E. O. Hulburt's research while affiliated with Washington College and other places

Publications (84)

Article
A large array of astronomical X-ray detectors can be constructed at a lunar base, and maintained there for a long time. Such an array permits development of a new astronomical subdiscipline based on collection of very large numbers of X-ray photons from bright X-ray sources With such data qualitatively new experimental issues can be addressed, in g...
Article
Transitions of the type n = 2–3 and n = 3–4 in P XIII, S XIV, Cl XV, and K XVII were observed in the spectra from linear plasmas. The 3d−4f transitions were observed in all four ions and are of potential interest for x-ray lasers. The wavelengths of the transitions were determined with an uncertainty of ±0.010 Å, and the observed wavelengths are co...
Article
The high-resolution absorption spectrum of Bi I is reported for the 2022−1307 Å region. Transitions have been observed from the 6p3 4S°3/2 ground state of Bi I to levels with J ≤ 5/2 and even parity built on the ground term 6p2 3P of Bi II. Levels with n values as large as 63 are determined from spectra observed below the 6p2 3P0 limit near 1701.79...
Article
Transitions in Ge xxiv, Ge xxv, and Ge xxvi were observed in the spectra emitted from linear plasmas that were produced by irradiating planar targets using eight line-focused beams of the Omega laser. A 3-m grazing-incidence spectrograph viewed the plasma in the axial direction. The spectral lines were quite narrow owing to the reduced ion motion a...
Article
Transitions of the type 3p63d8−3p53d9 in Sb25+ have been identified in the spectrum from a plasma produced by irradiating a planar foil target, using line-focused laser irradiation. The wavelengths in the range 44–62 Å were determined with an uncertainty of ±0.007 Å. Based on the 45 observed wavelength combinations, energy-level values were establi...
Article
Transitions of the type n = 4—5 in Ta44+, Au50+, Pb53+, and Bi54+ were observed in the spectra from laser-produced plasmas that were recorded by a grazing-incidence spectrograph. Wavelengths in the range 9—19 Å were measured with an uncertainty of ±0.015 Å and were compared with previously measured and predicted wavelengths.
Article
When an earlier paper1 was revised, the reference numbers were changed. However, because of an oversight the reference numbers in Fig. 2 of Ref. 1 were not changed, and therefore some of the reference numbers in Fig. 2 are incorrect. Below is a revised Fig. 2 that contains the correct reference numbers.
Article
Spectra of 14 Fe-like ions from Ru18+ to Gd38+ were observed with laser-produced plasmas and grazing-incidence spectrographs. The wavelengths range from 26 to 78 Å. Line identifications were made for transitions of the 3p63d8−3p53d9 array. The number of identifications varied from 42 in Ru18+ to 10 in Gd38+. Experimental values for many of the ener...
Article
The spectra of highly charged ions of the elements In, Sb, I, and Cs have been recorded by using a 3-m grazingincidence spectrograph at the University of Rochester's Laboratory for Laser Energetics. Transitions in the Na I and Mg I isoelectronic sequences have been identified. Wavelengths in the range 7–100 Å were measured to an accuracy of ± 0.02...
Article
IAUC 3822 available at Central Bureau for Astronomical Telegrams. IAUC 3822 available at Central Bureau for Astronomical Telegrams.
Chapter
This is a sequel to the section “The upper atmosphere” in the Compendium of meteorology (Malone, 1951) and is a report of the progress in the subject which has occurred since that volume went to press in 1950. Major advances have been made by means of instruments carried to great heights on rockets with which the vertical distribution of atmospheri...
Article
It is assumed that the sun emits a jet of an electrically neutral mixture of fast electrons and positive ions, and that the space between the sun and earth is filled with an ionized, electrically neutral gas. As the jet proceeds the fast electrons are slowed down and scattered by encounters with the space ionization, being continually replaced by s...
Article
Citation C. J. BECK, D. J. LOVELL, and E. O. HULBURT, "Atmospheric Attenuation at Khartoum, Sudan," J. Opt. Soc. Am. 43, 405-406 (1953) http://www.opticsinfobase.org/josa/abstract.cfm?URI=josa-43-5-405
Article
By use of the Rayleigh scattering theory for pure air, primary scattering and known upper air densities from rockets, the brightness of the zenith twilight sky was calculated and values were obtained two to four times greater than those observed at Sacramento Peak, New Mexico (J. Opt. Soc. Am. 42, 353 (1952)). The attenuation of the atmosphere ther...
