James P. Blanchard

Overview of the ARIES-RS reversed-shear tokamak power plant study

The ARIES-RS tokamak is a conceptual, D‐T-burning 1000 MWe power plant. As with earlier ARIES design studies, the final design of ARIES-RS was obtained in a self-consistent manner using the best available physics and engineering models. Detailed analyses of individual systems together with system interfaces and interactions were incorporated into the ARIES systems code in order to assure self-consistency and to optimize towards the lowest cost system. The ARIES-RS design operates with a reversed-shear plasma and employs a moderate aspect ratio (A4.0). The plasma current is relatively low (Ip11.32 MA) and bootstrap current fraction is high ( fBC 0.88). Consequently, the auxiliary power required for RF current drive is relatively low ( 80 MW). At the same time, the average

Self-reciprocating radioisotope-powered cantilever

A reciprocating cantilever utilizing emitted charges from a millicurie radioisotope thin film is presented. The actuator realizes a direct collected-charge-to-motion conversion. The reciprocation is obtained by self-timed contact between the cantilever and the radioisotope source. A static model balancing the electrostatic and mechanical forces from an equivalent circuit leads to an analytical solution useful for device characterization. Measured reciprocating periods agree with predicted values from the analytical model. A scaling analysis shows that microscale arrays of such cantilevers provide an integrated sensor and actuator platform.

An elastic-plastic indentation model and its solutions

An analytical model of hardness has been developed. Four major indentation tests, namely indentation by cones, wedges, spheres, and flat-ended, axisymmetric cylinders have been analyzed based on the model. Analytical relationships among hardness, yield stress, elastic modulus, Poissons ratio, and indenter geometries have been found. These results enable hardness to be calculated in terms of uniaxial material properties and indenter geometries for a wide variety of elastic and plastic materials. These relationships can also be used for evaluating other mechanical properties through hardness measurements and for converting hardness from one type of hardness test into those of a different test. Comparison with experimental data and numerical calculations is excellent.

Structure and wear properties of carbon implanted 304 stainless steel using plasma source ion implantation

Abstract Methane plasma source ion implantation was used to implant carbon ions into 304 stainless steel. This paper examines the effects of high voltage pulse repetition rate on the structure and wear properties of implanted samples. The implantations were carried out at a target bias of -30 keV to a dose of 3 × 10 17 atoms cm -2 . Three repetition rates (42 Hz, 87 Hz and 126 Hz) were used. At low repetition rate, a carbon coated-implanted surface forms, which only an implanted surface is produced at high repetition rates. Metastable phases were observed and identified, and the microstructure at the surface was observed to be dependent on the chosen implantation parameters. Fe 2 C formed in the implantation layer which is produced at 42 Hz. Smaller size Fe 2 C and other forms of carbides (possibly Fe 3 C and/or (Cr, Fe) 7 C 3 ) formed in samples implanted at 87 Hz. An increase in repetition rate to 126 Hz produced a shallower amorphous implantation layer. Possible explanations of phase formation mechanisms are given. Wear resistance of all the implanted samples was improved, with the coated-implanted sample produced at 42 Hz showing the greatest improvement. The mechanism of wear was observed to change from an adhesive mode to a mild abrasive mode after implantation.

The Science and Technologies for Fusion Energy With Lasers and Direct-Drive Targets

We are carrying out a multidisciplinary multi-institutional program to develop the scientific and technical basis for inertial fusion energy (IFE) based on laser drivers and direct-drive targets. The key components are developed as an integrated system, linking the science, technology, and final application of a 1000-MWe pure-fusion power plant. The science and technologies developed here are flexible enough to be applied to other size systems. The scientific justification for this work is a family of target designs (simulations) that show that direct drive has the potential to provide the high gains needed for a pure-fusion power plant. Two competing lasers are under development: the diode-pumped solid-state laser (DPPSL) and the electron-beam-pumped krypton fluoride (KrF) gas laser. This paper will present the current state of the art in the target designs and lasers, as well as the other IFE technologies required for energy, including final optics (grazing incidence and dielectrics), chambers, and target fabrication, injection, and tracking technologies. All of these are applicable to both laser systems and to other laser IFE-based concepts. However, in some of the higher performance target designs, the DPPSL will require more energy to reach the same yield as with the KrF laser.

Apollo - An advanced fuel fusion power reactor for the 21st century

A preconceptual design of a tokamak reactor fueled by a D-He-3 plasma is presented. A low aspect ratio (A=2-4) device is studied here but high aspect ratio devices (A > 6) may also be quite attractive. The Apollo D-He-3 tokamak capitalizes on recent advances in high field magnets (20 T) and utilizes rectennas to convert the synchrotron radiation directly to electricity. The overall efficiency ranges from 37 to 52% depending on whether the bremsstrahlung energy is utilized. The low neutron wall loading (0.1 MW/m/sup 2/) allows a permanent first wall to be designed and the low nuclear decay heat enables the reactor to be classed as inherently safe. The cost of electricity from Apollo is > 40% lower than electricity from a similar sized DT reactor.

