Luminous Column Research Articles

Orbital Characterization of Superbolides Observed from Space: Dynamical Association with Near-Earth Objects, Meteoroid Streams, and Identification of Hyperbolic Meteoroids

There is an unceasing incoming flux of extraterrestrial materials reaching the Earth atmosphere. Some of these objects produce luminous columns when they ablate during the hypersonic encounter with air molecules. A few fireballs occur each year bright enough to be detected from space. The source of these events is still a matter of debate, but it is generally accepted that they are of sporadic origin. We studied the NASA-JPL Center for NEOs Studies (CNEOS) fireball database to infer the dynamic origin of large bolides produced by meter-sized projectiles that impacted our planet. These likely meteorite-dropping events were recorded by the US Government satellite sensors. We estimated the false-positive rate and analyzed the time evolution of multiple orbit dissimilarity criteria concerning potential associations with near-Earth objects and meteoroid streams. We found that at least 16% of the large bolides could be associated with meteoroid streams, about 4% are likely associated with near-Earth asteroids, and 4% may be linked to near-Earth comets. This implies that a significant fraction of meter-sized impactors producing large bolides may have an asteroidal or cometary origin. In addition, we found at least three bolides having hyperbolic orbits with high tensile strength values. Meter-sized meteoroids of interstellar origin could be more common than previously thought, representing about 1% of the flux of large bolides. The inferred bulk physical properties suggest that the interstellar medium could bias these projectiles toward high strength rocks with the ability to survive prolonged exposure to the harsh interstellar space conditions.

Imaging of Discharge Plasma Channel Evolution Process of Microsecond Wire Explosion in Air

The discharge plasma channel (DPC) evolution process is observed by taking time-series self-emission intensified charge-coupled device (iCCD) photos and simultaneous shadow images. By adding neutral density filters before iCCD, the subtle structure of the DPC self-emission is observed. It is interesting that a treelike structure is observed soon after the voltage breakdown. Long exposure time photos demonstrate that this structure existed for hundreds of nanoseconds. An inner homogeneously luminous column arises latterly, forming a two-layer self-emission structure. Then, this column gradually occupies the whole DPC. Shadow images show that the expanding DPC maintains good axial uniformity, manifesting the long-standing uneven treelike structure only has limited impact on the energy distribution and the expansion process. The calculated expansion rate reaches its maximum value (4.75 km/s) not at the power peak, but 0.24 $\mu \text{s}$ after that. Then, the expansion rate undergoes fast drop and slow decline. In addition, it seems that the distributions of related plasma parameters experience an evolution from nonuniform to uniform.

Illumination of mesospheric irregularity by lightning discharge

Theoretical model calculations recently predicted the existence of mesospheric irregularities which assist the initiation of sprites. Here we report the experimental detection of a ∼3–19 km3 large mesospheric irregularity at ∼80–85 km height which is illuminated by the electromagnetic field of an intense positive cloud‐to‐ground lightning discharge. While the lightning discharge causes a prompt group of four sprites above the lightning discharge, the mesospheric irregularity is found at a horizontal distance at least ∼15–20 km away from the sprite group and it rebrightens ∼40–60 ms after the sprite group occurrence. This rebrightening is driven by a local quasi‐static electric field enhancement with a charge moment ∼4–20 Ckm which causes the irregularity to develop a downward descending luminous column from ∼75–85 km height. The quasi‐static electric field enhancement is caused by the reorganization of residual charge inside the thundercloud during a high‐level activity of intracloud discharges with ∼10–20 pulses per ms. Such mesospheric irregularities might have an effect on the wave propagation of 100 kHz radio waves which are used for atomic time transfer and marine navigation.