Article
With a recording photometer of photopic sensitivity, measurements were made of many points in the sky during twilight for solar altitudes H = +5° to -15° for clear air and no clouds at two stations, one in Maryland, altitude 30 meters, and one on Sacramento Peak, New Mexico, altitude 2800 meters. The sky polarization on the meridian through the sun...
Chapter
In places remote from artificial illumination at night, with no moon, the luminosity of the sky is due to several sources of light, all of which are at a considerable distance. The sources are (1) radiations from the gases of the upper atmosphere, (2) polar aurorae, (3) zodiacal light, (4) comets and possibly scattered sunlight in interplanetary sp...
Article
Diffusion is treated by showing that the action of a medium on a diffusing gas is that of a dissipative force. When the theory is applied to an electrically neutral ionic gas in a gravitational field it is found that the mixture of positive and negative ions diffuses as a single gas because of the electrical polarization charges within the ionic cl...
Article
From the theory of the passage of light through a telescope and into the eye, formulas are derived for the improvement in the visual threshold of a point source, as a star, viewed in a field of light, as the sky, in terms of telescope parameters, as magnification, transmission, and entrance and exit pupils. For fields of the brightness of the dayli...
Article
The threshold illumination i at the eye from a steady source of light of 1′ angular diameter in a field of brightness b was measured for b ranging from zero to about 1500 candles per square foot. The data were obtained by five young experienced observers using both eyes unaided and with natural pupil. A bend in the i, b curve at about b = 1000 mµL...
Article
Comparison of E region observations from 1930 to 1938 of ionosphere stations scattered over the earth with the theory of ionization caused by solar radiation absorbed exponentially in a relatively quiet terrestrial atmosphere yielded the conclusions: (1) the diurnal variation of ym, the maximum-with-height value of the equivalent electron density,...
Article
DOI:https://doi.org/10.1103/PhysRev.53.670.2
Article
With a calibrated Macbeth illuminometer measurements were made of iz the brightness of the zenith sky and of ig the energy flux across a vertical plane from the twilight horizon for the depression θ of the sun below the horizon from 0° to 13°. For clear sky conditions the iz, θ and ig, θ curves did not change within 30 percent with the season from...
Article
The ionization equilibrium in the various atmospheric gases is calculated from the Saha theory on the assumption that the spectral energy curve of sunlight for ultraviolet frequencies above the limits of the principal series is that of a black body at 6000°K. A calculated region of ionization due mainly to oxygen and partly to nitrogen is found at...
Article
DOI:https://doi.org/10.1103/RevModPhys.9.44
Article
The observed optimum frequency f for long distance daylight communication averaged over the year during the period from 1923 to 1936 was found to vary with the yearly average relative sunspot number s according to the relation f=7.8(s+12)14. The march of the sunspot curve from 1749 to 1935 suggests the possibility of greater sunspot numbers in comi...
Article
The present paper continues the work on the ionization of the upper atmosphere due to the ultraviolet light of the sun, developed in a series of papers in this Journal, and takes into account as far as possible the entire meteorology of the upper atmosphere and the effects of recombination, temperature diffusion and the motions of the ions and elec...
Article
From Millikan's measurements of the intensity and the absorption coefficients of cosmic radiation the ionization in the atmosphere is calculated from sea level to 60 km. The electron density is negligibly small in this region. The ion density increases with the height to 3.5×103 ion pairs cm−3 at about 50 km and is roughly constant above this to 60...
Article
From the known amounts of the various gases of the atmosphere from sea level to about 20 km, from the observed light absorption coefficients of the gases and from the albedo of the earth's surface the temperature of the atmosphere in radiative equilibrium is calculated on the assumption that the sunlight is the only source of energy. The calculatio...
Article
Solar spectra were taken with a small quartz spectrograph at noon on November 13, 1929, and January 25, 1930, in Little America, Antarctica, by Malcolm P. Hanson of the Byrd Antarctic Expedition. The ultraviolet limit of these spectra was at about 304mumu which was the same as the ultraviolet limit of noon solar spectra taken at Washington, D.C., i...
