Proceedings of the First Workshop on Containerless Experimentation in Microgravity

The goals of the workshop were first to provide scientists an opportunity to acquaint themselves with the past, current, and future scientific investigations carried out in the Containerless Science programs of the Microgravity Science and Applications Div. of NASA, as well as ESA and Japanese Space Agencies. The second goal was to assess the technological development program for low gravity containerless experimentation instruments. The third goal was to obtain recommendations concerning rigorous but feasible new scientific and technological initiative for space experiments using noncontact sample positioning and diagnostic techniques

Index to 1986 NASA Tech Briefs, volume 11, numbers 1-4

Short announcements of new technology derived from the R&D activities of NASA are presented. These briefs emphasize information considered likely to be transferrable across industrial, regional, or disciplinary lines and are issued to encourage commercial application. This index for 1986 Tech Briefs contains abstracts and four indexes: subject, personal author, originating center, and Tech Brief Number. The following areas are covered: electronic components and circuits, electronic systems, physical sciences, materials, life sciences, mechanics, machinery, fabrication technology, and mathematics and information sciences

Development of a Magnetic Levitation System for Additive Manufacturing Processes

Magnetic levitation and Additive Manufacturing (AM) are both highly innovative fields that have changed the trajectory of development within a wide variety of applications. Magnetic levitation techniques offer noncontact levitation forces that highlight high compatibility with metal AM operations like Laser Directed Energy Deposition via Powder Feeding (LDED-PF) techniques. The research presented in this report aims to highlight the novel implementation of a magnetic levitation system compatible with LDED-PF operations. The suspension of a conductive paramagnetic material geometry through repulsive magnetic levitation techniques will serve as the substrate to build a part through LDED-PF operations. The research contributions are as follows: First, this research develops a novel magnetic levitation system capable of supporting AM operations. The compatibility of the levitation system has been tested through simulations and experiments. Second, the levitation system can support time-varying loads over time without losing stability during AM operations. Finally, a novel parameter to determine the compatibility of different paramagnetic materials with magnetic levitation applications was developed and verified through this research. Two magnetic levitation systems were developed. The first system was composed of a laminated core. This entailed the use of several hundred sheets assembled together to form the core within which the coils were embedded. This resulted in a reduction in eddy current losses within the core, however, the sheets sizes were predefined which resulted in the loss of flexibility for optimization. The second system was composed of a solid core system. This system was subjected to higher eddy current losses, however, offered significantly higher flexibility for optimization. The prototypes were optimized, manufactured, assembled, and tested. Both prototypes successfully highlighted the ability to levitate aluminum discs. Following the successful development of the levitation system prototypes, the next step was the development of a feedback controller to facilitate stable suspension at the desired setpoint. Through the incorporation of a simple Proportional Integral and Derivative (PID) controller using a laser sensor, the rise time was improved. However, a significantly high settling time was still encountered. To overcome this, a PID controller with a compensator component modeling the anticipated initial value of the voltage input was incorporated into the feedback PID controller. Through the implementation of the PID controller with the compensator component, the overshoot was eliminated and the settling time was reduced by 3.9 s. Subsequently, the performance of the levitation system was tested without a feedback controller within the LDED-PF machine experimentally. Copper alloys were deposited on an aluminum alloy build surface that was levitated. Under a high powder feed rate and high laser power, the levitation system was successfully able to support powder deposition activities. The build surface for powder deposition was also maximized through the incorporation of the levitation system within the AM machine. Finally, this research also develops a parameter set that utilizes the material properties of different paramagnetic materials to determine their compatibility with magnetic levitation techniques. Conventionally, there is a strong reliance on the use of experimental implementation to determine whether a material is compatible with magnetic levitation techniques. However, by comparing the ratio of electrical conductivity to the density of the material, the compatibility of the material with magnetic levitation techniques can be determined without any experimental implementation

Index to 1984 NASA Tech Briefs, volume 9, numbers 1-4

Short announcements of new technology derived from the R&D activities of NASA are presented. These briefs emphasize information considered likely to be transferrable across industrial, regional, or disciplinary lines and are issued to encourage commercial application. This index for 1984 Tech B Briefs contains abstracts and four indexes: subject, personal author, originating center, and Tech Brief Number. The following areas are covered: electronic components and circuits, electronic systems, physical sciences, materials, life sciences, mechanics, machinery, fabrication technology, and mathematics and information sciences

