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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 73 records · Page 4

Mass distribution of orbiting man-made space debris

Three ways of producing space debris were considered, and data were analyzed to determine mass distributions for man-made space debris. Hypervelocity (3.0 to 4.5 km/sec) projectile impact with a spacecraft wall, high intensity explosions and low intensity explosions were studied. For hypervelocity projectile impact of a spacecraft wall, the number of fragments fits a power law. The number of fragments for both high intensity and low intensity explosions fits an exponential law. However, the number of fragments produced by low intensity explosions is much lower than the number of fragments produced by high intensity explosions. Fragment masses down to 10 to the -7 power gram were produced from hypervelocity impact, but the smallest fragment mass resulting from an explosion appeared to be about 10 mg. Velocities of fragments resulting from hypervelocity impact were about 10 m/sec, and those from low intensity explosions were about 100 m/sec. Velocities of fragments from high intensity explosions were about 3 km/sec.

Bess, T. D.↗

Theory of an Electromagnetic Mass Accelerator for Achieving Hypervelocities

It is shown that for any electromagnetic accelerator which employs an electromagnetic force for driving the projectile and uses the projectile as the heat sink for the energy dissipated in it by ohmic heating, the maximum velocity attainable without melting is a function of the mass of the projectile. Therefore, for hypervelocities a large projectile mass is required and thus a power supply of very large capacity is necessary. It is shown that the only means for reducing the power requirement is maximizing the gradient of the mutual inductance. In the scheme of the sliding-coil accelerator investigated herein, the gradient of the mutual inductance is continuously maintained at a high value. It is also shown that for minimum length of the accelerator, the current must be kept constant despite the rise in induced voltage during acceleration. The use of a capacitor bank as an energy source with the condition that the current be kept constant is investigated. Experiments at low velocities are described.

Thom, Karlheinz↗

A curvature-based mechanism for the spontaneous emission of electromagnetic radiation at curved plasma–vacuum interfaces

In this work, we derive from first principles the dispersion relation for electromagnetic radiation that is spontaneously emitted at a 2D curved plasma–vacuum interface in the absence of both background and external electric and magnetic fields. This plasma geometry is motivated by plasmas generated through hypervelocity impact projectiles—an area that is of importance to satellite safety in the aerospace community, and may be of importance for the developing study of projectile impact-driven inertial confinement fusion. We find spontaneous radiation occurs when thermal surface waves propagate along the edge of a circular plasma, with a frequency lower than the plasma frequency and spatial decay proportional to 1/r. This is distinct from more well-known mechanisms of radiation, in which the radiation frequency is greater than or equal to the plasma frequency. This theory is validated against 2D, electromagnetic particle-in-cell simulations and shows reasonable agreement. Finally, we discuss the effects of plasma geometry and attribute the radiation generation mechanism to the acceleration of charged surface waves as they traverse azimuthally along a curved path.

Lau, Raymond (ORCID:0000000299318101)↗

Study of equilibrium air total radiation.

Equilibrium air total radiation mechanism, vacuum UV radiation and relation to hypervelocity entry studied, using shock tube blunt model test flow

ATMOSPHERIC RADIATION↗

Study of equilibrium air total radiation.

Equilibrium air total radiation mechanism, vacuum UV radiation and relation to hypervelocity entry studied, using shock tube blunt model test flow

VACUUM ULTRAVIOLET↗

Predicting multi-wall structural response to hypervelocity impact using the hull code

Previously, multi-wall structures have been analyzed extensively, primarily through experiment, as a means of increasing the meteoroid/space debris impact protection of spacecraft. As structural configurations become more varied, the number of tests required to characterize their response increases dramatically. As an alternative to experimental testing, numerical modeling of high-speed impact phenomena is often being used to predict the response of a variety of structural systems under different impact loading conditions. The results of comparing experimental tests to Hull Hydrodynamic Computer Code predictions are reported. Also, the results of a numerical parametric study of multi-wall structural response to hypervelocity cylindrical projectile impact are presented.

Schonberg, William P.↗

Considerations of Oblique Impacts of Non-Spherical, Graphite-Epoxy Projectiles

The DebriSat hypervelocity impact experiment, performed at the Arnold Engineering Development Center, is intended to update the catastrophic break-up models for modern satellites including many modern materials like structural panels of carbon-fiber, reinforced polymer (CFRP). Subsequent to the experiment, fragments of the DebrisSat have been extracted from porous, catcher panels, and thus far, one of the key observations from the collected fragments is that CFRP represents a large fraction of the fragments and that these fragments tend to be thin, flake-like structures or long, needle-like structures pointing to the need to consider non-spherical orbital debris. Previous work examined the case of an arbitrarily oriented cylindrical projectile impacting normal to the surface of a simple double-wall, Whipple shield, with a thermal blanket on the outer surface [1]. This work extends that development using numerical simulations to oblique impacts at a representative orbital speed of 7 km/s and addresses the complexities associated with that addition.