Article
Continuing a former paper (Phys. Rev. 34 1167 1929 ) the present paper gives theoretical calculations of the changes in the ionization in the upper atmosphere with longitude. The electrical conductivity of the upper atmosphere is about 1.4 × 10-5 at noon equinox at the equator and an order of magnitude less at night. The maximum density of electron...
Article
The ultraviolet light theory of aurorae and magnetic storms, Phys. Rev. 33, 412 (1929), 34, 344 (1929), did not agree with all the facts. Making use of the further development of the theory of the outer atmosphere, Phys. Rev. 34, 1167 (1929), 35, 240 (1930), the discrepancies in the ultraviolet theory are removed with no change in the original assu...
Article
A quantitative atmospheric theory of the zodiacal light and the gegenschein is developed. Neutral particles sprayed out in all directions from the earth's atmosphere are ionized at 50,000 to 70,000 km levels by the ultra-violet light of the sun. Because of the wabble of the earth's magnetic field with the rotation of the earth ions near the equator...
Article
Assuming that the atmosphere at the surface of Mars consists of ⅕ oxygen and ⅘ other gases, as nitrogen, etc., the composition of the atmosphere to great heights is calculated, just as was done for the earth, from the actions of gas diffusion and gravity. The electron density in the atmosphere of Mars due to the ultraviolet light of the sun is foun...
Article
Measurements between two stations 0.4 km apart with a thermocouple and galvanometer and with spectrograms, properly calibrated, of the absorption of light by fog for wave-lengths from 0.4 to 3mu showed that the absorption increased slightly with decrease in wave-length, but hardly enough to indicate that red light is appreciably better than blue li...
Article
DOI:https://doi.org/10.1103/PhysRev.34.1063
Article
DOI:https://doi.org/10.1103/PhysRev.34.161
Article
A recent theory of the authors attributed terrestrial magnetic storms and auroral displays to the effect of unusual flares of ultra-violet light from the sun falling upon the terrestrial atmosphere. Such flares would be expected to cause changes in comets, and therefore comet changes should be closely connected with magnetic storms. This connection...
Article
The ultra-violet light theory of aurorae and magnetic storms suggests (1) that because of winds and unusual production of ions the ionized region of the high atmosphere may be in violent agitation during the day of a magnetic storm, that it grows calmer at night and becomes agitated the next day if the storm continues, (2) that there may be auroral...
Article
Measurements were made with a quartz mercury lamp, a quartz spectrograph and a recording densitometer of the attenuation of ultra-violet light from 3000 to 2050A by the atmosphere at sea level. For wave-lengths from 5000 to 3000A the absorption was too slight to be observed at distances up to 400 meters; for wave-lengths below 2800A there was prono...
Article
It is assumed that the ionization in the upper atmosphere is caused by the ultra-violet light of the sun and that the ion and electron densities at noon at the equator are in keeping with the facts of wireless waves. From the laws of recombination of the ions and of diffusion and drift of the ions in the earth's magnetic, gravitational and electric...
Article
A theoretical investigation has been made of the outlying regions of the atmosphere of the Earth and of the effect of sunlight on these regions; certain of the conclusions are given in this preliminary note. By the usual methods the temperatures and the pressures of the atmosphere to great heights were calculated for a quiet Sun, that is for the Su...
Article
With a quartz spectrograph, sodium hydride quartz photoelectric cell and quadrant electrometer, measurements were made in the ultraviolet spectrum region λ4000 to 2500A of the light absorption coefficients of pure water and sea water and of the molecular absorption coefficients of aqueous solutions of the principle salts in the sea, namely, NaCl, K...
Article
A theory of the ionization of the upper atmosphere of the earth by the ultra-violet light of the sun is developed based on known laws of pressures and constitution of the high atmosphere, ionic recombination, attachment of free electrons to neutral molecules, and diffusion of ions. It is concluded that the solar ultra-violet light is a necessary an...
Article
Number of quanta emitted per atom.—The total radiation, measured with a thermocouple, in the spectral region 6000 to 2300A from a small quartz mercury lamp of known size filled with mercury vapor at a known pressure was 1.85×10−10 ergs per atom per sec. From this and the intensities of the lines it came out that each atom on the average emitted eac...
