically controlled thermonuclear fusion had been lifted allowing researchers to freely share the technical results and discuss the challenges of harnessing fusion power. There were only four magnetic confinement fusion concepts pursued internationally: tokamak, stellarator, pinch, and mirror. Since the early 1970s, numerous fusion designs have been developed for a wide range of new and old design approaches: tokamaks, stellarators, spherical tori, field-reversed configurations, reversed-field pinches, spheromaks, and tandem mirrors. The D-T fuelled tokamak is regarded worldwide as the most viable candidate to demonstrate fusion energy generation and its program accounts for over 90% of the fusion effort. Numerous power plant studies (>50), extensive R&D programs, more than 100 operating experiments, and an impressive international collaboration led to the current wealth of fusion information and understanding. As a result, fusion promises to be a major part of the energy mix in the 21st century. The philosophy adopted in international fusion designs varies widely in the degree of physics extrapolation, technology readiness, and economic competitiveness. For this reason, the national roadmap to fusion energy is influenced by the timeline anticipated for the development of the essential physics and technologies for Demo and successor power plants. As such, the various fusion roadmaps developed to date take different approaches, depending on the anticipated power plant concept and degree of extrapolation beyond ITER. Several Demos with differing approaches should be built in the US, EU, Japan, China, Russia, Korea, India and other countries to cover the wide range of near-term and advanced fusion systems.

Type of Paper: Review
Title: Tokamak Fusion Research toward Steady-state Operation
Author: Mitsuru Kikuchi
Affiliation: Japan Atomic Energy Agency, Japan; E-Mail: kikuchi.mitsuru@jaea.go.jp
Abstract: World fusion research came to the stage of demonstration of scientific and technological feasibility of fusion energy by ITER using tokamak concept after 50 years of fusion research. In this paper, I review fundamentals of fusion and plasma confinement and the steady state tokamak research world wide to clarify achievements and issues for tokamak power plant. In 1990, we developed a steady-state tokamak reactor concept best utilizing the bootstrap current called SSTR and similar concept ARIES-I from US as well. Since then, significant efforts has been done in major tokamaks such as JT-60U, DIII-D, TFTR, AUG, C-Mod and JET. Despite such efforts, we still have a lot of works to be done in parallel with ITER in the future.

Type of Paper: Review
Title: Plasma Confinement by Pressure of Rotating Magnetic Field
Author: Vladimir Svidzinski^1,2
Affiliations: ¹ Department of Physics, University of Wisconsin-Madison, WI, USA; E-Mail: vsvidzinski@wisc.edu
² Los Alamos National Laboratory, USA
Abstract: Review of plasma confinement concept in which unmagnetized plasma is confined in steady state by pressure of magnetic field surrounding plasma volume and rotating in plane tangential to plasma surface is presented. The frequency of rotation of confining magnetic field is relatively low such that the size of plasma containing device is much smaller than wavelength of electromagnetic wave propagating in vacuum at the same frequency. The confining field is localized in a vacuum layer, or a layer of low loss dielectric, between plasma and a conducting shell, it penetrates plasma on a few skin depths. Device for practical realization of this concept comprises a toroidal conducting shell filled with plasma, with AC voltages applied to insulated cuts in the shell made in poloidal and toroidal directions such that the rotating magnetic field is created in the layer between plasma surface and the inner surface of the shell by AC currents in the shell and image currents on the plasma surface. The voltages applied to the cuts have 90 degrees phase difference and their amplitudes are such that the resultant magnetic vector rotates in the plane tangential to the plasma surface with nearly circular polarization, thus exerting nearly time independent magnetic pressure on the plasma. Toroidal plasma equilibrium and stability are achieved by constraint of conservation of AC magnetic flux amplitude through any section of the layer between plasma surface and conducting shell. Estimates of possible plasma parameters in such plasma confinement devices are made along with a discussion of their potential as a fusion reactor.