Characteristics and generation of secondary jets and secondary gigantic jets

Secondary transient luminous events (TLEs) recorded by the ISUAL‐FORMOSAT2 mission can either be secondary jets or secondary gigantic jets (GJs), depending on their terminal altitudes. The secondary jets emerge from the cloud top beneath the preceding sprites and extend upward to the base of the sprites at ∼50 km. The secondary jets likely are negative electric discharges with vertically straight luminous columns, morphologically resembling the trailing jet of the type‐I GJs. The number of luminous columns in a secondary jet seems to be affected by the size of the effective capacitor plate formed near the base of the preceding sprites and the charge distribution left behind by the sprite‐inducing positive cloud‐to‐ground discharges. The secondary GJs originate from the cloud top under the shielding area of the preceding sprites, and develop upward to reach the lower ionosphere at ∼90 km. The observed morphology of the secondary GJs can either be the curvy shifted secondary GJs extending outside the region occupied by the preceding sprites or the straight pop‐through secondary GJs developing through the center of the preceding circular sprites. A key factor in determining the terminal height of the secondary TLEs appears to be the local ionosphere boundary height that established by the preceding sprites. The abundance and the distribution of the negative charge in the thundercloud following the sprite‐inducing positive cloud‐to‐ground discharges may play important role in the generation of the secondary TLEs.

Anode Discharge Electrolysis of Molten LiCl-KCl System

Anode discharge electrolysis has been conducted with a molten LiCl-KCl system under 1 atm of Ar or at 723 K. By applying a 500 V dc voltage, a discharge was generated between the melt and the anode whose tip was positioned above the bath surface. The discharge was found to be stable, and the current density of the luminous column was estimated to be about 100 A cm−2. In order to investigate the discharge characteristics, cell voltage was measured at various conditions. From the estimated current density and the variations of cell voltage, this anode discharge was considered to be a kind of arc discharge. The charge-transfer process between anode and melt during anode discharge electrolysis was also investigated. When a titanium or an iron wire was used as the anode, redox peaks corresponding to a Ti(II)/Ti or an Fe(II)/Fe couple were observed by cyclic voltammetry in the melt after anode discharge electrolysis. Since there was no titanium or iron source in the experimental apparatus except for the anode, it was indicated that cation emission from the anode is involved in the charge-transfer process. The estimated ionization current efficiency was dependent on the anode materials. © 2002 The Electrochemical Society. All rights reserved.

Velocity Measurement in Hypersonic Flows Using Electron-Beam-Assisted Glow Discharge

A new pseudospark-type electron gun has been utilized in the F4 high-enthalpy, low-density, hot-shot wind tunnel at ONERA. The main goal was to perform accurate measurements of the velocity profile across the boundary layer and the freestream through a time-of-flight principle. In these experiments, an intense pulsed electron beam traces the path of a high-voltage, sustained-glow discharge in some 10 ns. A charge-coupled device camera is opened briefly, 5 μs after the electron gun actuation, to image the position of the luminous column convected by the flow

Decay of a vertical plasma column: A model to explain VLF sprites

VLF sprites are identified by high angle scattering of VLF transmissions by the conducting plasma columns which appear as the luminous columns of “red sprites”. VLF sprites are “early/fast Trimpis” and probably vice versa. Recently discovered properties of early/fast Trimpis are the logarithmic decay of the amplitude of the scattered signal and monotonic variation of its phase. These properties are explained in terms of scattering from a vertical column or set of columns extending from 50 km (or lower) altitude to about 80 km.

Comment of “VLF signatures of ionospheric disturbances associated with sprites” by Inan et al.

The events described by Inan et al. [1995b] in the paper under comment here, and earlier as “VLF sprites” [ Inan et al., 1995a], refer to VLF scattering confined to a very narrow range about the forward direction. This must be produced by horizontally extensive (few hundred km) ionospheric disturbances with a Gaussian shape as suggested by them. Such scattering is quite at odds with the very wide angle VLF scattering (even to 180°) observed by Dowden et al. [1995]. The reason for this is not due to differences in receiving equipment or data interpretation, but due to the scattering sources being quite different in size and shape. The narrow angle scattering sources may be the recently discovered “elves” (Emissions of Light and VLF perturbations from EMP) produced by the electromagnetic pulse (EMP) of lightning. The wide angle scattering sources have been identified as the thin (∼ 1 km) vertical columns of plasma as predicted by Dowden et al. [1994] and seen as the luminous columns of sprites.