Article
DOI:https://doi.org/10.1103/PhysRev.32.996
Article
Recent measurements have shown that radio waves below 150 meters fall off in intensity faster than required by an inverse square law for distances up to 1000 miles. This points to absorption of the wave by the medium, in this case the upper atmosphere. The absorption of the waves variously polarized is calculated on the assumption that it results f...
Article
Temperature and percentage dissociation of He, H2, O2, N2, air, CO and CO2 as functions of pressure and power input in discharge tubes.-The increase in pressure of a gas in a discharge tube due to the discharge has been measured for pressures from about 0.1 to 20 mm of mercury for helium, hydrogen, oxygen, nitrogen, air, carbon monoxide and carbon...
Article
THE more important agencies which may conceivably cause the ionisation of the upper atmosphere of the earth are the ultra-violet light, alpha- and beta-particles, all of solar origin, the penetrating radiation of cosmic origin, and the ionising radiations from terrestrial sources. The last mentioned may perhaps be ruled out immediately because of t...
Article
About 90% of the energy radiated from a long hydrogen tube filled with moist hydrogen at a pressure of 0.54 mm of mercury and absorbing 400 watts was found to be carried by the first three lines of the Balmer series. From the measured values of this energy and of the relative intensities of Halpha, Hbeta and Hgamma, the number of quanta of these li...
Article
Measurements of the absorption of ocean water for monochromatic light throughout the visible spectrum are recorded and show that the sea water is about as transparent as pure water. When daylight is passed through 40 meters of water the resulting spectral intensity curve is very similar to the visibility curve of the eye both as regards shape and t...
Article
Theoretical deflection of a beam of electrons by electromagnetic radiation.- Assuming (a) the theorems of conservation of energy and momentum and (b) the agreement of the light quantum theory with the wave theory in their estimates of the radiant energy scattered in various directions from a beam of electromagnetic radiation by a group of electrons...
Article
Laboratory method of obtaining ten Balmer lines in absorption.-Condensed discharges were passed through an under water spark in series with a tube, 75 cm in length, of moist hydrogen at a pressure of 0.5 mm of mercury. The light from the spark traversed the glowing hydrogen, and the Balmer lines appeared as narrow dark absorption lines against the...
Article
An enforceable Comprehensive Nuclear-Test-Ban Treaty (CTBT) regime will require accurate detection and location of low-yield (1 kT or less) nuclear detonations. For reliable infrasonic detection and location of candidate events, a thorough knowledge of the upper atmosphere and advanced modeling techniques is required. Currently, a near-real-time gl...
Article
Theory of radio wave propagation over the earth.—Larmor's theory of refraction due to the electrons of the Kennelly-Heaviside layer does not explain the "skip distances" for short radio waves (regions of silence around the transmitter which Taylor's measurements showed to be 175, 400, 700 and 1300 miles in radius in the daytime for waves of 40, 32,...
Article
It has been assumed by Birkland, Strömer, Vegard and others that the aurora is caused by charged particles from the sun which are diverted to the polar regions by the magnetic field of the earth. There are possible objections to this and it is suggested that the aurora is due to ultra-violet light of the sun which produces ions and electrons in the...
Article
Ionospheric variability creates many practical problems that motivate efforts toward better forecasting and monitoring. At the same time it presents challenging plasma physics problems having to do with issues such as the development and propagation of irregularities. Ultraviolet remote sensing is among the best means of obtaining the required diag...
Article
The paper describes a small, rugged, portable, quick period wind meter for measuring the speed of wind and of gusts of wind. The instrument consists essentially of a mica vane and pointer twisting a torsion wire.
Article
Cosmic-ray nuclei that enter the atmosphere will subsequently breakup into lighter nuclei due to collisions with air particles. They also undergo a gradual loss of energy due to ionization. The fluxes and energy spectra of particles were calculated for several atmospheric depths and geomagnetic locations. The results of these radiation transport ca...
Article
The physics of the atmosphere of the earth under a quiet sun is discussed in detail. The daytime temperatures above 100 km increase with the height to roughly 1000°K at a 400 km level; new tables of the molecular density of the atmosphere to great heights are given. In the region above 450 km, where the molecular free paths are very long, a portion...
