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[en] Recent advances in energy storage, switching and magnet technology make alectromagnetic acceleration a viable alternative to chemical propulsion for certain tasks, and a means to perform other tasks not previously feasible. Launchers of interest include the dc railgun driven by energy stored inertially in a homopolar generator and transferred through a switching inductor, and the opposite extreme, the synchronous mass driver energized by a high voltage alternator through an oscillating coil-capacitor circuit. A number of hybrid variants between these two extremes are also promising. A novel system described here is the momentum transformer which transfers momentum from a massive chemically driven armature to a much lighter, higher velocity projectile by magnetic flux compression. Potential applications include the acceleration of gram-size particles for hypervelocity research and for use as reaction engines in space transport; high velocity artillery; stretcher-size tactical supply and medical evaluation vehicles; the launching of space cargo or nuclear waste in one-ton packets using off-peak electric power
[en] A success oriented research and development plan for Inertial Confinement Fusion (ICF) leading to a commercial demonstration reactor by the year 2010 has been generated. The RandD plan was developed by using the unique approach of combining an ICF-experienced project team with technical forecast information obtained through interviews with experts in ICF-relevant technologies. The technical forecast data were analyzed with a logic network formalism to determine preferred RandD options to reach the aggressive 2010 goal. The application of the developed technical forecasting techniques has proved to be a useful planning tool
[en] The 3rd EFPW was convened in December 1995 at Segovia, with the support of Eurotom and CIEMAT. The established pattern for these meetings was followed, beginning with a range of topical themes of interest to the magnetic confinement fusion research community. Subsequent presentations moved on to summarize progress in experiments on JET and the design activity for ITER. The topical theme this year comprised tokamak operational limits, disruption phenomena and transport issues (including the role of plasma edge effects, dimensionless scaling analysers and 'non-local' dependences). Also discussed were tokamak concept improvements, with additional contributions emphasizing the synergistic role of stellarators. JET highlights reported were the achievements of the experiments with the Mk1 divertor, high fusion performance plasmas, and exploratory work on discharge optimization techniques (such as reversed magnetic shear). This article summarizes the proceedings of the workshop on the topical themes and the JET results, including a number of points raised in the associated discussion sessions. (author)
[en] Recent Magnetized Liner Inertial Fusion experiments at the Sandia National Laboratories Z pulsed power facility have featured a PDV (Photonic Doppler Velocimetry) diagnostic in the final power feed section for measuring load current. In this paper, we report on an anomalous pressure that is detected on this PDV diagnostic very early in time during the current ramp. Early time load currents that are greater than both B-dot upstream current measurements and existing Z machine circuit models by at least 1 MA would be necessary to describe the measured early time velocity of the PDV flyer. This leads us to infer that the pressure producing the early time PDV flyer motion cannot be attributed to the magnetic pressure of the load current but rather to an anomalous pressure. Using the MHD code ALEGRA, we are able to compute a time-dependent anomalous pressure function, which when added to the magnetic pressure of the load current, yields simulated flyer velocities that are in excellent agreement with the PDV measurement. As a result, we also provide plausible explanations for what could be the origin of the anomalous pressure.
[en] The first indirect-drive hohlraum experiments at the National Ignition Facility have demonstrated symmetric capsule implosions at unprecedented laser drive energies of 0.7 MJ. 192 simultaneously fired laser beams heat ignition hohlraums to radiation temperatures of 3.3 million Kelvin compressing 1.8-millimeter capsules by the soft x rays produced by the hohlraum. Self-generated plasma-optics gratings on either end of the hohlraum tune the laser power distribution in the hohlraum producing symmetric x-ray drive as inferred from capsule self-emission measurements. These experiments indicate conditions suitable for compressing deuterium-tritium filled capsules with the goal to achieve burning fusion plasmas and energy gain in the laboratory.
[en] Of the United States' two major research and development programs pursuing the goal of fusion energy production, the magnetic confinement fusion energy (MFE) program was removed from security classification restrictions in 1958, whereas the inertial confinement fusion (ICF) program remains classified in part, with concomitant barriers to information flow and scientific cooperation both internationally and intranationally. This report attempts to put the question of ICF classification in perspective, and to review and remark upon especially to an appeal by Ray Kidder for ICF declassification. 16 refs
[en] A self-consistent model of the L to H transition is derived from coupled nonlinear envelope equations for the fluctuation level, radial electric field shear, Er' and pressure gradient, triangledown Pi. These equations exhibit a bifurcation between dual L-mode and H-mode fixed points. They show that the L to H transition has similar characteristics to a phase transition of the second kind for which the order parameter is Er'. The transition occurs when the turbulence drive is large enough to overcome the damping of the E x B flow. This leads to a power threshold condition for the transition Pcrit ∼ (μnT)edge aRLs
[en] This paper presents a model of the divertor region. The model is based on the two-point approach described by Galambos and Peng but has been enhanced to include the key processes of remote radiative cooling, neutral recycling, particle convection, ash effects, and the effects of divertor geometry and plate material. Neutral particle effects are represented using a wedge-shaped section of plasma overlying the divertor plate and a slab attenuation model. The results of benchmarking against four other divertor models demonstrate the applicability of the proposed model. System sensitivities to key parameters are discussed and several general observations regarding divertor design are presented