Type of Paper: Review
Title: Exploiting Laboratory and Heliophysics Plasma Synergies
Authors: Jill Dahlburg¹, William Amatucci¹, Michael Brown², Vincent Chan³, James Chen¹, Christopher Cothran¹, Damien Chua¹, Russell Dahlburg¹, George Doschek¹, Jan Egedal⁴, Cary Forest⁵, Russell Howard¹, Joseph Huba¹, Jonathan Krall¹, J. Martin Laming¹, Robert Lin⁶, Mark Linton¹, Vyacheslav Lukin¹, Ronald Murphy¹, Cara Rakowski¹, Dennis Socker¹, Allan Tylka¹, Angelos Vourlidas¹, Harry Warren¹ and Brian Wood¹
Affiliations: ¹ Naval Research Laboratory, Washington, DC 20375, USA; E-Mail: jill.dahlburg@nrl.navy.mil
² Swarthmore College, Swarthmore, PA 19081, USA
³ General Atomics, San Diego, CA 92186, USA
⁴ Massachusetts Institute of Technology, Cambridge, MA 02139, USA
⁵ University of Wisconsin, Madison, WI 53706, USA
⁶ University of California, Berkeley, CA 94720, USA
Abstract: Recent advances in space-based heliospheric observations, laboratory experimentation, and plasma simulation codes are creating an exciting new cross-disciplinary opportunity for understanding fast energy release and transport mechanisms in heliophysics and laboratory plasma dynamics, which had not been previously accessible. This article provides an overview of new observational, experimental, and computational assets, and describes current and near-term activities towards exploitation of synergies. Heliospheric observations reviewed include (1) the Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) on the NASA Solar Terrestrial Relations Observatory (STEREO) mission, the first instrument to provide remote sensing imagery observations with spatial continuity extending from the Sun to the Earth and (2) the Extreme-ultraviolet Imaging Spectrometer (EIS) on the Japanese Hinode spacecraft, which is measuring spectroscopically physical parameters of the solar atmosphere towards obtaining plasmas temperatures, densities, and mass motions. Near-term future missions such as the Solar Dynamics Observatory (SDO) and the Solar Orbiter with the Heliospheric Imager (SoloHI) on-board will also be discussed. Laboratory plasma experiments surveyed include the line-tied magnetic reconnection experiments at U. Wisconsin (relevant to coronal heating magnetic flux tube observations and simulations), and a future dynamo facility there; the Space Plasma Simulation Chamber at NRL that currently produces plasmas scalable to ionospheric and magnetospheric conditions and in the future also will be suited to study the physics of the solar corona; the MIT Versatile Toroidal Facility that provides direct experimental observation of reconnection dynamics; and the Swarthmore Spheromak Experiment, which provides well-diagnosed data on three-dimensional (3D) null-point magnetic reconnection that is also applicable to solar active regions embedded in pre-existing coronal fields. New computer capabilities highlighted include: HYPERION, a fully compressible 3D magnetohydrodynamics (MHD) code with radiation transport and thermal conduction; ORBIT-RF, a 4D Monte-Carlo code for the study of wave interactions with fast ions embedded in background MHD plasmas; the 3D implicit multi-fluid MHD spectral element code, HiFi; and the 3D Hall MHD code VooDoo. Research synergies that are being investigated with these new tools are primarily in the areas of particle acceleration, wave propagation, plasma instabilities and turbulence, magnetic reconnection, and plasma atomic processes.

Type of Paper: Article
Title: Recovery of Deuterium From H-D Gas Mixture by Thermal Diffusion in Branch Columns for Improved Performance
Author: Ho-Ming Yeh
Affiliation: Energy and Opto-Electronic Materials Research Center, Department of Chemical and Materials Engineering, Tamkang University,
Tamsui, Taipei county, Taiwan; E-Mail: hmyeh@mail.tku.edu.tw
Abstract: The thermogravitational thermal diffusion column introduced by Clusius and Dickel is a powerful device for the separation of isotope mixtures. For separation of hydrogen isotopes, this method is particularly attractive because of the large ratio in molecular weights. The estimations of deuterium recovery form H-D gas mixture by thermal diffusion have been done in the previous works for batch and continuous operations, as well as for transverse sampling stream operations. It was reported in previous works that the convective currents in the thermal diffusion column have two conflicting effects: a desirable cascading effect and an undesirable remixing effect. It therefore appears that proper control of the convective strength might effectively suppress the undesirable remixing effect while still preserving the desirable cascading effect, thereby leading to improved separation. In present study we found that the remixing effect due to the forced convection currents in a continuous-flow thermal diffusion column for enrichment of deuterium from H-D gas mixture can be reduced by employing the device of branch columns, instead of the device of single column, with the same total column length. The improvement in separation increases when the flow rate or the total column length increases, and can reach about 200%, based on that obtained in the single-column device.