The Fusion Nuclear Science Facility, the Critical Step in the Pathway to Fusion Energy

The proposed Fusion Nuclear Science Facility (FNSF) represents the first facility to enter the complex fusion nuclear regime, and its technical mission and attributes are being developed. The FNSF represents one part of the fusion energy development pathway to the first commercial power plant with other major components being the pre-FNSF research and development, research in parallel with the FNSF, pre-DEMO research and development, and the demonstration power plant (DEMO). The Fusion Energy Systems Studies group is developing the technical basis for the FNSF in order to provide a better understanding of the demands on the fusion plasma and fusion nuclear science programs.

The ARIES Advanced and Conservative Tokamak Power Plant Study

Abstract Tokamak power plants are studied with advanced and conservative design philosophies to identify the impacts on the resulting designs and to provide guidance to critical research needs. Incorporating updated physics understanding and using more sophisticated engineering and physics analysis, the tokamak configurations have developed a more credible basis compared with older studies. The advanced configuration assumes a self-cooled lead lithium blanket concept with SiC composite structural material with 58% thermal conversion efficiency. This plasma has a major radius of 6.25 m, a toroidal field of 6.0 T, a q95 of 4.5,a βtotal N of 5.75, an H98 of 1.65, an n/nGr of 1.0, and a peak divertor heat flux of 13.7 MW/m2. The conservative configuration assumes a dual-coolant lead lithium blanket concept with reduced-activation ferritic martensitic steel structural material and helium coolant, achieving a thermal conversion efficiency of 45%. The plasma has a major radius of 9.75 m, a toroidal field of 8.75 T, a q95 of 8.0, a βtotal N of 2.5, an H98 of 1.25, an n/nGr of 1.3, and a peak divertor heat flux of 10 MW/m2. The divertor heat flux treatment with a narrow power scrape-off width has driven the plasmas to larger major radius. Edge and divertor plasma simulations are targeting a basis for high radiated power fraction in the divertor, which is necessary for solutions to keep the peak heat flux in the range 10 to 15 MW/m2. Combinations of the advanced and conservative approaches show intermediate sizes. A new systems code using a database approach has been used and shows that the operating point is really an operating zone with some range of plasma and engineering parameters and very similar costs of electricity. Other papers in this issue provide more detailed discussion of the work summarized here.

The ARIES-RS power core—recent development in Li/V designs

The ARIES-RS fusion power plant design study is based on reversed-shear (RS) physics with a Li/V (lithium breeder and vanadium structure) blanket. The reversed-shear discharge has been documented in many large tokamak experiments. The plasma in the RS mode has a high beta, low current, and low current drive requirement. Therefore, it is an attractive physics regime for a fusion power plant. The blanket system based on Li/V has high temperature operating capability, good tritium breeding, excellent high heat flux removal capability, long structural life time, low activation, low after heat and good safety characteristics. For these reasons, the ARIES-RS reactor study selected Li/V as the reference blanket. The combination of attractive physics and attractive blanket engineering is expected to result in a superior power plant design. This paper summarizes the power core design of the ARIES-RS power plant study.

The ARIES tokamak fusion reactor study

The Advanced Reactor Innovation and Evaluation Study (ARIES) is a community effort to develop several visions of the tokamak as a fusion power reactor. The aims are to determine its potential economics, safety, and environmental features and to identify physics and technology areas with the highest leverage for achieving the best tokamak reactor. The authors focus on the ARIES-1 design. Parametric systems studies show that the optimum first stability tokamak has relatively low plasma current ( approximately 12 MA), high plasma aspect ratio ( approximately 4-6), and high magnetic field ( approximately 24 T at the coil). ARIES-I is a 1000-MWe (net) reactor with a plasma major radius of 6.5 m, a minor radius of 1.4 m, a neutron wall loading of about 2.8 MW/m/sup 2/, and a mass power density of about 90 kWe/tonne. The ARIES-I reactor operates at steady state using ICRF (ion-cyclotron range of frequency) fast waves to drive current in the plasma core and lower-hybrid waves for edge-plasma current drive. The ARIES-I blanket is cooled by He and consists of SiC-composite structural material, Li/sub 4/SiO/sub 4/ solid breeder, and Be neutron multiplier, all chosen for their low-activation and low-decay after-heat in order to enhance the safety and environmental features of the design. The ARIES-I design has a competitive cost of electricity and superior safety and environmental features.<<ETX>>