19 research outputs found
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FRC formation and trapping by counter injection for MTF liner implosions
A new simplified design is being developed for injecting and trapping Field-Reversed Configurations (FRCs) into liners, which is compatible with the energetic liner implosions of interest for Magnetized Target Fusion (MTF). Conical theta pinches that inject from each end of the liner region are proposed. The conical angle can be chosen to make axial translation out of the conical theta pinch into the liner region occur on approximately the same time scale as radial compression. Thus no crowbar switch is needed for the high-voltage fast-rising current pulse. The toroidal field from conical theta-pinch injection and/or Z-pinch preionization should rapidly annihilate upon merging of the two oppositely directed FRCs. Two dc coils in a Helmholtz-like configuration are all that are needed to serve the functions of cusp, translation, and mirror fields for trapping in the liner. The mirror strength required for trapping is not as critical as when using onesided injection because the merging FRCs have no net momentum when they collide. Previously observed damping of axial kinetic energy suggests that viscous damping parallel to B 'is strong for FRCs with mfp comparable to FRC length, and conversion of directed energy to thermal energy should occur on a time scale comparable to the injection time. The electrical/mechanical details will be described, accompanied by numerical simulations of FRC formation using the MACH2 numerical code
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Scaling laws for FRC formation and prediction of FRX-C parameters
A semi-emperical method has been developed to extrapolate the experimental results from FRX-B, a field-reversed theta pinch which generates an FRC (Field-Reversed Configuration - a compact toroid with no toroidal field), to the larger size FRX-C. Even though there are many uncertainties about details of the dynamic processes by which an FRC is formed, the scaling exercise has proven useful in identifying limitations in the original FRX-C design and the design has been modified to have a lower voltage and larger capacitance. The goal of FRX-C remains unchanged: to test the confinement scaning of an FRC in a larger device over a wider range of temperatures. Of particular interest is the testing of possible MHD stability limits as the ratio of plasma size to gyro radius increases
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Final Report: Radiation-magnetohydrodynamic evolution and instability of conductors driven by megagauss magnetic fields
We are pleased to report important progress in experimentally characterizing and numerically modeling the transformation into plasma of walls subjected to pulsed megagauss magnetic fields. Understanding this is important to Magnetized Target Fusion (MTF) because an important limitation to the metal liner approach to MTF comes from the strong eddy current heating on the surface of the metal liner. This has intriguing non-linear aspects when the magnetic field is in the megagauss regime as needed for MTF, and may limit the magnetic field in an MTF implosion. Many faculty, students, and staff have contributed to this work, and, implicitly or explicitly, to this report. Contributors include, in addition to the PIs, Andrey Esaulov, Stephan Fuelling, Irvin Lindemuth, Volodymyr Makhin, Ioana Paraschiv, Milena Angelova, Tom Awe, Tasha Goodrich, Arunkumar Prasadam, Andrew Oxner, Bruno Le Galloudec, Radu Presura, and Vladimir Ivanov. Highlights of the progress made during the grant include: • 12 articles published, and 44 conference and workshop presentations made, on a broad range of issues related to this project; • An ongoing experiment that uses the 1 MA, 100-ns Zebra z-pinch at UNR to apply 2 5 megagauss to a variety of metal surfaces, examining plasma formation and evolution; • Numerical simulation studies of the 1-MA Zebra, and potential Shiva Star and Atlas experiments that include realistic equations of state and radiation effects, using a variety of tables. • Collaboration with other groups doing simulations of this experiment at LANL, VNIIEF, SNL, and NumerEx leading to a successful international workshop at UNR in the spring of 2008
The fundamental parameter space of controlled thermonuclear fusion”,
We apply a few simple first-principles equations to identify the parameter space in which controlled fusion might be possible. Fundamental physical parameters such as minimum size, energy, and power as well as cost are estimated. We explain why the fusion fuel density in inertial confinement fusion is more than 10 11 times larger than the fuel density in magnetic confinement fusion. We introduce magnetized target fusion as one possible way of accessing a density regime that is intermediate between the two extremes of inertial confinement fusion and magnetic confinement fusion and is potentially lower cost than either of these two
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Progress on the FRX-L FRC plasma injector at LANL for magnetized target fusion
The FRX-L Field Reversed Configuration plasma is now operational at Los Alamos National Laboratory. The goal of the project is to demonstrate the production of suitable FRC target plasmas for later MTF (Magnetized Target Fusion) implosion experiments which will first be carried out at the Air Force Research Laboratory in Albuquerque, New Mexico, in a few years' time. Expected plasma parameters in the 4 cm diameter, 30 cm long FRC are ne{approx}1017 cm-3, T{approx}100-300 eV, at 4-5 Tesla fields, with a lifetime of {approx}20 microseconds. The system includes a 0.5 T bias field, 70 kV 250 kHz ringing pre-ionization, and a 1.5 MA, 200 kJ main-theta coil bank. Maxwell rail gap plasma switches are used to start the PI bank, the main theta coil bank, and to crowbar the main bank. Initial results using the first diagnostic set of excluded flux loops, B-dot probes, visible light diodes, a fiber-optically coupled gated intensified visible spectrometer, and a 3.3 micron quadrature interferometer are presented. Future diagnostics include end-on bolometry, Thomson scattering, and a multi-chord fanned HeNe side-on interferometer. Multi-turn cusp and guide coils will be added later this year, to enable translation experiments into a cylindrical metal liner
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High-density FRC formation studies on FRX-L.
FRX-L (Field Reversed configuration experiment - Liner) is a magnetized-target injector for magnetized target fusion (MTF) experiments. It was designed with the goal of producing high-density n-1017 cm3 field reversed configurations (FRCs) and translating them into an aluminum liner (1-mm thick, 10-cm diameter cylindrical shell) for further compression to fusion conditions. Although operation at these high densities leads to shorter FRC lifetimes, our application requires thlat the plasma live only long enough to be translated and compressed, or on the order of 10-20 ps. Careful study of FRC formation in situ will be done in the present experiment to differentiate between effects introduced in future experiments by translation, trapping, and compression of the FRC. We present current results on the optimization of the FRC formation process on RX-L and compare the results with those from past experiments