Structural effects of major plasma disruptions on tokamak fusion reactors

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1984.MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE.Includes bibliographical references.by Mark Steven Tillack.Ph.D

IFE Final Optics and Chamber Dynamics Modeling and Experiments Final Technical Report

Our OFES-sponsored research on IFE technology originally focused on studies of grazing-incidence metal mirrors (GIMM's). After the addition of GIMM research to the High Average Power Laser (HAPL) program, our OFES-sponsored research evolved to include laser propagation studies, surface material evolution in IFE wetted-wall chambers, and magnetic intervention. In 2003, the OFES IFE Technology program was terminated. We continued to expend resources on a no-cost extension in order to complete student research projects in an orderly way and to help us explore new research directions. Those explorations led to funding in the field of extreme ultraviolet lithography, which shares many issues in common with inertial fusion chambers, and the field of radiative properties of laser-produced plasma

R A P I D C O M M U N I C AT I O N Nonclassical hydrodynamic behavior of Sn plasma irradiated with a long duration CO 2 laser pulse

Abstract It was found that the electron density scale length of Sn plasma irradiated with a long duration CO 2 laser pulse is much shorter than that predicted by the classical isothermal model. The experimentally observed small dominant region of in-band (2% bandwidth) 13.5-nm extreme ultraviolet (EUV) emission coincides with this constrained hydrodynamic behavior. The lower hydrodynamic efficiency may come from the strongly inhibited ablation mass and makes a CO 2 -laser-produced Sn plasma suitable as an EUV radiation source. When an intense laser pulse arrives at the surface of a solid material placed in a vacuum, a thin layer of the material is ablated, heated, and expands into vacuum due to the thermal gradient. Such hydrodynamic expansion of a laser-produced plasma has been studied for more than 40 years motivated by a wide range of applications, such as efficient compression of a pellet in laser fusion, X-ray lasers, laser ion acceleration, and short wavelength radiation sources For the application of laser fusion, a lot of effort has been expended to enhance hydrodynamic efficiency in order to achieve efficient compression of the fusion pellet. It has been shown that short wavelength lasers could provide higher hydrodynamic efficiency as compared with long wavelength lasers Experiments are carried out using a home-built master oscillator and power amplifier (MOPA) CO 2 laser system as the pumping laser puls

R A P I D C O M M U N I C AT I O N Nonclassical hydrodynamic behavior of Sn plasma irradiated with a long duration CO 2 laser pulse

Abstract It was found that the electron density scale length of Sn plasma irradiated with a long duration CO 2 laser pulse is much shorter than that predicted by the classical isothermal model. The experimentally observed small dominant region of in-band (2% bandwidth) 13.5-nm extreme ultraviolet (EUV) emission coincides with this constrained hydrodynamic behavior. The lower hydrodynamic efficiency may come from the strongly inhibited ablation mass and makes a CO 2 -laser-produced Sn plasma suitable as an EUV radiation source. When an intense laser pulse arrives at the surface of a solid material placed in a vacuum, a thin layer of the material is ablated, heated, and expands into vacuum due to the thermal gradient. Such hydrodynamic expansion of a laser-produced plasma has been studied for more than 40 years motivated by a wide range of applications, such as efficient compression of a pellet in laser fusion, X-ray lasers, laser ion acceleration, and short wavelength radiation sources For the application of laser fusion, a lot of effort has been expended to enhance hydrodynamic efficiency in order to achieve efficient compression of the fusion pellet. It has been shown that short wavelength lasers could provide higher hydrodynamic efficiency as compared with long wavelength lasers Experiments are carried out using a home-built master oscillator and power amplifier (MOPA) CO 2 laser system as the pumping laser puls

