Directed Energy Interception of Satellites

High power Earth and orbital-based directed energy (DE) systems pose a potential hazard to Earth orbiting spacecraft. The use of very high power, large aperture DE systems to propel spacecraft is being pursued as the only known, feasible method to achieve relativistic flight in our NASA Starlight and Breakthrough Starshot programs. In addition, other beamed power mission scenarios, such as orbital debris removal and our NASA program using DE for powering high performance ion engine missions, pose similar concerns. It is critical to quantify the probability and rates of interception of the DE beam with the approximately 2000 active Earth orbiting spacecraft. We have modeled the interception of the beam with satellites by using their orbital parameters and computing the likelihood of interception for many of the scenarios of the proposed systems we are working on. We are able to simulate both the absolute interception as well as the distance and angle from the beam to the spacecraft, and have modeled a number of scenarios to obtain general probabilities. We have established that the probability of beam interception of any active satellite, including its orbital position uncertainty, during any of the proposed mission scenarios is low ($\approx10^{-4}$). The outcome of this work gives us the ability to predict when to energize the beam without intercept, as well as the capability to turn off the DE as needed for extended mission scenarios. As additional satellites are launched, our work can be readily extended to accommodate them. Our work can also be used to predict interception of astronomical adaptive optics guide-star lasers as well as more general laser use.Comment: 47 pages, 8 figure

Correlation of transient spectra with performance in coaxial plasma guns

Two channel transient voltage digitizer for correlation of transient spectra with performance in coaxial, argon plasma gun

Controlled generation of large volumes of atmospheric clouds in a ground-based environmental chamber

Atmospheric clouds were generated in a 23,000 cubic meter environmental chamber as the first step in a two part study on the effects of contaminants on cloud formation. The generation procedure was modeled on the terrestrial generation mechanism so that naturally occurring microphysics mechanisms were operative in the cloud generation process. Temperature, altitude, liquid water content, and convective updraft velocity could be selected independently over the range of terrestrially realizable clouds. To provide cloud stability, a cotton muslin cylinder 29.3 meters in diameter and 24.2 meters high was erected within the chamber and continuously wetted with water at precisely the same temperature as the cloud. The improved instrumentation which permitted fast, precise, and continual measurements of cloud temperature and liquid water content is described

Enhancement of ion cyclotron waves in hydrogen helium mixtures

Metastable helium atom addition to hydrogen plasma for ion cyclotron mode enhancemen

Design und Synthese elektronenleitender Materialien

Im Rahmen der vorliegenden Arbeit wurden verschiedene teilfluorierte Arylphosphane synthetisiert und hinsichtlich ihrer elektronenleitenden Eigenschaften getestet. Der Einfluss der Oxidation am Phosphor-Atom mit Sauerstoff, Schwefel und Selen, sowie die Einführung elektronenziehender Arylsubstituenten wurde untersucht. Das C3-symmetrische Derivat, P(C6F4PPh2)3, zeigt in electron-only Messungen n-leitende Eigenschaften, was auch durch den Einsatz in einer organischen Solarzelle gezeigt werden konnte. Verbindungen mit höherer Elektronenaffinität stellen z. B. literaturbekannte Perfluorphenazin- und Perfluorazobenzol-Derivate dar. Quantenmechanische Betrachtungen sowie ESR-Messungen im Rahmen dieser Arbeit zeigten eine gute Delokalisierung der SOMOs der Radikalanionen über das gesamte Molekül, was für die Elektronenleitung von Vorteil sein sollte. Cyclovoltammetrische Messungen belegen die hohen Elektronenaffinitäten. Für das aus der Literatur bereits bekannte Octafluor-4,4'-azopyridin konnte eine Elektronenaffinität gefunden werden, die sogar die von C60 überschreitet, das als Elektronenleiter in organischen Solarzellen eingesetzt wird. Mit der Zielsetzung der Verbesserung der filmbildenden Eigenschaften und der zukünftig angedachten Synthese sternförmiger Azo-Verbindungen wurden verschiedene asymmetrische Azo-Verbindungen mit hoher Elektronenaffinität dargestellt und vollständig charakterisiert. C5NF4-NN-C6F4CN zeigt in organischen n-Kanal-Feldeffekttransistoren elektronenleitende Eigenschaften

Quantitative separation of small amounts of rare earths from thorium, uranium, and zirconium by ion exchange

A successful method has been developed for the determination of certain rare earths in thorium in the fractional ppm range. The procedure is based on the ion-exchange chromatographic separation of the rare earths plus added yttrium carrier from the thorium, followed by emission spectrometric determination of the rare-earth impurities in the yttrium carrier. A simultaneous separation from the rare earths of the common element impurities present in the thorium has been accomplished. A high degree of compensation for procedural errors is achieved by the use of a pure rare earth as both the carrier in the separation and purification procedure and the matrix material in the spectrographic determination

E-identiteet Eesti ja Euroopa Liidu õigusruumis: Euroopa Parlamendi ja Nõukogu e-identimise ja e-tehingute jaoks vajalike usaldusteenuste määruse kohaldamine Eestis - kujunemislugu, probleemid ja ellseisvad väljakutsed

http://www.ester.ee/record=b449772