38 research outputs found
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Interplanetary space transport using inertial fusion propulsion
In this paper, we indicate how the great advantages that ICF offers for interplanetary propulsion can be accomplished with the VISTA spacecraft concept. The performance of VISTA is expected to surpass that from other realistic technologies for Mars missions if the energy gain achievable for ICF targets is above several hundred. Based on the good performance expected from the U. S. National Ignition Facility (NIF), the requirements for VISTA should be well within the realm of possibility if creative target concepts such as the fast ignitor can be developed. We also indicate that a 6000-ton VISTA can visit any planet in the solar system and return to Earth in about 7 years or less without any significant physiological hazards to astronauts. In concept, VISTA provides such short-duration missions, especially to Mars, that the hazards from cosmic radiation and zero gravity can be reduced to insignificant levels. VISTA therefore represents a significant step forward for space-propulsion concepts
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System study of a diode-pumped solid-state-laser driver for inertial fusion energy
The present a conceptual design of a diode-pumped solid-state-laser (DPSSL) driver for an inertial fusion energy (IFE) power plant based on the maximized cost of electricity (COE) as determined in a comprehensive systems study. This study contained extensive detail for all significant DPSSL physics and costs, plus published scaling relationships for the costs of the target chamber and the balance of plant (BOP). Our DPSSL design offers low development cost because it is modular, can be fully tested functionally at reduced scale, and is based on mature solid-state-laser technology. Most of the parameter values that we used are being verified by experiments now in progress. Future experiments will address the few issues that remain. As a consequence, the economic and technical risk of our DPSSL driver concept is becoming rather low. Baseline performance at 1 GW{sub e} using a new gain medium [Yb{sup 3+}-doped Sr{sub 5}(PO{sub 4}){sub 3}F or Yb:S-FAP] includes a product of laser efficiency and target gain of {eta}G = 7, and a COE of 8.6 cents/kW{center_dot}h, although values of {eta}G {ge} 11 and COEs {le}6.6 cents/kW{center_dot}h are possible at double the assumed target gain of 76 at 3.7 MJ. We present a summary of our results, discuss why other more-common types of laser media do not perform as well as Yb:S-FAP, and present a simple model that shows where DPSSL development should proceed to reduce projected COEs
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Prospects for inertial fusion energy based on a diode-pumped solid-state laser (DPSSL) driver: Overview and development path
It is now known with certainty that the type of fusion known as inertial fusion will work with sufficient energy input, so inertial fusion is really beyond the ``scientific breakeven`` point in many respects. The most important question that remains for inertial fusion energy (IFE) is whether this type of fusion can operate with sufficiently low input energy to make it economically feasible for energy production. The constraint for low input energy demands operation near the inertial fusion ignition threshold, and such operation creates enormous challenges to discover a target design that will produce sufficient energy gain. There are also multiple issues relating to the scientific feasibility of using a laboratory-type ``driver`` to energize a target, such as those concerning bandwidth and beam smoothing for ``direct drive,`` and extension of hohlraum plasma physics to the IFE scale for ``indirect drive.`` One driver that appears as though it will be able to meet the IFE requirements, assuming modest development and sufficient target gain, is a diode-pumped solid-state laser (DPSSL). We give an overview of this type of laser system, and explain what development remains for the economic production of electricity using this type of driver for IFE
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Relative Advantages of Direct and Indirect Drive for an Inertial Fusion Energy Power Plant Driven by a Diode-Pumped Solid-State Laser
This paper reviews our current understanding of the relative advantages of direct drive (DD) and indirect drive (ID) for a 1 GWe inertial fusion energy (IFE) power plant driven by a diode-pumped solid-state laser (DPSSL). This comparison is motivated by a recent study (1) that shows that the projected cost of electricity (COE) for DD is actually about the same as that for ID even though the target gain for DD can be much larger. We can therefore no longer assume that DD is the ultimate targeting scenario for IFE, and must begin a more rigorous comparison of these two drive options. The comparison begun here shows that ID may actually end up being preferred, but the uncertainties are still rather large
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Improved understanding of first-mall vaporization-condensation in inertial confinement fusion reactors. Revision 1
We report approximate x-ray and debris spectra emanating from a region of compressed DT fuel representing the imploded configuration of a generic direct-drive ICF reactor pellet. We show how the spectra are modified by spherical lead shields of various thicknesses placed near the pellet, and show that it is not possible to lessen the ablation of the first wall or blanket of a low-pressure ICF reactor chamber through use of such shields. Then we report that the calculated x-ray spectra alone (i.e., without the associated debris) cause vaporization of a first wall placed at a radius of 4 m that is much more than previously expected. This result increases the importance of understanding the details of the vaporization and condensation phenomena
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MEASUREMENT OF THE POSITRON-ELECTRON RATIO IN THE PRIMARY COSMIC RAYS FROM 5 TO 50 GeV
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MEASUREMENT OF THE POSITRON-ELECTRON RATIO IN THE PRIMARY COSMIC RAYS FROM 5 TO 50 GeV
Failure Distribution Analysis of a Novel Subsea Valve Actuator Concept based on Reliability Database
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Analysis of dense pusher laser-driven implosions for intermediate densities
Post-shot analysis of targets designed to achieve a diagnosible compression of DT gas to 2. g/cm/sup 3/ or 10 x liquid density is reported. The SHIVA laser provided 15 to 20 TW of 1.06 ..mu..m laser light. Detailed comparisons of diagnostic results with hydro-code calculations are made. Implications for laser light absorption/scattering, thermal conduction, suprathermal electron preheat, implosion symmetry, and pusher-fuel mix are discussed. Uncertainties of the density determination methods are analyzed. Good overall consistency is found, indicating strong support for the successful attainment of 1.-3. g/cm/sup 3/
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Transport vehicle for manned Mars missions powered by inertial confinement fusion
Inertial confinement fusion (ICF) is an ideal engine power source for manned spacecraft to Mars because of its inherently high power-to-mass ratios and high specific impulses. We have produced a concept for a vehicle powered by ICF and utilizing a magnetic thrust chamber to avoid plasma thermalization with wall structures and the resultant degradation of specific impulse that are unavoidable with the use of mechanical thrust chambers. This vehicle is capable of 100-day manned Mars missions with a 100-metric-ton payload and a total vehicle launch mass near 6000 metric tons, based on advanced technology assumed to be available by A.D. 2020. Such short-duration missions minimize radiation exposures and physiological deterioration of astronauts