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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,171 records · Page 65

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NASA NTRS1972

Design, testing, fabrication and launch support of a liquid chemical barium release payload (utilizing the liquid fluorine-barium salt/hydrazine system)

A payload was designed which included a cryogenic oxidizer tank, a fuel tank, and burner section. Release of 30 lb of chemicals was planned to occur in 2 seconds at the optimum oxidizer to fuel ratio. The chemicals consisted of 17 lb of liquid fluorine oxidizer and 13 lb of hydrazine-barium salt fuel mixture. The fuel mixture was 17% barium chloride, 16% barium nitrate, and 67% hydrazine, and contained 2.6 lb of available barium. Two significant problem areas were resolved during the program: explosive valve development and burner operation. The release payload was flight tested, from Wallops Island, Virginia. The release took place at an altitude of approximately 260 km. The release produced a luminous cloud which expanded very rapidly, disappearing to the human eye in about 20 seconds. Barium ion concentration slowly increased over a wide area of sky until measurements were discontinued at sunrise (about 30 minutes).

Stokes, C. S.↗

NASA NTRS1972

Public health applications of remote sensing

Remote infrared and multispectral photography were used to identify coastal salt water-fresh water interfaces conducive to encephalitis vector mosquito breeding in Florida, and to determine the environmental conditions that caused an explosive outbreak of anthrax in Louisiana. Multiband photographic inventories were obtained by simultaneously processing three photographic negatives of the same view which record different wavelength portions of the same light. The process enhances differentiation of vegetative communities and sharply delineates edge effects by assigning false colors to differentiate subtle density differences.

Fuller, C. E.↗

NASA NTRS1971

A study of an advanced confined linear energy source

A literature survey and a test program to develop and evaluate an advanced confined linear energy source were conducted. The advanced confined linear energy source is an explosive or pyrotechnic X-Cord (mild detonating fuse) supported inside a confining tube capable of being hermetically sealed and retaining all products of combustion. The energy released by initiation of the X-Cord is transmitted through the support material to the walls of the confining tube causing an appreciable change in cross sectional configuration and expansion of the tube. When located in an assembly that can accept and use the energy of the tube expansion, useful work is accomplished through fracture of a structure, movement of a load, reposition of a pin, release of a restraint, or similar action. The tube assembly imparts that energy without release of debris or gases from the device itself. This facet of the function is important to the protection of men or equipment located in close proximity to the system during the time of function.

Anderson, M. C.↗

NASA NTRS1972

On the acceleration of high-energy particles in solar flares

The relationship is discussed between some characteristics of microwave Type 4 radio bursts and solar cosmic ray protons of MeV energy. It is shown that the peak flux intensity of those bursts is almost linearly correlated with MeV proton peak flux observed by satellites near the earth and that protons and electrons would be accelerated simultaneously by a similar mechanism during the explosive phase of solar flares. Brief discussion is given on the propagation of solar cosmic rays in the solar envelope after ejection from the flare regions.

Sakurai, K.↗

NASA NTRS1971

Rocket propulsion by thermonuclear micro-bombs ignited with intense relativistic electron beams.

Discussion of a method for the ignition of a thermonuclear microbomb by means of an intense relativistic electron beam with regard to its potential application to rocket propulsion. With such a system, exhaust velocities up to 1000 km/sec, corresponding to a specific impulse of 100,000 sec, seem to be within the realm of possibility. The rocket is propelled by a chain of thermonuclear microbombs exploded in a concave magnetic mirror produced by superconducting field coils. The magnetic pressure of the field reflects the fireball generated by the explosion. For the large capacitor bank required to generate the intense relativistic electron beam, a desirable lightweight design may be possible through use of ferroelectric materials. Because of the high cost of the T-D and He 3-D thermonuclear material, the system has to be optimized by minimizing the T-D and He 3-D consumption by a proper TD and He 3-D fuel to hydrogen propellant mass ratio, leading to a larger total system mass than would be absolutely necessary.

Winterberg, F.↗

NASA NTRS1971

Postulation of the arc restrike mechanisms for exploding wires and tubes.