Sprites as luminous columns of ionization produced by quasi‐electrostatic thundercloud fields

Quasi‐electrostatic (QE) fields which exist above thunderclouds after lightning discharges can lead to the formation of columnar channels of breakdown ionization and carrot‐like vertical luminous structures with typical transverse dimension ∼5–10 km spaning an altitude range from ∼80 km to well below ∼50 km. The carrot‐like forms closely resemble those observed in sprites. Results indicate that the appearance of optical emissions can be significantly delayed in time (∼1–20 ms) with respect to the causative lightning discharge.

A New Play by Apollinaire

A New Play By Apollinaire Willard Bohn In July 1914, Guillaume Apollinaire, who was at that time the leader of the Parisian avant-garde, composed an important pantomime in collaboration with three other artists: A quelle heure un train partira-t-il pour Paris? (What Time Does A Train Leave For Paris?). The only copy of this work known to exist was recently discovered by the present author in a private library in the United States.1 Modeled on a 1913 poem by Apollinaire, “The Musician of Saint Merry,”2 the pantomime featured a scenario by Apollinaire, “music by Alberto Savinio, sets and staging by Francis Picabia and Marius de Zayas” according to the title page. Unfortunately, no contributions by the latter three individuals have been discovered—if indeed these ever existed. For the outbreak of World War I one month later prevented the collaborators from going ahead with their plans to electrify the avant-garde with their revolutionary new work. In 1917, concurrent with the production of The Breasts of Tiresias, Apollinaire apparently attempted to revive his original project as a ballet, but his death in 1918 effectively relegated this project to oblivion.3 While the 1914 scenario is ostensibly Apollinaire’s independent creation, it is readily apparent that his fellow collaborators contributed various ideas that helped to determine the eventual shape of the pantomime. Analysis of influential currents and cross-currents reveals, as we will see, that Apollinaire was indebted to the Italian Futurists as well. The plot of What Time Does A Train Leave For Paris? is deceptively simple. On the whole it follows that of the original poem quite closely, except for the final scene which was in­ vented specifically for the pantomime. With the exception of this scene, the major innovations are limited to stage effects and costumes. Scene 1. A poet stands before a luminous screen occupying the entire stage. As a number of silhouettes pass across the 73 74 Comparative Drama screen, he greets each one with a brief, jerky, automatic ges­ ture, thus dramatizing the first line of the poem (“At last I have the right to greet beings whom I do not know”). Then a curtain descends to cover the screen, and a powerful voice cries through a megaphone: I sing not of this world nor of other stars I sing all the possibilities of myself beyond this world and the stars I sing the joy of wandering astray and the pleasure of dying thereby. This is the second stanza of the poem. Scene 2. A strip of cloth passes across the curtain with the date specified in the poem: May 21, 1913. The curtain rises to reveal millions of flies flying around a luminous column—a symbol of Beelzebub. The lights dim, then come back up to reveal sets representing a rooftop view of Paris: rooftops, smoking chimneys, the Eiffel Tower, the Arc de Triomphe, Notre Dame, and a Tall Factory Chimney. A hand printed on the wall indicates a placard reading “rue Aubry-le-Boucher.” Then a man with no eyes, no nose, and no ears enters, crosses the stage, and disappears into the street. The Eiffel Tower pro­ jects slides or movies into the audience, accompanied by sounds evoking modem city life and by various shouted phrases, e.g., “When I was a child there were no automobiles” and “Help!— An airplane is buzzing us.” Scene 3. A small square with a fountain. In the background stand the three monuments and the Tall Factory Chimney seen previously. The faceless man slowly crosses the stage, playing a flute, and stops before the fountain. All sorts of women crowd around him, wild-eyed, their arms stretched out before them. These include a “headless woman, an armless woman, a blue woman, a red woman, a bald woman, a smartly dressed woman, a little girl, an old lady, some good-looking whores, women with flowing tresses, nude women.” The faceless man ceases playing, drinks from the fountain, resumes playing, and retraces his steps—followed by the women . Scene 4. Slides and/or movies present a survey of life and its variety: European urban and country life, trains, tropical flora and fauna, the...

