ARC: A compact, high-field, fusion nuclear science facility and demonstration power plant with demountable magnets

The affordable, robust, compact (ARC) reactor is the product of a conceptual design study aimed at reducing the size, cost, and complexity of a combined fusion nuclear science facility (FNSF) and demonstration fusion Pilot power plant. ARC is a ∼200–250 MWe tokamak reactor with a major radius of 3.3 m, a minor radius of 1.1 m, and an on-axis magnetic field of 9.2 T. ARC has rare earth barium copper oxide (REBCO) superconducting toroidal field coils, which have joints to enable disassembly. This allows the vacuum vessel to be replaced quickly, mitigating first wall survivability concerns, and permits a single device to test many vacuum vessel designs and divertor materials. The design point has a plasma fusion gain of Q[subscript p] ≈ 13.6, yet is fully non-inductive, with a modest bootstrap fraction of only ∼63%. Thus ARC offers a high power gain with relatively large external control of the current profile. This highly attractive combination is enabled by the ∼23 T peak field on coil achievable with newly available REBCO superconductor technology. External current drive is provided by two innovative inboard RF launchers using 25 MW of lower hybrid and 13.6 MW of ion cyclotron fast wave power. The resulting efficient current drive provides a robust, steady state core plasma far from disruptive limits. ARC uses an all-liquid blanket, consisting of low pressure, slowly flowing fluorine lithium beryllium (FLiBe) molten salt. The liquid blanket is low-risk technology and provides effective neutron moderation and shielding, excellent heat removal, and a tritium breeding ratio ≥ 1.1. The large temperature range over which FLiBe is liquid permits an output blanket temperature of 900 K, single phase fluid cooling, and a high efficiency helium Brayton cycle, which allows for net electricity generation when operating ARC as a Pilot power plant.United States. Department of Energy (Grant DE-FG02-94ER54235)United States. Department of Energy (Grant DE-SC008435)United States. Department of Energy. Office of Fusion Energy Sciences (Grant DE-FC02-93ER54186)National Science Foundation (U.S.) (Grant 1122374

Financing Public Elementary and Secondary Schools in Nebraska

Nebraska\u27s system for funding public schools is deteriorating. Shifts in population, variations in tax capacity, and changes in the mission defined for public schools make the current system inadequate and inequitable. Funding problems are compounded by the large number of school districts which divide human and financial resources in the state unequally. Problems in the finance system are described, and suggestions for determining the minimum education program to be funded, the most cost-effective organization of school districts, measures for fair acquisition of funds, and procedures for equitable allocation of state aid to public schools are discussed

2-Color interferometry as a fluctuation diagnostic on Alcator C-Mod

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2013.Cataloged from PDF version of thesis.Includes bibliographical references (pages 139-147).The two-color interferometer diagnostic on Alcator C-Mod has been upgraded to measure line-integrated electron density fluctuations for turbulence and transport studies. Heterodyne signals from ten vertical-viewing CO2 laser chords are demodulated relative to a local oscillator using high bandwidth analog in-phase/quadrature electronics, replacing lower bandwidth digital fringe counting electronics. The raw outputs of the high bandwidth electronics, which are proportional to the sine and cosine of the interferometric phase shift, are digitized at up to 10 MHz, which is sufficient for fluctuation analysis. Extraction of the measured phase from the sine and cosine signals is now performed entirely in software, providing the line-integrated electron density at high bandwidth. The interferometer design, calibration, and measurement uncertainty is presented. Measurement uncertainties due to nonlinearities in the analog electronics are found to be comparable to the uncertainties of the previous system. The interferometer can now resolve line-integrated electron density fluctuations with major-radial wavenumbers below ... . The new fluctuation measurement capability is used to partially verify the calibration and low-kR wavenumber response of phase-contrast imaging, to aid in gyrokinetic transport model validation research. Agreement between the two diagnostics is demonstrated for broadband fluctuations and the low-kR component of the quasi-coherent mode, improving confidence in the calibration of the phase-contrast imaging system. Both diagnostics observe a series of fluctuations during quasi-steady periods of minority heated I-mode plasmas with strong off-axis electron heating. The observed fluctuations are localized to the plasma core using Doppler shift analysis and data from edge fluctuation diagnostics. Transport analysis shows that the fluctuations do not correlate with enhanced thermal transport, and gyrokinetic linear stability analysis shows that the plasma is stable to drift wave turbulence, ruling out the possibility that the observed fluctuations are destabilized drift wave turbulence.by Cale Phillip Kasten.S.M