The many facets of exploding wire restrikes are studied. They are related to the cylindrical shock wave which pumps down the density of the center region of a line energy source or around the surface of the heated wire continuously to a lower density. When the density of any region is pumped down to lower than Paschen's electric breakdown criteria, restrike occurs. The cylindrical shocks occurring in exploding wires are, in general, divided into two types. In the first type the shock is generated by the wire explosion and in the second type the shock is generated by the heat conduction of the wire to the surrounding gas. Application of this mechanism to exploding tubes will enable us to create arc channels in arbitrary gaseous atmospheres with controllable plasma density with the contamination excluded. Neutral density shielded plasma experiments, therefore, can be conducted in a controllable environment.

Cheng, D. Y.↗

NASA NTRS1971

A note on the acceleration phase of high-energy particles in the solar flare on 7 July, 1966.

The acceleration phase of solar cosmic rays and relativistic electrons is studied on the basis of the observational data available on the optical, radio, X-ray, and particle events associated with the solar flare that occurred on July 7, 1966. The generating process of hydromagnetic shock waves which excited the type-II radio burst detected at a frequency below about 100 MHz is also discussed. The results of the study suggest that no secondary acceleration process after the explosive phase can contribute much to the generation of high energy particles. The ejection of solar cosmic rays and relativistic electrons seems to be related to the expansion of the magnetic bulge which can trap accelerated electrons from the triggering region of solar flares.

Sakurai, K.↗

NASA NTRS1972

Equations of motion of a constrained split fairing system during opening.

Description of a constrained split fairing technique for avoiding contamination of a sounding rocket's payload environment by an uncontained explosive actuation device. The development is presented of the equations of motion of the fairing halves during the opening sequence assumed to occur above the sensible atmosphere. It is believed that a significant insight into the general motion results from the solution obtained.

Saunders, R. C., Jr.↗

NASA NTRS1972

Laser-induced gas breakdown - Spectroscopic and chemical studies.

Discussion of the results of several experimental investigations on laser-induced gas breakdown. The experiments included time-resolved spectroscopy, direct detection of H atoms with a TiO2 probe, and chemical reactions; each of them provided insight into the behavior of the medium at different times. Chemical reactions and explosions have been initiated by the laser beam when a plasma was created. No primary multiphotonic absorption and no macroscopic chemical reactions were observed below the breakdown threshold.

De Montgolfier, PH.↗

NASA NTRS1972

Dynamic response of a plane-symmetrical exothermic reaction center.

?sger,An analysis of the dynamic behavior of an idealized, plane-symmetrical exothermic reaction center is presented. The conservation equations for the reaction center are combined and yield a single integral equation expressing a nonlinear transfer function of the system for which the input is provided by a given time profile of the heat released per unit mass while the output gives the pressure pulse it generates under the restriction of plane-symmetrical motion. The solution is governed by a Daumk]hler number. For a given form of the exothermic power pulse profile, the dynamic behavior of the system is completely specified in terms of only this Daumk]hler number and the heat of reaction per unit mass of the combustible medium. Specific solutions are worked out for a set of typical elementary power pulse profiles, and the practical significance of the results is illustrated by their application to the problem of transition to detonation in an explosive gas.

Meyer, J. W.↗

NASA NTRS1972

Blast waves in rotating media.

The model investigated involves a cylindrically symmetric blast wave generated by an infinitely long line explosion in a cold and homogeneous gas rotating rigidly in its self-gravitational field. It is found that within the context of rotation in a gravitational field a blast wave will not adopt the one-zone form familiar from similarity solutions but, rather, a two-zone form. The inner compression zone arises as a response to the presence of the restoring force, which drives a rarefaction wave into the outer compression zone.

Rossner, L. F.↗

NASA NTRS1971

Monitoring of explosive/pyrotechnic performance.

Utilization of performance monitoring techniques for acceptance, lot qualification, and comparison testing, as well as to provide engineering guidelines for systems design. Test techniques and apparatus have been developed to evaluate the performance of squibs, initiators, gas generating cartridges, detonators, and linear explosives for aerospace applications. A variety of devices has been tested in each of these apparatuses, including the Apollo Standard Initiator, the Apollo End Detonating Cartridge, and the mild detonating fuse and flexible linear shaped charge.

Bement, L. J.↗

NASA NTRS1971

Interrelationship of nondestructive testing to fault determination.

Several nondestructive test techniques have been developed for electroexplosive devices. The bridgewire will respond, when pulsed with a safe level current, by generating a characteristic heating curve. The response is indicative of the electrothermal behavior of the bridgewire-explosive interface. Bridgewires which deviate from the characteristic heating curve have been dissected and examined to determine the cause for the abnormality. Deliberate faults have been fabricated into squibs. The relationship of the specific abnormality and the fault associated with it is discussed.

