Unified theory of SAR arc formation at the plasmapause
Stable auroral red arcs generation at plasmapause from ion cyclotron wave turbulent dissipation of ring current proton energy
Cornwall, J. M.↗
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A mathematical model of the arc Pioneer 6/7 plasma probe
Mathematical model of arc Pioneer 6/7 plasma probe electrostatic analyzer responding to monoenergetic unidirectional charged particle beam
Day, J. R.↗
The relationship of the plasmasphere and the stable auroral red arcs in the magnetic storm of October 29 to November 7, 1968
Plasmaspheric ambient hydrogen and helium atomic cations density measurement by OGO 5 ion mass spectrometer during magnetic storm, noting relationship to auroral red arcs
Chappell, C. R.↗
A higher performance electric-arc-driven shock tube
High performance electric arc driven shock tube for shock velocities to 45 km/sec and test times over 4 microseconds, using 80/20 helium-hydrogen mixture
Menard, W. A.↗
Pulsed high-power arc heater with improved cathode and triggering mechanism
System employs pulsed, constricted arc heater capable of multi-MW power, permitting quasi-stationary flow conditions during latter half of pulse of about 5 msec. System description is given.
Dethlefsen, R.↗
Arc protection system for high-power RF amplifiers
Protective system prevents damage or destruction of high-power RF amplifiers by arcs which may occur in output transmission line. Advantages of system are listed.
Chernoff, R. C.↗
FORTRAN program for computing coordinates of circular-arc, single and tandem, turbine and compressor, blade sections on a plane
Coordinates for circular arc blade section of aircraft high speed compressor gas turbines were computed using FORTRAN 4 program. Aerodynamic configurations studied include single segment airfoils, airfoils with slots, and mutiple segment tandem arranged airfoil.
Mcnally, W. D.↗
Temporal survey of electron number density and electron temperature in the exhaust of a megawatt MPD-Arc thruster
Temporal and radial profiles are obtained 30 cm downstream from the anode for two peak arc currents (11.2 kA and 20 kA) and for various auxiliary magnetic fields (0, 1.0 T, and 2.0T) using the Thomson scattering technique. Average density and temperature are relatively constant for over 100 microseconds with significant fluctuations. Radial profiles obtained are relatively flat for 4 cm from the axis. Compared to earlier 20 cm data, the exhaust density has decreased significantly, the average temperature (4.6 eV) has not changed, and the density hole with an auxiliary magnetic field has enlarged.
Michels, C. J.↗
Electrothermal oscillations and the quasilinear theory of electron enthalpy fluctuations in magnetohydrodynamic generators and magnetoplasmadynamic arc thrusters
Flucturations in electron density and temperature coupled through OHM's Law are studied for MHD power generator and MPD arc thruster applications. The dispersion relation based on linear theory is derived, and the two limiting cases of infinite ionization rate and frozen flow are examined. The nonlinear effects of the frozen flow case are then studied in the quasilinear limit. Equations are derived for the amplitude of the fluctuation and its effect upon Ohm's Law and the electron temperature equation. Conditions under which a steady state can exist in the presence of the fluctuation are examined, and effective transport properties are determined.
Smith, J. M.↗
Superalloy material test in a plasma arc tunnel
Seven superalloy models were tested in a plasma arc tunnel at the peak heating condition existing on the space shuttle orbiter's lower surface during a low cross-range entry. The models were 3 x 3 in. flat surfaces, nominally 0.01 to 0.02 in. thick, and were held in a water-cooled wedge holder at a 60 deg angle of attack. Five test models were recycled 25 times for 10 min periods (two were recycled 50 times) in a Mach 4.6 test stream, with the model's leading edge temperature maintained at 2200 F (2000 F in one case).
Land, D. W.↗
The ionosphere during a subauroral red arc
The enhancements of the red 6300A line in the midlatitudes during maximum solar activity are discussed. From Explorer 31 and OGO-4 satellite data, electron and ion temperatures were obtained at altitudes of 880km and 2500km. It was found that there is an increased plasma temperature in the region of the optical emissions, a difference of 1000k between the plasma temperature at 880km and that at 2100km, and the ion temperatures are less than the electron temperatures. It is concluded that red arcs are observed only when there is heat flow from above, combined with decreased density caused by composition changes at the lower boundary.
