scholarly journals On the excitation of the band spectrum of helium

1925 ◽  
Vol 109 (750) ◽  
pp. 267-272 ◽  
Keyword(s):  
Discharge Tube ◽  
High Current Density ◽  
Band Spectrum ◽  
Essential Condition ◽  
Spark Gap ◽  
In Series ◽  
Pure Helium ◽  
Faint Band ◽  
The Individual ◽  
Low Pressures

It is now generally agreed that the band spectrum of helium, which was first observed by Curtis (‘Roy. Soc. Proc.,’ A, vol. 89, p. 146, 1913) and by Goldstein (‘Verh. d. Deutsch. Phys. Gesell.,’ vol. 15, p. 402, 1913), is to be attributed to some molecule of helium. This band spectrum is peculiar in the fact that the heads of the bands have been shown by Fowler (‘Rov. Soc. Proc.,’ A, vol. 91, p. 208, 1915) to follow the law usually associated with line spectra, though the individual lines composing the bands can be represented by the parabolic arrangement appropriate to band series. More recently, Curtis has carried out a series of investigations (‘Roy. Soc. Proc.’) on the structure of the bands in terms of the quantum theory. Attention may here be drawn to two peculiarities in the spectrum. There is one isolated band with a head at about λ = 5733 A., which is degraded to the violet, whilst all the remaining bands are degraded to the red. Also Goldstein ( loc. cit. ) observed a number of faint band lines in the region about λ = 5390 A. to λ = 5270 A., which were not recorded in Curtis’s paper ( loc. cit .). It is well known that in vacuum tubes excited by uncondensed discharges only faint traces of the principal band heads are visible in the positive column though the complete band spectrum appears in the negative glow. The band spectrum can be excited with much greater intrinsic brightness by using a discharge tube with a wide tube in place of the usual capillary, and exciting it by means of a discharge from an induction coil or transformer, with a condenser in parallel and a small spark gap in series with the discharge tube, the band spectrum under these conditions appearing throughout the tube. There appears to be an optimum length of spark gap and the spectrum tends to become weaker when the length is increased beyond a certain point. Curtis ( loc. cit .) has found that the band spectrum is not strongly developed at low pressures, and this condition appears to be independent of other conditions of excitation. In the present investigation we have found that under certain conditions the band spectrum can be greatly modified. It was observed that when a vacuum tube, containing pure helium, which had been made with the capillary in several sections of different bore, was excited with an uncondensed discharge the narrowest section, which was of the finest thermometer tubing that could be worked conveniently in the blowpipe, showed nothing but the line spectrum, but in the wider sections on either side the band spectrum was quite strongly developed. This seems to show that a high-current density is not an essential condition for the excitation of the band spectrum, but it was remarkable that with these tubes it appeared in the wider parts, where it would not have been seen if the capillaries had not been provided with a section of narrow bore.

scholarly journals IV. On the nature of the streamers in the electric spark

1909 ◽  
Vol 209 (441-458) ◽  
pp. 71-87 ◽  
Keyword(s):  
Incident Light ◽  
Close Relation ◽  
Actual Process ◽  
Metal Vapour ◽  
New Era ◽  
Spark Gap ◽  
In Series ◽  
The Subject ◽  
The Doppler Effect ◽  
The Individual

When the oscillating electric spark is examined in a rapidly rotating mirror, the successive oscillations render themselves evident in the image as a series of lumnious curved streamers which emanate from the poles and extend towards the centre of the spark gap. These streamers were first observed by Feddersen in 1862, but the work of Schuster and Hemsalech in 1900 may be said to have opened up a new era in the subject. These workers threw the image of the spark on the slit of a spectroscope, and photographed the resulting spectrum on a film which was maintained in rapid rotation in a direction at right angles to that of the incident light. In their photographs they found that the air lines extended straight across from pole to pole, but that the metal lines were represented by curved bands drawn out in the centre of the spark gap. There is a close relation between these bands and the streamers seen in the unanalysed inductive spark. Schuster and Hemsalech carried out their experiments with the smallest possible inductance in series with the spark, and thus made the period of the oscillations so small that the drawing out on the film was insufficient to separate the individual oscillations from each other. Thus their curved lines represent a composite structure, consisting of all the streamers due to the successive oscillations superposed on each other. It follows from their results that the light of the streamers in the spark is entirely produced by the glowing of the metallic vapour of the electrodes, and that, while the luminosity of the air is practically instantaneous in its occurrence, that due to the metal vapour occurs in the centre of the spark gap an appreciable time later than near the poles. The actual process which goes on in the spark and gives rise to this delay in the arrival of the metallic vapour at the centre of the gap is not yet thoroughly understood. Schuster and Hemsalech make the natural supposition that it is due to the fact that the metal of the electrode is vaporised and rendered incandescent by the heat of the spark, and that the vapour takes an appreciable time to diffuse from the electrodes to the centre of the gap. The exception which has been taken to this view has arisen in part from the difficulty of observing the Doppler effect on the metallic lines which should be a concomitant of the diffusion of the vapour from the poles, and in part from the extraordinary results which the authors themselves obtained in some metals for the velocity of the diffusion corresponding to the different lines. In the case of bismuth and, in a less degree, of cadmium the different metallic lines could be divided into groups of different curvatures which indicated different velocities of diffusion towards the centre of the gap. As regards the former matter, there does not seem to be involved any real difficulty to the explanation, as Dr. Schuster has himself recently shown. The curious effect of the different curvatures of the lines of the same element has, however, always remained more or less of a difficulty in the way of a complete acceptance of their view. Schuster and Hemsalech themselves refer to the possibility in the case of bismuth that the metal may be a compound, and that the two kinds of molecules give rise to the differently curved lines. Other explanations have been made by different writers, but it cannot be said that any explanation adequately supported by experiment has been forthcoming. In view of this incompleteness in our knowledge of the constitution of the streamers it seemed to me that further observations with a rotating mirror would possibly be of value, and the investigations recorded below succeed, I think, in throwing a clearer light on the nature of the streamers, and on certain other phenomena which are characteristic of the spark.