Menichelli, V. J.↗

NASA NTRS1972

Review of sonic-boom simulation devices and techniques.

Research on aircraft-generated sonic booms has led to the development of special techniques to generate controlled sonic-boom-type disturbances without the complications and expense of supersonic flight operations. This paper contains brief descriptions of several of these techniques along with the significant hardware items involved and indicates the advantages and disadvantages of each in research applications. Included are wind tunnels, ballistic ranges, spark discharges, piston phones, shock tubes, high-speed valve systems, and shaped explosive charges. Specialized applications include sonic-boom generation and propagation studies and the responses of structures, terrain, people, and animals. Situations for which simulators are applicable are shown to include both small-scale and large-scale laboratory tests and full-scale field tests. Although no one approach to simulation is ideal, the various techniques available generally complement each other to provide desired capability for a broad range of sonic-boom studies.

Edge, P. M., Jr.↗

NASA NTRS1972

Apollo 14 active seismic experiment.

Explosion seismic refraction data indicate that the lunar near-surface rocks at the Apollo 14 site consist of a regolith 8.5 meters thick and characterized by a compressional wave velocity of 104 meters per second. The regolith is underlain by a layer with a compressional wave velocity of 299 meters per second. The thickness of this layer, which we interpret to be the Fra Mauro Formation, is between 16 and 76 meters. The layer immediately beneath this has a velocity greater than 370 meters per second. We found no evidence of permafrost.

Watkins, J. S.↗

NASA NTRS1972

Experimental and theoretical investigation of stress wave attenuation in fiber reinforced composites.

The propagation of an initialrcidrical pressure pulse through a linear elastic fiber reinforced composite medium is analysed, both experimentally and analytically. In the experiment, tests were performed on plates with single and multiple circular inclusions embedded in a matrix of lower characteristic impedance. Sharp compression pulses were generated at an edge of the plate. Strain gages were mounted on various positions of the plate to determine the attenuation of the transient stress in the fiber reinforced composite. The qualitative analytical treatment is based on the methods of propagating stress discontinuities. Computer programs were written to numerically determine the changes in the shape of the leading wave front and the stresses immediately behind it. Experimental results for the attenuation of stress wave on steel-aluminum and steel-brass fiber-matrix composites compared very well with the computed analytical results when the applied pressure is generated by small explosive charges. The results did not compare well when the applied pressure is generated by projectile impact.

Yang, J. C. S.↗

NASA NTRS1972

Shock melting and vaporization of metals.

The effect of initial porosity on shock induction of melting and vaporization is investigated for Ba, Sr, Li, Fe, Al, U, and Th. For the less compressible of these metals, it is found that for a given strong shock-generation system (explosive in contact, or flyer-plate impact) an optimum initial specific volume exists such that the total entropy production, and hence the amount of metal liquid or vapor, is a maximum. Initial volumes from 1.4 to 2.0 times crystal volumes, depending on the metal sample and shock-inducing system, will result in optimum post-shock entropies.

Ahrens, T. J.↗

NASA NTRS1970

Galactic astronomy; Proceedings of the Second Summer Institute for Astronomy and Astrophysics, State University of New York, Stony Brook, N.Y., June 19-July 17, 1968. Volumes 1 & 2.

Basic problems on the structure of our galaxy are presented. The essentially spiral structure of the galaxies is examined by a theory of the spiral shape, and by a study of the spiral structure with the 21-cm line of neutral hydrogen. Irregular spirals are discussed, and some problems that arise as a result of large deviations from the regular spiral structure are treated. The density wave theory of spiral structure is compared with the observed spiral structure of the galaxies. A section on the star migration technique, which is used to test the density wave theory of galactic spirals, is included. The interstellar medium is described in terms of such phenomena as supernova explosions and cosmic rays, both of which contribute to the energy balance of the medium. Other topics that are germaine to a description of the interstellar medium are the UV spectrum, kinematics of interstellar clouds, and ionization equilibrium. The implications of spiral galactic shock pattern on star formation along spiral arms are investigated, and by means of a blast wave model, it is shown that a hydrodynamic shock of galactic scale exists in galaxy M82.

Chiu, H.-Y.↗