Study of laser-supported detonation waves by time-resolved spectroscopy

Temporal developments of sparks generated by a pulse CO2 laser from solid surfaces in air have been studied by time-resolved spectroscopy in the range from 3800 to 6200 Å. The plasma front appears to be a detonation wave during the early part of the pulse when the laser intensity exceeds about 2 × 107 W/cm2. With decreasing laser intensity, the plasma which contains N+ and O+, expands both forwards and backwards to become a luminous column in a way similar to the combustion wave described by Raizer. Stimulated emission from AlO has been observed in the vapor from an alumina sample.

Measurement of an Electron Density Disturbance in a Positive Column with Magnetic Field

Abstract It is found that two columns of different luminosity which are separated by an intervened disc appear along a magnetic field, when a certain disc is inserted in a positive column with an axial magnetic field. These are a luminous column and a dark column which are extended from the disc toward the cathode and the anode side respectively. These deviations in luminosity decay from it in the direction of each side. Change in luminosity along the axis is confirmed by measurements of electron density distribution with movable probes. An attempt to attribute this recovery toward the normal distribution to ambipolar diffusion of charged particles across the magnetic field is given.

Production of x-rays during a low-pressure gas discharge

The impulse breakdown of several gases at pressures of a few microns of mercury has been investigated. During the first stage of the discharge, a microsecond burst of X-rays is emitted from a spot of about 8 mm diameter on the anode electrode. If the initial voltage applied to the tube is 600 kV, a single X-ray pulse will produce a legible radiograph through about 5 cm of steel. The mechanism of the discharge has been studied and high-speed photographs of the visible discharge show a luminous column moving from cathode to anode. Steenbeck's theory(3) has been extended to show qualitatively the probable sequence of events during the discharge.

Striations in High Frequency Discharges

IN the course of an investigation on the starting and maintenance potentials of the luminous column in argon, produced by applying a high frequency potential of wave-length from 10 to 300 metres to external sleeve electrodes, we found that steady striations were frequently developed. Using the method described by Townsend and Donaldson (Phil. Mag., January 1928), an attempt was made to measure the potential fall over single striations to see whether any definite value could be assigned to it.

La materia radiante e i raggi magnetici

IN a recent number of NATURE a brief account was given of Righi's “magnetic rays,” this being the name applied to a peculiar luminosity near the kathode of a vacuum tube, when the latter is placed in a longitudinal magnetic field. Righi supposes that this luminous column is due to electrically neutral doublets, which are not in sufficiently stable equilibrium to be looked upon as atoms or molecules, which owe, in fact, such stability as they possess to the action of the magnetic field. Several papers on this subject have been published by the author, and the main object of the present small volume is to give a connected account of the whole research. About one-third of the book is devoted to an extremely lucid and interesting summary of our present knowledge concerning the corpuscular theory of matter, written in a style which, as far as possible, is free from technical terms. The remainder, except for three short mathematical appendices, deals with the evidence for and against the existence of neutral doublets or magnetic rays. Here, while very suggestive, the experiments are not altogether convincing—this is evidently the opinion of Prof. Righi himself—but this is due in great measure to the difficult experimental conditions. While no one experiment can be said to have demonstrated the existence of magnetic rays, the results as a whole certainly tend to support the author's view. One point might have been treated more fully, viz., the conditions under which a magnetic field lowers the potential difference at the terminals of the discharge tube. Experiments are described, in some of which an increase, in others a decrease, of potential is brought about by the magnetic field, but it is not clear to what difference in the conditions this is due. La materia radiante e i raggi magnetici. By Prof. A. Righi. Pp. vii + 308. (Bologna: N. Zanichelli, 1909.) Price 8 lire.