Fourth International Symposium on Magnetic Suspension Technology

In order to examine the state of technology of all areas of magnetic suspension and to review recent developments in sensors, controls, superconducting magnet technology, and design/implementation practices, the Fourth International Symposium on Magnetic Suspension Technology was held at The Nagaragawa Convention Center in Gifu, Japan, on October 30 - November 1, 1997. The symposium included 13 sessions in which a total of 35 papers were presented. The technical sessions covered the areas of maglev, controls, high critical temperature (T(sub c)) superconductivity, bearings, magnetic suspension and balance systems (MSBS), levitation, modeling, and applications. A list of attendees is included in the document

Index to NASA Tech Briefs, 1975

This index contains abstracts and four indexes--subject, personal author, originating Center, and Tech Brief number--for 1975 Tech Briefs

Dynamics of Liquid Metal Drops Influenced by Electromagnetic Fields

Zusammenfassung Diese Arbeit ist den Effekten gewidmet, die an der Oberfläche von Flüssigmetall im Magnetfeld auftreten können. Im Prinzip erlauben Magnetfelder, Lorentzkräfte auf flüssiges Metall auszuüben und in seinem Innern Induktionswärme zu generieren. Es ist aber auch bekannt, dass Flüssigmetall-Oberflächen durch Magnetfelder dramatische Formänderungen oder Schwingungen erfahren können. Ein Verständnis dieser Phänomene ist wichtig für sämtliche metallurgische Anwendungen, bei denen freie Oberflächen vorkommen. Als repräsentatives Problem untersuchen wir einen Tropfen aus Flüssigmetall, der eine freie Oberfläche mit einem endlichen Volumen verbindet. Wir schliessen Temperatureffekte aus und konzentrieren uns auf die Wirkung der Lorentzkraft. Wir erarbeiten ein Schema zur Klassifikation von Tropfen-Magnetfeld-Problemen basierend auf der Frequenz des Magnetfeldes und dem Shielding-Parameter des Tropfens in diesem Feld. Anhand dieses Schemas wählen wir fünf Fallstudien aus und studieren das Tropfenverhalten im i) transienten, ii) hochfrequenten und iii) mittelfrequenten Magnetfeld. Die Untersuchungen sind vorwiegend analytischer Art, nur die Mittelfrequenz-Studie ist experimentell. Die beiden wichtigsten Probleme, welche die vorliegende Arbeit zum Gegenstand hat, sind das symmetrische Zusammendrücken oder Halten von Flüssigmetalltropfen einerseits und deren azimutale Verformungen andererseits. Für das transiente Magnetfeld werden zwei Studien präsentiert, jede zu einem der beiden Hauptprobleme. Eine Verbindung zwischen transientem und hochfrequentem Feld besteht darin, das mit beiden Feldtypen stationäre Kräfte im Metall erzeugt werden können. Ein wichtiger Unterschied ist jedoch, dass transiente Felder das Metall durchdringen können, während hochfrequente Felder vom Metall abgeschirmt werden, wodurch eine Kopplung zwischen Tropfenform und Magnetfeld entsteht. Die Effekte im hochfrequenten Feld sind daher schwieriger zu modellieren. Wir präsentieren eine Hochfrequenz-Studie, in der es um das Zusammendrücken und Halten von Tropfen in einem gegebenen Magnetfeld geht. Eine zweite Hochfrequenz-Studie beschäftigt sich mit longitudinaler Levitation. Dort geben wir als einfache Tropfenform einen Flüssigmetall-Zylinder vor und ermitteln das Magnetfeld, welches die vorausgesetzte Tropfenform tatsächlich ermöglichen würde. Im mittelfrequenten Feld bieten sich für theoretische Betrachtungen die grössten Schwierigkeiten, da das Magnetfeld den Tropfen nun partiell durchdringt und kaum noch vereinfacht werden kann. Dieser Bereich wurde daher durch die fünfte Studie experimentell erkundet. Dabei wurde eine Flüssigmetall-Scheibe verwendet, welche nur zweidimensionale Verformungen ausführen kann. Die Ergebnisse der Arbeit zeigen, dass insbesondere transiente Magnetfelder gangbare Wege der analytischen Modellierung bieten. Ebenso wie hochfrequente Magnetfelder eignen sie sich zum Formen und Stützen freier Flüssigmetall-Oberflächen. Für das Studium der azimutalen Verformungen hat sich die Scheiben-Geometrie als günstig erwiesen, sowohl analytisch als auch experimentell. Insgesamt zeigt sich, dass eine Fortführung der Arbeit auf dem Gebiet der Wechselwirkung zwischen Magnetfeldern und Flüssigmetall-Oberflächen lohnenswert ist.This work is devoted to the