Maier, E.↗
Systematic two-dimensional cascade tests. Volume 3: Slotted double circular-arc hydrofoils
Performance parameters are presented for cascades of slotted double circular-arc hydrofoils tested over a range of systematically introduced variables in a rectilinear cascade tunnel which uses water as the test medium. Cascade configurations included various combinations of an inlet flow angle of 50, 60 and 70 deg; a cascade solidity of 0.75, 1.00 and 1.50; a hydrofoil camber angle of 20, 30, 40 and 45 deg; and angles of incidence between positive and negative stall. The slot was positioned at the 45 percent chord station and the slot exit width was 0.047-in. Tests were also performed with the slot positioned at the 35 percent chord station and with slot widths of 0.63 and 0.094-in. These data were correlated to indicate the effects of slot location and slot width on minimum loss incidence and deviation angles. In addition, a comparison is presented of the performance parameters for cascades of slotted and unslotted hydrofoils.
Columbo, R. M.↗
Short arc optical survey techniques
The effect of the gravity parameter, mu, the choice and local survey of the fixed origin station, and the choice of initial datum on the results of short arc satellite survey adjustments were investigated using GEOS 1 MOTS optical observations from 13 stations. It is concluded that each of these parameters has an effect on derived network scale on the order of 0.000002 for the nominal variations used. A particular solution using assumed best available values for these parameters is recommended.
Berbert, J. H.↗
Vacuum ultraviolet radiometry with a stabilized hydrogen arc.
Use of the spectral radiation emitted from a dense hydrogen plasma of at least 12,000 K, which is in local thermodynamic equilibrium (LTE), as a light source for vacuum UV radiometry. Its spectroscopic qualities are exactly known, and except for a few strongly Stark-broadened Lyman lines, its spectrum in the vacuum UV is essentially continuous. The calculated continuum output of this source for typical operating conditions is compared with the UV output of the tungsten strip lamp and the carbon arc.
Ott, W. R.↗
Postulation of the arc restrike mechanisms for exploding wires and tubes.
The many facets of exploding wire restrikes are studied. They are related to the cylindrical shock wave which pumps down the density of the center region of a line energy source or around the surface of the heated wire continuously to a lower density. When the density of any region is pumped down to lower than Paschen's electric breakdown criteria, restrike occurs. The cylindrical shocks occurring in exploding wires are, in general, divided into two types. In the first type the shock is generated by the wire explosion and in the second type the shock is generated by the heat conduction of the wire to the surrounding gas. Application of this mechanism to exploding tubes will enable us to create arc channels in arbitrary gaseous atmospheres with controllable plasma density with the contamination excluded. Neutral density shielded plasma experiments, therefore, can be conducted in a controllable environment.
Cheng, D. Y.↗
Temporal survey of electron number density and electron temperature in the exhaust of a megawatt MPD-arc thruster.
Temporal and radial profiles are obtained 30 cm downstream from the anode for two peak arc currents (11.2 kA and 20 kA) and for various auxiliary magnetic fields (0, 1.0 T, and 2.0 T) using the Thomson scattering technique. Average density and temperature are relatively constant for over 100 microseconds with significant fluctuations. Radial profiles obtained are relatively flat for 4 cm from the axis. Compared to earlier 20 cm data, the exhaust density has decreased significantly, the average temperature has not changed, and the density ?hole' with an auxiliary magnetic field has enlarged.
Michels, C. J.↗
Oxidation of boron nitride in an arc heated jet.
Two grades of hot pressed boron nitride and a boron nitride composite were subjected to oxidation tests in a 2.5 megawatt atmospheric arc jet. The results showed that fabrication and/or composition influenced thermal shock and oxidation resistance. Changes in surface structure and recession due to oxidation suggest correlation with specimen composition. The boron nitride composite reacted with the oxygen in the hot subsonic airstream to produce a glassy coating on the hot face surface.
Buckley, J. D.↗
Correlated satellite measurements of low-energy electron precipitation and ground-based observations of a visible auroral arc.
A comparison of low-energy charged-particle intensities measured with the low-altitude satellite Injun 5 and a ground-based observation of an auroral arc at Fort Churchill on December 21, 1968, during late local evening has established that an intense precipitation band of electron intensities provides the primary energy influx for the auroral light. This precipitation event was located poleward of and adjacent to the trapping boundary for more energetic electron (above 45 keV) intensities. Proton and electron intensities similar to those in the plasma sheet in the magnetotail were observed in a substantially less-intense zone positioned equatorward of and adjacent to the trapping boundary. The intense precipitation band of electron intensities poleward of the trapping boundary is interpreted as the signature of direct acceleration of magnetosheath electrons into the earth's atmosphere.
Ackerson, K. L.↗