scholarly journals On chemical reaction in the electric discharge. I—The chemical effects of impulse discharges

1935 ◽  
Vol 152 (875) ◽  
pp. 158-171 ◽  
Keyword(s):  
Chemical Reaction ◽  
Electric Discharge ◽  
Discharge Tube ◽  
Atomic Hydrogen ◽  
Electric Discharges ◽  
Active Nitrogen ◽  
Atom Concentration ◽  
Chemical Effects ◽  
Spark Gap ◽  
In Series

Although a very large number of studies has been made upon the chemical reactions which can be induced by electric discharges, the effects of controlled condenser sparks appear to have been neglected, with one exception. Wrede has shown that if a large condenser (8 mfd) is charged to a high potential, and then allowed to discharge through a gas at low pressure, a spark gap being inserted in series with the discharge tube proper to increase the breakdown voltage, then hydrogen, oxygen, and nitrogen may be dissociated to the extent of 80, 60, and 40% respectively, the atom concentration being measured upon a most ingenious “diffusion gauge.” The Wrede discharge has been extensively employed by Steiner and his associates in a series of semi-spectroscopic investigations upon active nitrogen and atomic hydrogen, but its use as a means of effecting chemical reaction has not so far received attention.

PROFESSIONAL DEVELOPMENT OF TEACHERS IN HIGHER EDUCATION INSTITUTIONS (BASED ON THE EXPERIENCE OF BORYS GRINCHENKO KYIV UNIVERSITY)

2018 ◽  
Vol 1 ◽  
Author(s):  
Nataliia Vinnikova
Keyword(s):  
Higher Education ◽  
Professional Development ◽  
Higher Education Institutions ◽  
Academic Staff ◽  
Decisive Factor ◽  
School Teachers ◽  
Essential Condition ◽  
Learning And Teaching ◽  
Professional Development Of Teachers ◽  
The Individual

Nowadays, higher education is not only an essential condition for the spiritual and professional development of the individual, but also a decisive factor in socio-economic transformation.Taking into consideration changing nature of learning and teaching at higher education institutions, the need for professional development of teachers is increasing. The main purpose of the thesis is to highlight the problem of professional development of academic staff, its relevance and importance for improving learning and teaching. There will be presented a model of teachers’ skills improvement implemented at Borys Grinchenko Kyiv University (Ukraine), as well as new approaches to the organization of training for higher school teachers that combine different training strategies for their development.

Relacionamentos Virtuais: uma Análise Acerca dos Padrões Comportamentais dos “Catfish”

2018 ◽  
Vol 19 (3) ◽  
pp. 300
Author(s):  
Jefferson Gonçalves Moraes ◽  
Washington Luiz De Oliveira Brandão
Keyword(s):  
Social Support ◽  
Functional Analysis ◽  
Behavior Analysis ◽  
Social Relationships ◽  
Great Influence ◽  
The Internet ◽  
Television Channel ◽  
In Series ◽  
The Individual ◽  
Social Reinforcers