free surface effects that occur when liquid metal is placed in a magnetic field. Principally, magnetic fields allow to exert Lorentz forces on liquid metal and to generate induction heat inside it. But it is also known that liquid metal surfaces in magnetic fields can undergo dramatic shape changes or experience oscillations. An understanding of these phenomena is crucial to all metallurgical applications showing free surfaces. As a representative problem we examine a liquid metal drop that combines a free surface with a finite volume. We exclude heat effects and focus on the consequences of the Lorentz force. To this end, we elaborate a classification scheme for liquid metal drop - magnetic field problems comprising the frequency of the magnetic field and the Shielding parameter of the drop in this field. On that basis we select five case studies involving i) transient, ii) middle-frequency and iii) high-frequency magnetic field to explore the behavior of liquid metal drops in it. We mainly use analytical means - only the middle-frequency study is experimental. The major problems we tackle concern the symmetric squeezing and supporting of drops and its azimuthal deformations, respectively. Two studies are presented for the transient magnetic field, each accounting for one of the two problems. A connection between transient and high frequency magnetic field is the possibility to exert a steady force on the liquid metal. An important difference is that transient fields can penetrate the metal while high-frequent fields are shielded by the metal resulting in a coupling between surface shape and magnetic field distribution. Therefore, the effects of high frequency magnetic fields are more difficult to model. We present one high frequency study where we presuppose the magnetic field and ask for the resulting drop shape (forward problem) and another one where we presuppose a simple surface shape and ask for the best suited magnetic field to obtain it (reverse problem). The most difficulties arise in middle-frequent magnetic fields. Here we have partial shielding which makes it necessary to solve the magnetic diffusion equation and to account for the coupling between magnetic field and drop surface at the same time. In this field, the fifth study reports experimental results on the azimuthal deformations of a liquid metal disc in an inhomogeneous inductor field. The results of the work show that especially the transient fields provide feasible ways for analytical modeling. Like high frequency fields they are suited to shape and to support liquid metal surfaces. To study azimuthal deformations, the disc geometry has proven useful - both analytically and experimentally. Overall, it still seems worthwhile to further investigate the behavior liquid metal surfaces in magnetic fields

Development of high temperature containerless processing equipment and the design and evaluation of associated systems required for microgravity materials processing and property measurements

The development of high temperature containerless processing equipment and the design and evaluation of associated systems required for microgravity materials processing and property measurements are discussed. Efforts were directed towards the following task areas: design and development of a High Temperature Acoustic Levitator (HAL) for containerless processing and property measurements at high temperatures; testing of the HAL module to establish this technology for use as a positioning device for microgravity uses; construction and evaluation of a brassboard hot wall Acoustic Levitation Furnace; construction and evaluation of a noncontact temperature measurement (NCTM) system based on AGEMA thermal imaging camera; construction of a prototype Division of Amplitude Polarimetric Pyrometer for NCTM of levitated specimens; evaluation of and recommendations for techniques to control contamination in containerless materials processing chambers; and evaluation of techniques for heating specimens to high temperatures for containerless materials experimentation

NASA Tech Briefs, Spring 1985

Topic include: NASA TU Services; New Product Ideas; Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Life Sciences; Mechanics; Machinery; Fabrication Technology; Mathematics and Information Sciences