Miller, Joshua E.↗

A Technique for Obtaining Hypervelocity Impact Data by using the Relative Velocities of Two Projectiles

A facility has been developed and put into operation to determine the feasibility of obtaining hypervelocity impact data by using the relative velocities of two projectiles. The facility utilizes the technique of firing a target toward an oncoming high-velocity projectile so that the impact velocity is equal to the sum of the projectile velocity and the target velocity. A 37-millimeter powder gun is utilized to accelerate the targets, and a specially designed 22-caliber light-gas gun accelerates the impacting projectiles. The light-gas gun is operated by detonating an explosive charge which permits it to be synchronized with the firing of the 37-millimeter gun. Impact velocities as great as 21,850 ft/sec have been obtained during development of the facility. After the oncoming projectiles impact the targets fired from the 37-millimeter gun, these targets are recovered by allowing them to impact into Celotex and soft wooden blocks. The craters formed in the targets then can be observed and measured. The results of several preliminary firings of the facility are included in this report.

Kinard, William H.↗

An investigation of oblique hypervelocity impact

This report describes the results of an investigation of phenomena associated with the oblique hypervelocity impact of spherical projectiles on multi-sheet aluminum structures. A model to be employed in the design of meteoroid and space debris protection systems for space structures is developed. The model consists of equations relating crater and perforation damage of a multi-sheet structure to parameters such as projectile size, impact velocity, and trajectory obliquity. The equations are obtained through a regression analysis of oblique hypervelocity impact test data. This data shows that the response of a multi-sheet structure to oblique impact is significantly different from its response to normal hypervelocity impact. It was found that obliquely incident projectiles produce ricochet debris that can severely damage panels or instrumentation located on the exterior of a space structure. Obliquity effects of high-speed impact must, therefore, be considered in the design of any structure exposed to the hazardous meteoroid and space debris environment.

Schonberg, William P.↗

An analysis of penetration and ricochet phenomena in oblique hypervelocity impact

An experimental investigation of phenomena associated with the oblique hypervelocity impact of spherical projectiles on multisheet aluminum structures is described. A model that can be employed in the design of meteoroid and space debris protection systems for space structures is developed. The model consists of equations that relate crater and perforation damage of a multisheet structure to parameters such as projectile size, impact velocity, and trajectory obliquity. The equations are obtained through a regression analysis of oblique hypervelocity impact test data. This data shows that the response of a multisheet structure to oblique impact is significantly different from its response to normal hypervelocity impact. It was found that obliquely incident projectiles produce ricochet debris that can severely damage panels or instrumentation located on the exterior of a space structure. Obliquity effects of high-speed impact must, therefore, be considered in the design of any structure exposed to the meteoroid and space debris environment.

Schonberg, William P.↗

Analysis of oblique hypervelocity impact phenomena

This paper describes the results of an experimental investigation of phenomena associated with the oblique hypervelocity impact of spherical projectiles on multisheet aluminum structures. A model that can be employed in the design of meteoroid and space debris protection systems for space structures is developed. The model consists of equations that relate crater and perforation damage of a multisheet structure to parameters such as projectile size, impact velocity, and trajectory obliquity. The equations are obtained through a regression analysis of oblique hypervelocity impact test data. This data shows that the response of a multisheet structure to oblique impact is significantly different from its response to normal hypervelocity impact. It was found that obliquely incident projectiles produce ricochet debris that can severely damage panels or instrumentation located on the exterior of a space structure. Obliquity effects of high-speed impact must, therefore, be considered in the design of any structure exposed to a meteoroid or space debris environement.

Schonberg, William P.↗

Penetration and ricochet phenomena in oblique hypervelocity impact

An experimental investigation of phenomena associated with the oblique hypervelocity impact of spherical projectile on multisheet aluminum structures is described. A model that can be employed in the design of meteoroid and space debris protection systems for space structures is developed. The model consists of equations that relate crater and perforation damage of a multisheet structure to parameters such as projectile size, impact velocity, and trajectory obliquity. The equations are obtained through a regression analysis of oblique hypervelocity impact test data. This data shows that the response of a multisheet structure to oblique impact is significantly different from its response to normal hypervelocity impact. It was found that obliquely incident projectiles produce ricochet debris that can severely damage panels or instrumentation located on the exterior of a space structure. Obliquity effects of high-speed impact must, therefore, be considered in the design of any structure exposed to the meteoroid and space debris environment.

Schonberg, William P.↗

Magnetic effects of shock and their implications for lunar magnetism. II

Synthetic breccias were produced by hypervelocity impact of projectiles on basalt powders in order to study the magnetization acquired during shock lithification of soil. It was found that some of the lithified products record the field at the point where they land, while others carry the original primary remanence. Even those rocks recording the direction of the ambient field did not always faithfully record the intensity of the field. When rocks were exposed to shock, it was found that the magnetic hardness of a rock has a profound effect on its magnetic response. Shock effects are seen at shock levels of less than 10 kbar, which suggests that lunar samples may have been shock-demagnetized.

Cisowski, S. M.↗