Results 1 - 10 of 20183
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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] The problem of fast ion transport in inertially confined plasmas was studied using a variety of numerical techniques. Computer codes were developed which approached the problem with the aid of flux-limited, multi-group diffusion theory, particle tracking theory, and a combination of these two techniques which took advantage of the fact that they are most effective in different regions of the slowing ion energy spectrum. The problem of numerical diffusion in multi-group diffusion codes was examined with the aid of a modified code which substituted a continuous energy loss formula for the usual differencing in energy space. Results obtained using the three codes mentioned above were compared with a benchmark Monte Carlo calculation. The combined code results were found to be significantly closer to the Monte Carlo ideal than those of the individual particle tracking or multi-group diffusion codes. In order to demonstrate its flexibility, the combined code was used to model the progress of a thermonuclear burn wave in a compressed pellet of fuel material
[en] Equilibrium equations are derived for a plasma in an arbitrary inhomogeneous magnetic configuration and are solved for DRAKONS case. The second-order equilibrium beta limit for DRAKONS with triangular CRELs is discussed for longitudinally inhomogeneous magnetic field. Numerical calculations of the beta limit are made for a parabolic pressure profile and a given magnetic field distribution. It is shown that the beta limit with a longitudinally inhomogeneous magnetic field can be much higher than that with a homogeneous magnetic field, and affected to second-order largely by the ratio of the straight section length to the CREL length. (orig.)
[en] The general properties of Galatheas and ways of overcoming the difficulty associated with the creation of myxines are analyzed. Arguments are presented in favor of the advantages of these systems. 25 refs., 9 figs