A internet exerce grande influência nas relações sociais, portanto, os relacionamentos afetivos também são modificados, logo, dentre esta categoria surge o relacionamento virtual, possibilitando variadas formas de interação, inclusive a criação de perfis falsos. Para descrever o indivíduo que forja sua identidade ao entrar em um relacionamento, por meio da internet, utiliza-se o termo “catfish”. Com base na Análise do Comportamento se objetivou apresentar uma análise funcional do comportamento do “catfish”, identificar suas características e detectar possíveis funções da classe de respostas, a partir de cinco episódios da série com o mesmo nome. A pesquisa é de caráter bibliográfico e documental, foram utilizados livros, artigos e episódios, disponibilizados pelo canal de televisão a cabo MTV e em sites especializados em séries, para a devida análise. Através da análise funcional foram obtidas informações de antecedentes – respostas – consequências (imediatas e atrasadas), possibilitando a identificação de funções para respostas apresentadas em cada episódio. O resultado da pesquisa aponta que a maioria dos “catfish” apresenta baixo contato com reforçadores sociais (antecedente), o que forneceu uma condição para a criação do perfil falso nas redes sociais (resposta) e obteve como consequência a atenção e suporte social (reforço) indicando, assim, que o comportamento do “catfish” é mantido por reforçamento positivo.Palavras-chaves: Relacionamento Virtual, Catfish, Análise Funcional, Análise do Comportamento.AbstractThe internet exerts a great influence on social relationships, therefore, affective relationships are also modified, thus, within this category emerges the virtual relationship, allowing various forms of interaction, including the creation of fake profiles. To describe the individual who forges their identity when entering into a relationship via the internet, the term “catfish” is used. Based on the Behavior Analysis, it was aimed to present a functional analysis of the “catfish”’s behavior, identify its characteristics and detect possible functions of the class of responses from six episodes of the series with the same name. The research is of bibliographical and documentary character, books, articles and episodes, made available by the cable television channel MTV were used and in sites specialized in series, for the due analysis. Through the functional analysis information about antecedent- responses – consequences were obtained (immediate and delayed), allowing the identification of functions for responses presented in each episode. The result of the research indicates that most catfish have low contact with social reinforcers (antecedent) which provided a condition for creating the false profile in social networks (response) and obtained as a consequence attention and social support (reinforcement), thus indicating that the catfish’s behavior is maintained by positive reinforcement.Keywords: Virtual relationship, Catfish, Functional analysis, Behavior Analysis

scholarly journals The fine-structure of some lines in the visible region of the spectrum of thallium III

1930 ◽  
Vol 129 (809) ◽  
pp. 43-47 ◽  
Keyword(s):  
Fine Structure ◽  
Visible Region ◽  
Nuclear Moment ◽  
Nichrome Wire ◽  
Spark Gap ◽  
High Tension ◽  
In Series ◽  
The One ◽  
Theoretical Results ◽  
Line Classification

From a study of the fine-structure of some lines in the arc spectrum of thallium Schüler and Brück concluded that the nucleus of the thallium atom possessed a moment of momentum given by ½ h /2π and this value was confirmed by work on the first spark spectrum of the element. The value of the nuclear moment being known the structure of the lines in the second spark spectrum could be predicted and the present paper is the account of an investigation of a number of these lines which lie in the visible region, a comparison being drawn between the experimental and the theoretical results. The source of light used was similar to the one employed by McLennan, McLay and Crawford in the excitation of the first and second spark spectra of thallium for the purpose of line classification. It consisted of a quartz tube about 50 cm. long and 1½ cm. in diameter with a plain window in each end and provided with aluminium electrodes sealed into side tubes. The metal whose spectrum was to be studied was scattered along thé bottom of the tube and the tube evacuated. The metal was then vaporised by hear supplied by a coil of nichrome wire wound on the tube. This coil must be wound non-inductively or the desired excitation will not be obtained. The high tension across the terminals was produced by joining them in series with the secondary of a 30,000-volt transformer and a spark gap of about 1 c. m., a condenser being connected in parallel.

scholarly journals The diffraction of cathode rays by thin films of copper, silver and tin

1928 ◽  
Vol 119 (783) ◽  
pp. 668-673 ◽  
Keyword(s):  
Thin Films ◽  
Discharge Tube ◽  
Photographic Plate ◽  
Induction Coil ◽  
Spark Gap ◽  
Diffusion Pump ◽  
Pass Through ◽  
Work Done

The experiments to be described are a continuation of the work done by Prof. G. P. Thomson on the scattering of cathode rays by thin films. The details of the apparatus will be found in his paper. Cathode rays are generated in hydrogen in a discharge tube by an induction coil and pass through a fine tube at the end of which a film is mounted. The rays pass through this film and travel along the camera to the photographic plate which, when an exposure is to be made, is lowered into the path of the rays. The camera is exhausted along with the tube to a low vacuum by a three-stage mercury diffusion pump. The camera and anode are earthed, and the spark gap between two 4 cm. brass balls, which are connected directly across the tube, is read to give the potential through which the electron falls. A mercury break acts as interrupter in the primary and a rectifying valve is used in the secondary.

scholarly journals Bakerian lecture.—On the law of the pressure of gases between 75 and 150 millimetres of mercury

