Investigation of laser dynamics, modulation and control by means of intra-cavity time varying perturbation Semiannual status report
Laser dynamics, control, and stabilization of optical frequency radiation
Harris, S. E.↗
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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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Rate of post-radiational recovery, with partial shielding of organs in the abdominal cavity
Rate of recovery after partial irradiation of mice and rats
Davydov, V. I.↗
Removal of flowmeter bearings from blind cavities
Bearings are removed by the application of a simple hydraulic principle using beeswax in place of a liquid.
Lindquist, J. J.↗
Investigation of laser dynamics, modulation and control by means of intra-cavity time varying perturbation Quarterly status report, 1 Nov. 1969 - 31 Jan. 1970
Tunable optical sources obtained by means of nonlinear optical techniques
Source record↗
Investigation of laser dynamics, modulation and control by means of intra-cavity time varying perturbation Quarterly status report, 1 Feb. - 30 Apr. 1970
Tunable optical sources by means of nonlinear optical techniques
Harris, S. E.↗
Active cavity radiometer, type III - An automatic, absolute standard, highly accurate detector
Instrument of simple construction operates without vacuum enclosure over wide pressure range and temperatures from 218 to 398 deg K and defines absolute radiometric scale to within less than 0.5 mW/sq cm. It has potential application to meteorology and climatology and operates on electrical substitution calorimeter principle.
Willson, R. C.↗
Apparatus for detecting the amount of material in a resonant cavity container Patent
Quantitative liquid measurements in container by resonant frequencies
Miller, J. C.↗
Experimental determination of acoustic and structural behavior of wall panel-cavity configurations exposed to sonic booms
Structural response and acoustic transmission characteristics of glass pane and standard wood frame construction wall panels subjected to sonic booms
Abele, M.↗
Rocket Combustion Instability Suppression With Cavity Resonators
Properly tuned Helmholtz resonator damping devices are an effective method for eliminating high frequency combustion instability in rocket engine thrust chambers. A program was implemented with the objective of extending Helmholtz resonator theory to thrust chamber conditions to establish a standard design procedure. By using systematic cold-flow testing and hot firings, empirical design equations were formulated. An effort is currently underway to extend the design theory to other types of acoustical damping devices such as quarter-wave tubes and slots.
R H Counts↗
Analysis of thermal environment in the thrustor cavity of space vehicles
Wind tunnel tests to determine the mechanisms involved in producing the high local heating rates in and around the thrustor nozzle in a non-firing condition are reported. The geometry of a typical nozzle installation is described. Procedures for reducing the effects of hypersonic flow interactions in order to prevent excess local heating are explained.
Chiou, J. N.↗
Alignment apparatus using a laser having a gravitationally sensitive cavity reflector
A description is given of a device for determining a true gravitational vertical. The apparatus is composed of a vertically disposed laser with a gravitationally sensitive lower regeneration reflector. The reflector enables an output beam to be developed only when the optical axis of the laser is disposed normal to the gravitationally sensitive reflective surface. In an alternative embodiment, the devices is combined with a servo system to provide a gravitationally stabilized horizontal platform.
Billman, K. W.↗
Interference Heating to Cavities Between Simulated RSI Tiles
Test results for full scale simulated surface insulation tiles on both the tunnel wall and in the free stream, for in-line and staggered tile orientations, are summarized as follows: (1) The staggered tile orientation has heating on the forward face which is a factor of 4.5 times higher than the heating to the forward face of the in-line tile orientation; (2) the longitudinal gap heating was the highest for the 0.3175 cm gap and the lowest for the 0.1587 cm gap; and (3) there was an order of magnitude decrease in the heating on the forward face of a spanwise gap when the gap size was decreased from 0.3175 cm to 0.1587 cm.
Johnson, C. B.↗
Wavelength-selective, sequential Q-switching laser cavity
Single-frequency continuous output of laser is converted into series of high-power laser pulses at high repetition rates. Applications include pollutant detection by absorption, laser gain measurements at discrete wavelengths, laser propagation measurement, and laser plasma diagnostics.
Allario, F.↗
Investigation of laser dynamics, modulation and control by means of intra-cavity time varying perturbation
Work continued on a number of projects aimed at the generation of tunable visible, infrared, and ultraviolet light; and on the control of this light by means of novel mode-locking and modulation techniques. Progress is summarized for the following projects: (1) the transient modelocking of the Nd:YAG laser and application of short optical pulses; (2) studies of the sodium-xenon excimer laser; (3) development of techniques for vacuum ultraviolet holography; and (4) studies of multiple photon pumped xenon and argon excimer lasers.
Harris, S. E.↗
Experimental investigation at Mach 8 of the effects of projections and cavities on heat transfer to a model of the Viking aeroshell
An experimental investigation into the aerodynamic heating on a Mars entry vehicle shape with several types of local surface distortion is presented. The configurations tested were 0.033-scale models of a spherically blunted 70 deg half-angle cone with two protuberances of different length, representing the tube leading to the gas chromograph mass spectrometer, and two aeroshell-bioshield attachment points of different size. These models were tested at free-stream Reynolds numbers per meter of 3.7 million and 17 million over an angle-of-attack range from 0 to 18 deg in the Langley Mach 8 variable density hypersonic tunnel. The phase change-coating technique was used to measure heat transfer coefficient. The long protuberance caused more severe interference heating than the short protuberance for the same conditions. When the short projection was located close to the edge of the aeroshell, the interference heating was greater than that on the same projection when located near the vertex. A significant increase in heat transfer coefficient was measured only on the larger aeroshell-bioshield attachment point.
Creel, T. R., Jr.↗
Investigation of laser dynamics, modulation and control by means of intra-cavity time varying perturbation
Projects aimed at the generation of tunable visible, infrared, and ultraviolet light, and on the control of this light by means of novel mode-locking and modulation techniques are discussed. During this period the following projects have been active: (1) studies of transient mode-locking of the Nd:YAG laser and the application of short optical pulses; (2) experimental investigations of the Na-Xe excimer laser system; (3) further development of techniques for vacuum ultraviolet holography; and (4) theoretical and initial experimental studies of a new device which should prove very useful for both infrared up-conversion and generation of tunable UV radiation - a two-photon resonantly pumped frequency converter.
Harris, S. E.↗
A note on the unsteady cavity flow in a tunnel
The unsteady internal cavitating flow such as the one observed in a pump or a turbine is studied for a simple two-dimensional model of a base-cavitating wedge in an infinite tunnel and it is shown how the cavitation compliance can be calculated using the linearized free streamline theory. Numerical values are obtained for the limiting case of a free jet. Two important features are: First, the cavitation compliance is found to be of complex form, having additional resistive and reactive terms beyond the purely inertial oscillation of the whole channel in 'slug flow.' Second, the compliance has a strong dependence on frequency.
Kim, J. H.↗
Investigation of laser dynamics, modulation and control by means of intra-cavity time varying perturbation
The generation of tunable visible, infrared, and ultraviolet light is examined, along with the control of this light by means of novel mode-locking and modulation techniques. Transient mode-locking of the Nd:YAG laser and generation of short tunable pulses in the visible and the alkali metal inert gas excimer laser systems were investigated. Techniques for frequency conversion of high power and high energy laser radiation are discussed, along with high average power blue and UV laser light sources.
Harris, S. E.↗