Article
The outer atmosphere of the sun is assumed to be composed mainly of ions and electrons which are actuated by gravitation, radiation pressure and the magnetic field of the sun. By distillation along the lines of magnetic force the particles collect in the lower latitudes of the solar outer atmosphere and by their diamagnetism reduce the magnetic fie...
Article
Effect of the source on the continuous spectrum of hydrogen—The continuous spectrum of hydrogen is observed to be of similar character, although of differing intensity, in a number of sources, a Wood tube, an ordinary discharge tube, the separate striations of the positive column, the condensed spark in hydrogen at pressures above atmospheric, and...
Article
The technique of sputtering is described. Opaque, optically good films were sputtered in a residual atmosphere of air from cathodes of Sb, Bi, Cd, Au, Pb, Pt, Ag, Sn and Zn in about an hour; from Co, Cu, Ir, Fe, Ni, Se and Te in two hours or so; and from Mo, Ta and W in several hours. Al, Be, C, Cr, Mg and Si sputter very slowly in air. In a residu...

Citations

... For this calculation densities used are those of the Rocket Panel (cf. Newell 1960 , Table II). ...
... [92] The causal connection between solar phenomena and terrestrial magnetic storms was finally established in 1905 by British astronomer Edward Maunder, on the basis of a 27-day recurrence of magnetic storms correlated with the sun's 27-day rotation period [109]. Even still, an ultraviolet light theory of magnetic storms proposed in 1929 asserted that solar flares were no more than a burst of ultraviolet radiation that excited and ionized atoms in the upper atmosphere [108]. ...
... Around the same time, Faraday developed the concept of lines of force to give a direct, physical description of electromagnetic phenomena [2]. By the turn of the 20th century "tangles" or knots in solar currents were already being observed and could be explained by magnetic effects [3,4]. Since then, the topological properties of lines of force, such as their linking, knotting, twisting, and kinking, have been studied in many physical systems [5,6]. ...
... Instead of s and p is now used Greek letters σ and π respectively in marking of orbitals [10,11]. ...
... Hulburt and Taylor even worked together on such engineering issues as the skip distance, i.e. the shortest distance permitting radio signals to travel from the transmitter to the receiver by ionospheric reflection. In 1926, their alliance culminated in a theory to determine the density of free electrons in the ionosphere (Taylor and Hulburt, 1926). By 1928, the gap was conspicuous between a division that contributed to the physical theory of the ionosphere and the Radio Division, with its massive collection of data on signal strength and transmission ranges at various frequencies. ...
... EPDs often occur in the ionospheric F 2 layer after sunset. The RTI is generally accepted to be the possible mechanism to trigger it (Dungey, 1956;Johnson & Hulburt, 1950;Kelley, 2009). After sunset, the ionization density at ionospheric E region decays fast, due to the absence of sunlight after sunset. ...
... By the 1930s sputter deposition of thin films had found commercial applications (Fruth, 1932). Early on sputter deposition was based on cathode sputtering or dc diode sputtering (Hulburt, 1934). However, in the 1950s sputter deposition of thin films had been almost completely replaced by thermal evaporation (Holland, 1956). ...
... For higher RH level, N 2 carrier gas was bubbled through water and the humidity level inside the test chamber was continuously monitored with a Tinytag Plus 2 temperature and humidity data logger. At higher RH level, we noticed that the sensitivity of the nanorod coated fiber sensor drops significantly due to the higher visible light absorption coefficient of the water molecules (in the order of 10 −2 m −1 ) adsorbed on the surface of the ZnO nanorods than the air (in the order of 10 −4 m −1 ) [22]. Sensitivity was found to drop from 21.5% to 10.9% for the nanorod coated fiber sensors when the RH level was raised from 15% to 50%, which was observed to further reduce to 7.7% at 80% RH level, indicating that the sensing environment conditions are crucial for the proposed ZnO nanorod coated fiber sensors. ...
... The rift was due in part to the successful solving of the problem of skip distance -Hulburt and Taylor had modified Joseph Larmor and Eccles' ionic refraction theory. But it owed more, especially in the 1930s, to the formulation of Hulburt's theory that postulated the action of solar ultraviolet radiation as the causal agent for atmospheric ionisation (Hulburt, 1928(Hulburt, , 1938. The success of his ideas is reflected in the NRL's reorientation towards basic research and innovation. ...