The Fast Plasma Investigation (FPI) was developed for flight on the Magnetospheric Multiscale (MMS) mission to measure the differential directional flux of magnetospheric electrons and ions with unprecedented time resolution to resolve kinetic-scale plasma dynamics. This increased resolution has been accomplished by placing four dual 180-degree top hat spectrometers for electrons and four dual 180-degree top hat spectrometers for ions around the periphery of each of four MMS spacecraft. Using electrostatic fieldof-view deflection, the eight spectrometers for each species together provide 4pi-sr field-ofview with, at worst, 11.25-degree sample spacing. Energy/charge sampling is provided by swept electrostatic energy/charge selection over the range from 10 eV/q to 30000 eV/q. The eight dual spectrometers on each spacecraft are controlled and interrogated by a single block redundant Instrument Data Processing Unit, which in turn interfaces to the observatory's Instrument Suite Central Instrument Data Processor. This paper describes the design of FPI, its ground and in-flight calibration, its operational concept, and its data products.

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This paper summarizes the results from a number of different voltage sag investigations. These investigations involve characterizing the voltage sag performance at a customer facility and evaluating equipment sensitivity to different voltage sag magnitudes and durations. Possible solutions to voltage sag sensitivity problems are also described.

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The effects on the nuclear magnetic resonance line shape of a polycrystalline sample resulting from combined axially symmetric electric quadrupole and anisotropic shift interactions have been calculated through the second order. The line shape of the central transition of the resonance has been shown to change smoothly from that characteristic of quadrupole effects (inverse field dependence) to that characteristic of anisotropic shift effects (direct field dependence) as the magnetic field strength is increased. Methods are given for determining the magnetic shift parameters-both isotropic and anisotropic (axial)-and the electric quadrupole coupling from line shape and shift measurements. An illustration of these methods is given, based on experimental measurements of the Al 27 spectrum in polycrystalline PrAl2. 8 R. V. Pound, Phys. Rev. 79, 685 (1950). 9 M. H. Cohen and F.

A self-contained, hand-held radiometer designed for field use has been constructed and tested. The 4.5-kilogram device, consisting of a strap-supported electronics module and a hand-held probe containing three sensors, is powered by flashlight and transistor radio batteries, uses two silicon and one lead sulfide detector, has three liquid-crystal displays, features sample-and-hold radiometric sampling, and is spectrally configured to Landsat-D's thematic mapper bands TM3 (0.63 to 0.69 micrometer), TM4 (0.76 to 0.90 micrometer), and TM5 (1.55 to 1.75 micrometers). The device was designed to collect ground-truth data for the thematic mapper and to facilitate ground-based, remote-sensing studies of natural materials in situ. Prototype instruments were extensively tested under laboratory and field conditions, with satisfactory results.

The reactivity of metal alkyls undergoing decomposition by heat offers many interesting problems of both scientific and practical interest. The production of a reactive fragment of decomposition among inert hydrocarbons might offer a means of bringing these compounds into a state of reactivity with the possible formation of more interesting products. A study of the reactivity of such fragments with hydrogen is of importance also as indicating the direction of chemical change in systems obtaining when hydrocarbons are subjected to processes of thermal degradation or "cracking." To these ends we have investigated the decomposition of several metal alkyls in the presence of various mixtures of hydrogen and ethylene.When a metal alkyl is decomposed by heat, leaving the free metal as a deposit, it seems an unavoidable assumption that the alkyl group must have existed, at least for a short space of time, as a free radical. If it can then be shown that any resulting reaction could not be attributed to the metal or to the temperature, the postulated mechanism of whatever reaction occurs must be such as to involve the alkyl radical. For this reason mercury diethyl and lead tetraethyl were chosen, since they decompose under temperature conditions which do not of themselves induce reaction of hydrogen and ethylene, and since the metals themselves do not exhibit any marked catalytic effect.

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