An investigation of the influence of electric fields on spectral lines: preliminary note

In general the electrical fields used were those concomitant with the luminous electric discharge. An interferometer of the Michelson form and an echelon spectroscope of 18 plates were used to analyse the radiations. The results may be summarised as follows:— (1) End-on discharge tubes of special design, in which the light-source was a uniform column of luminous mercury vapour viewed in the direction of discharge, showed no change of wave-length as great as 1 part in 4,000,000 when the direction of the discharge was reversed. The pressure in the tube was varied from a few millimetres to a vacuum so high that there was but little luminosity. (2) The passage of Röntgen rays through the tube did not alter the wave-length nor the width of the mercury lines, to an extent sufficient to affect the visibility of interference fringes formed with a difference of path of 400,000 waves. When the luminous column was viewed at right angles to the direction of the discharge no polarisation effects in the radiation from it, due to the passage of the Röntgen rays, could be detected by a sensitive Savart plate and Nicol prism.

Societies and Academies

PARIS Academy of Sciences, August 23.—M. Wurtz in the chair. -The following papers were read:—Meridian observations of small planets at the Greenwich and Paris observatories during the second quarter of 1880, communicated by M. Mouchez.— Distinctive character of the pulsation of the heart, according as the right or left ventricle is examined, by M. Marey. During a stoppage in respiration the right heart shows a diminution in amplitude of pulsations, owing to pulmonary resistance, while the left heart shows a slight increase. If through any influence lowering the arterial tension (such as muscular exercise, inhalation of nitrite of amyl, &c), waves be produced in the aorta, these waves cause in the tracing of pressure of the left ventricle a bifurcation or trifurcation of the summit (according as two or three have occurred during systole). The right ventricle does not show these waves, unless in vestige, and by propagation from the neighbouring part.—Remarkable example of vertically-ascending lightning, by M. Trecul. This was during a storm on Aug. 19. The sparks appeared to come from some lightning conductors in the place. Some rose singly and disappeared at a small height, expanding into a magnificent, nearly circular flash, the light of which diminished from centre to circumference. In one case two luminous columns rose simultaneously and parallel, and at a certain height precipitated themselves against each other at a right angle.—The death of M. Godron, correspondent in botany, was announced.—The sun would act inductively on the earth even if its magnetic power were simply equal to that of our globe. Induction of the moon by the earth and diurnal lunar variation of terrestrial needles, by M. Quet. The induction of the earth by the sun could be insensible only if the magnetic power of the latter were much below that of the former, which is not probable. The induction of the moon due to its revolution round the earth produces an electromotive force twenty-one times less than that the effects of which are rendered sensible by an experiment made on the earth, and consequently is itself sensible. As the induction of the satellite by rotation of the earth is about twenty-seven times greater than the foregoing, the resultant will be a sensible force with sensible reaction on particular earth-currents, leading to a daily variation of needles according to lunar hours.— On the variations of the coefficient of dilatation of glass, by M. Crafts.—On tungstoboric acid, by M. Klein.—On the products of distillation of colophony, by M. Renard.—On the project of establishment of a station for hospitable purposes at the sources of the Ogooue, by the French Committee of the African Association, by M. Mizon.

