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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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Physical constants of semicircular canals from measurement of single neural activity in anesthesized cat brain stem under constant angular acceleration
Research project summaries on cosmic rays, accelerator physics, linear accelerators, nuclear spectroscopy and structure, cyclotrons, radioactivity, and nuclear physics theory
A g cueing microcontroller is described which consists of a tandem pair of microprocessors, dedicated to the task of simulating pilot sensed cues caused by gravity effects. This task includes execution of a g cueing model which drives actuators that alter the configuration of the pilot's seat. The g cueing microcontroller receives acceleration commands from the aerodynamics model in the main computer and creates the stimuli that produce physical acceleration effects of the aircraft seat on the pilots anatomy. One of the two microprocessors is a fixed instruction processor that performs all control and interface functions. The other, a specially designed bipolar bit slice microprocessor, is a microprogrammable processor dedicated to all arithmetic operations. The two processors communicate with each other by a shared memory. The g cueing microcontroller contains its own dedicated I/O conversion modules for interface with the seat actuators and controls, and a DMA controller for interfacing with the simulation computer. Any application which can be microcoded within the available memory, the available real time and the available I/O channels, could be implemented in the same controller.
The physiological effects of forces resulting in radial acceleration, sustained linear acceleration, impact, or vibration are identified. Tolerance limits are presented for these forces.
The hard X-ray emission from 28 large solar events has been analyzed in order to search for pulsations in intensity profiles. Periodicity occurred in 26 events, usually soon after the onset, with periods in the range 10-100 s. Pulsations occurring at common frequencies in different energy bands are observed to be closely in phase. Periodic behavior in hard X-ray emission is related to that at microwave and decametric wavelengths. The observations are briefly discussed in terms of two models: that of McClean et al. (1971), applied to X-ray emission, and that of Brown and Hoyng (1975). As periodicity is normal in extended hard X-ray bursts and occurs through a broad energy band, it is probably directly related to a principal flare-acceleration mechanism. These observations constrain possible mechanisms of flare acceleration and physical properties of the acceleration region.
Superconducting linear accelerator and use of superconductivity at low temperatures in physics experiments
From radio observations it is known that two distinct groups of phenomena occur in large solar flares. The phenomena are related to an impulsive phase of approximately 100 s duration in the early stage of a flare and a following second phase lasting for tens of minutes. A study is presented of the limb-occulted flare event of July 22, 1972, giving particular attention to the second stage particle acceleration. The study takes into account hard X-ray, energetic particle, and radio observations. The conducted analysis shows that second stage acceleration is physically distinct from the impulsive phase, and is characterized by continuous and widespread electron acceleration to high energies, most likely by the type II burst shock wave.
Beam foil spectroscopy using van de Graaff accelerator, considering applications to atomic physics research and teaching
The Drop Dynamics Module houses an acoustic positioning system which counteracts the effects of small accelerations of a spacecraft and thus allows long-term study of free-floating materials such as liquid drops. The acoustic positioning system provides an acoustic 'well' in the center of the experiment chamber. Data collection is by cinematographic photography. The module subsystems are discussed.
Human adaptation to altitude, heat, cold, physical exertion, acceleration, radiation, in space flight
Maximum permissible concentrations of oxygen and carbon dioxide in a controlled atmosphere were determined by evaluating their effects on human gas exchange, blood coagulation, and tolerances to acute hypoxia, acceleration, and physical loads. It was found that functional disturbances depend on the concentration of respiratory gases and the length of stay in an altered atmosphere. By changing the atmospheric composition and by bringing the gaseous environment into accordance with the work and rest regimen and energy expenditures, the general reactivity of the body changes favorably.
An analysis of published data are presented as well as the results of experiments which show that the state of weightlessness and hypodynamia result in a reduced orthostatic and vestibular resistance, increased sensitivity to infections, decreased endurance of accelerations and physical exercises, and altered reactivity of the organism to drugs. Various consequences of weightlessness on the human body, especially weightlessness combined with other factors linked to long space flights are also considered.
The dynamics of the expanding corona are discussed emphasizing the physical processes which accelerate the plasma as it flows away from the Sun. The solar wind plays a dominant role in the energy balance of the part of the corona in which it originates. The wind acceleration processes, in large part, with the mechanisms that transport energy to the corona in the first place.
A group of 12 highly trained athletes and a group of 12untrained students were subjected to passive changes of position on a tilt table and positive accelerations in a centrifuge. During a 20 min tilt, including two additional respiratory maneuvers, the number of faints and average cardiovascular responses did not differ significantly between the groups. During linear increase of acceleration, the average blackout level was almost identical in both groups. Statistically significant coefficients of product-moment correlation for various relations were obtained. The coefficient of multiple determination computed for the dependence of acceleration tolerance on heart-eye distance and systolic blood pressure at rest allows the explanation of almost 50% of the variation of acceleration tolerance. The maximum oxygen uptake showed the expected significant correlation to the heart rate at rest, but not the acceleration tolerance, or to the cardiovascular responses to tilting.
The coaxial plasma accelerator for use as a projectile accelerator is discussed. The accelerator is described physically and analytically by solution of circuit equations, and by solving for the magnetic pressures which are formed by the j cross B vector forces on the plasma. It is shown that the plasma density must be increased if the accelerator is to be used as a projectile accelerator. Three different approaches to increasing plasma density are discussed. When a magnetic field containment scheme was used to increase the plasma density, glass beads of 0.66 millimeter diameter were accelerated to 7 to 8 kilometers per second velocities. Glass beads of smaller diameter were accelerated to more than twice this velocity.
Possibilities are considered for probing physical conditions in the solar corona with strong EUV resonance lines from ions such as N V, O VI, Ne VIII, Mg X, and Si XII. Through measurements of the intensities and profiles of EUV spectral lines with coronagraphic instrumentation employing normal incidence reflecting optics, it is possible to acquire information on electron, proton, and ion temperatures and velocity distributions; electron, H I, and ion densities; mass flow and nonthermal velocities; and chemical abundances. This information will provide critical empirical constraints on physical processes responsible for plasma heating, solar wind acceleration, and transport of mass, momentum, and energy in the solar corona, as well as providing constraints on theoretical models for solar and stellar coronae and mass loss.
Solar flares studied in the gamma ray region provide essential information on accelerated nuclei that can be obtained in no other way. A multitude of physical processes, such as particle acceleration, nuclear reactions, positron and neutron physics, and kinematical line broadening, come into consideration at gamma ray energies. Gamma ray observations are complementary to hard X ray observations, since both provide information on accelerated particles. It appears that only in the gamma ray region do these particles produce distinct spectral lines.
The theories of particle acceleration along polar field lines are reviewed, and the total energization of the charge separated plasma is summarized, when pair creation is absent. The application of these theories and plasma supply to pulsars is discussed, with attention given to the total amount of electron-positron plasma created and its momentum distribution. Various aspects of radiation emission and transport are analyzed, based on a polar current flow model with pair creation, and the phenomenon of marching subpulses is considered. The coronation beaming and the relativistically expanding current sheet models for pulsar emission are also outlined, and the paper concludes with a brief discussion of the relation between the theories of polar flow with pair plasma and the problem of the energization of the Crab Nebula.