Hierarchically organized nanostructured TiO2 for photocatalysis applications

A template-free process for the synthesis of nanocrystalline TiO2 hierarchical microstructures by reactive Pulsed Laser Deposition (PLD) is here presented. By a proper choice of deposition parameters a fine control over the morphology of TiO2 microstructures is demonstrated, going from classical compact/columnar films to a dense forest of distinct hierarchical assemblies of ultrafine nanoparticles (<10 nm), up to a more disordered, aerogel-type structure. Correspondingly, film density varies with respect to bulk TiO2 anatase, with a degree of porosity going from 48% to over 90%. These structures are stable with respect to heat treatment at 400 centigrade degrees, which results in crystalline ordering but not in morphological changes down to the nanoscale. Both as deposited and annealed films exhibit very promising photocatalytic properties, even superior to standard Degussa P25 powder, as demonstrated by the degradation of stearic acid as a model molecule. The observed kinetics are correlated to the peculiar morphology of the PLD grown material. We show that the 3D multi-scale hierarchical morphology enhances reaction kinetics and creates an ideal environment for mass transport and photon absorption, maximizing the surface area-to-volume ratio while at the same time providing readily accessible porosity through the large inter-tree spaces that act as distributing channels. The reported strategy provides a versatile technique to fabricate high aspect ratio 3D titania microstuctures through a hierarchical assembly of ultrafine nanoparticles. Beyond photocatalytic and catalytic applications, this kind of material could be of interest for those applications where high surface-to-volume and efficient mass transport are required at the same time.Comment: 10 pages, 7 figures, Nanotechnology (accepted

Engineering Options for the U.S. Fusion Demo

Through its successful operation, the US Fusion Demo must be sufficiently convincing that a utility or independent power producer will choose to purchase one as its next electric generating plant. A fusion power plant which is limited to the use of currently-proven technologies is unlikely to be sufficient attractive to a utility unless fuel shortages and regulatory restrictions are far more crippling to competing energy sources than currently anticipated. In that case, the task of choosing an appropriate set of engineering technologies today involves trade-offs between attractiveness and technical risk. The design space for an attractive tokamak fusion power core is not unlimited; previous studies have shown that advanced low-activation ferritic steel, vanadium alloy, or SiC/SiC composites are the only candidates they have for the primary in-vessel structural material. An assessment of engineering design options has been performed using these three materials and the associated in-vessel component designs which are compatible with them

Engineering Options for the U.S. Fusion Demo *

ABSTRACT Through its successful operation, the U.S. Fusion Demo must be sufficiently convincing that a utility or independent power producer will choose to purchase one as its next electric generating plant. A fusion power plant which is limited to the use of currently-proven technologies is unlikely to be sufficiently attractive to a utility unless fuel shortages and regulatory restrictions are far more crippling to competing energy sources than currently anticipated. In that case, the task of choosing an appropriate set of engineering technologies today involves trade-offs between attractiveness and technical risk. The design space for an attractive tokamak fusion power core is not unlimited; previous studies have shown that advanced lowactivation ferritic steel, vanadium alloy, or SiC/SiC composites are the only candidates we have for the primary in-vessel structural material. An assessment of engineering design options has been performed using these three materials and the associated in-vessel component designs which are compatible with them

Progress and Critical Issues for IFE Blanket and Chamber Research

Advances in high gain target designs for Inertial Fusion Energy (IFE), and the initiation of construction of large megajoule-class laser facilities in the U.S. (National Ignition Facility) and France (Laser-Megajoule) capable of testing the requirements for inertial fusion ignition and propagating burn, have improved the prospects for IFE. Accordingly, there have recently been modest increases in the US fusion research program related to the feasibility of IFE. These research areas include heavy-ion accelerators, Krypton-Fluoride (KrF) gas lasers, diode-pumped, solid-state (DPSSL) lasers, IFE target designs for higher gains, feasibility of low cost IFE target fabrication and accurate injection, and long-lasting IFE fusion chambers and final optics. Since several studies of conceptual IFE power plant and driver designs were completed in 1992-1996 [1-5], U.S. research in the IFE blanket, chamber, and target technology areas has focused on the critical issues relating to the feasibility of IFE concepts towards the goal of achieving economically-competitive and environmentally-attractive fusion energy. This paper discusses the critical issues in these areas, and the approaches taken to address these issues. The U.S. research in these areas, called IFE Chamber and Target Technologies, is coordinated through the Virtual Laboratory for Technology (VLT) formed by the Department of Energy in December 1998