VI. On the sensitive state of electrical discharges through rarefied gases

It has frequently been remarked that the luminous column produced by electric discharges in vacuum-tubes occasionally displays great sensitiveness on the approach of a finger or other conductor to the tube. The exact effect of such approach varies considerably with the circumstances of the discharge. In many instances the luminous column is repelled; in others, and especially when the finger is brought into actual contact with the glass, the column is severed; and in the latter case, in addition to the luminosity previously present, there often appears proceeding from the interior of the tube, at the point where the finger rests, the blue haze which usually characterises the negative end of a discharge. In some cases the discharge is so powerfully affected that the well-known green or blue fluorescence appears on the side of the tube opposite to the point touched. The degree of sensitiveness varies between wide limits. Discharges frequently occur in which close observation is necessary to detect any trace of it, while others may be produced so sensitive that the magnetic action of a powerful electro-magnet is hardly more marked than the action which is due to it as a conductor. The condition in question does not appear to be confined to any particular gaseous medium or to any special form of tube; and it is in fact probable that in almost any tube sensitiveness may be produced by adopting suitable precautions. This state of sensitiveness may be exhibited by stratified discharges, but it is more commonly associated with those which show no clear traces of stratification. It is not however universally present in either kind of discharge.

I. On the sensitive state of electrical discharges through rarefied gases

It has frequently been remarked that the luminous column produced by electric discharges in vacuum tubes sometimes displays great sensitiveness on the approach of the finger, or other conductor, to the tube. This is notably the case when with an induction coil a very rapid break is used, or when with any constant source of electricity an air-spark is interposed in the circuit leading to the tube. The striking character of the phenomena, and the opportunity which they showed for affecting the discharge from the outside during its passage, led the authors of this paper to consider that a special examination of this sensitive state would be desirable.

1. An account of a remarkable aurora borealis seen at Montreal on the 13th of August 1849

The author having witnessed a singular aurora on the 13th of August, in this communication gives a description of the phænomenon. He states that, on the evening in question, the whole northern hemisphere was screened by thick dark clouds, which, though very small, were closely packed together. Shortly after sunset (7 h 34 m ) it became quite dark, and at 8 o’clock the existence of the meteor was indicated by a mellow luminous tinge which appeared through the openings of the clouds in the north. About half-past eight a similar luminous glow was observed through the clouds which were fast disappearing in a heavy dew. This light appeared like a belt of 2° broad, extending across the sky from a point almost due east directly to the west, and reaching within 5° or 6° of the horizon. As the clouds disappeared, which they did very rapidly, the true character of the aurora became more perfectly developed. In the north the usual dark arch from which the columns of light ordinarily appear to issue, was for the greater part of the time wanting; and the luminous columns seemed to rise from the earth, extending upwards occasionally to the pole star, beyond which no trace of them was visible. A brown vapoury cloud, the only one now visible, extended along the horizon from N. N. E. to a few points south of east, and maintained apparently a motionless position, the lower part appearing to rest upon the earth, and the upper edges, which seemed uniform, rose about 6° above the horizon. Immediately in the east, and apparently issuing from this cloud, rose the belt or zone of light already noticed, forming a magnificent arch. The light emitted from this zone was of a milky whiteness, and the matter of it seemed to be much more compact than any portion of an aurora ever seen by the author; but immediately in the zenith, where it intersected the Milky Way, it appeared to be far less compact. At this point, where alone motion was observable, a constant current was seen, presenting the appearance of light fleecy clouds driven by a strong wind, and following each other in such close succession as to appear in contact. This stream of the aurora was maintained undiminished for more than an hour, during which time the eastern part of the zone did not appear to lose either in volume or brilliancy, nor did the western seem to gain in either of these respects. After an hour, the dark cloud seemed to diminish slowly, and with it the zone began to lose its brilliancy. In about another hour this cloud and also the zone, which throughout had maintained apparent contact with it, vanished. The conclusion, that the dark cloud served the purpose of a conductor and fed the zone drawing off the matter of the aurora from the north, seemed to the author inevitable. The cloud did not appear to him to be more than forty or fifty miles distant. In conclusion he remarks that none of the prismatic tints were observable on this occasion.