1902 ◽  
Vol 69 (451-458) ◽  
pp. 495-495
Keyword(s):  
Mercury Column ◽  
In Series ◽  
The Law ◽  
Low Pressures

The observations here recorded were intended to bridge over in some degree the gap between the very low pressures (below 1·5 mm.) dealt with in a recent paper and pressures approaching the atmospheric for which the usual mercury column and cathetometer method is adequate. The principal novelty consists in the use of two similar manometric gauges. Pressures in the ratio of 1 : 2 are obtained by the use first of a single gauge and secondly of the two gauges connected in series.

scholarly journals The electric discharge in monatomic gases

1908 ◽  
Vol 80 (536) ◽  
pp. 92-109 ◽  
Keyword(s):  
High Temperature ◽  
Electric Discharge ◽  
Inert Gases ◽  
Inert Gas ◽  
Electric Conduction ◽  
Spark Gap ◽  
Short Summary ◽  
First Results ◽  
Pure Helium ◽  
Metallic Calcium

In a recent paper one of us has described the use of metallic calcium at high temperature for the production of high vacua, and in spectroscopic work as a very perfect chemical absorbent of all except the chemically inert gases. It was shown that helium and argon purified by calcium from traces of common gases or vapours, with which they are in practice invariably contaminated during manipulation, showed a great disinclination to conduct the discharge. In ordinary spectrum-tubes, helium offered a resistance equivalent to an alternative spark-gap of an inch in air, at a pressure of 0·05 mm., and argon at 0·02 mm. of mercury. This behaviour of the monatomic gases, together with the closely-allied phenomenon shown by spectrum-tubes filled with these gases of becoming non-conducting, or “running out,” under the action of the discharge, have now been investigated in detail. A great number of experiments have been performed and a short summary will be given in the present paper. The main object was to settle whether electric conduction in the monatomic gases is essentially different from that in other gases. The first results raised at least a presumption that perfectly pure helium might be unable to conduct the discharge at all, so that the running out of spectrum-tubes might be due to the absorption of the impurities only by the electrodes and not by the absorption of the inert gas itself. This view, however, proved to be untenable.

scholarly journals Evaluation of Filtered Spark Gap on the Lightning Protection of Distribution Transformers: Experimental and Simulation Study

Energies ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3799 ◽  
Author(s):  
Mahdi Pourakbari-Kasmaei ◽  
Farhan Mahmood ◽  
Michal Krbal ◽  
Ludek Pelikan ◽  
Jaroslava Orságová ◽  
...  
Keyword(s):  
Experimental Tests ◽  
Disruptive Effect ◽  
Protection Level ◽  
Spark Gap ◽  
Distribution Transformers ◽  
Double Exponential ◽  
Depth Analysis ◽  
Lightning Impulse ◽  
In Series ◽  
Experimental Laboratory

Protection of transformers, as one of the most expensive equipment in the power system, against lightning overvoltage impulses is a vital task. This paper, for the first time so far, investigates the effects of a filtered spark gap on the protection level of transformers against lightning overvoltage impulses. The filter is an inductor that is placed in series with the transformer and before the spark gap aiming to reduce the voltage at the connection point of the spark gap, and hence, enhancing the protection level of the transformer under lightning overvoltages. The experimental laboratory tests are accomplished on a 400 kVA, 22/0.4 kV, Delta-Star ( Δ − Y ) connection type transformer under 110 kV, and 125 kV overvoltage impulses, whereas the size of the spark gap is set to 80 mm and two inductors of 35 μ H and 119 μ H are considered. In order to perform a more in-depth analysis, a model that works reasonably close to the empirical case is developed in the EMTP-RV software. An optimization algorithm is used to determine the sensitive parameters of the double-exponential function, which is used to reproduce the applied laboratory lightning impulse voltages in the EMTP-RV environment. Moreover, the transformer is modeled according to the Cigre Guidelines (Working Group 02 of Study Committee 33). The behavior of the spark gap is simulated as close as the practical situation using the disruptive effect method. The preciseness of the simulated filtered spark gap model is verified by comparing the results of the simulated model in the EMTP-RV with the results of experimental tests. After verifying the model, different sizes of inductors are studied in the EMTP-RV environment to investigate whether larger or smaller inductors provide better protection for the transformer under lightning conditions. A comparison is performed among the conventional spark gap, surge arrester, and the filtered spark gap to provide a better analysis of the potential of the proposed device. The results indicate that proper sizing of the inductor, within an effective range, slightly enhances the protection level of the transformer.

The starting mechanism of the first stage of the ring discharge

1965 ◽  
Vol 284 (1398) ◽  
pp. 442-454 ◽  
Keyword(s):  
Band Spectrum ◽  
Axial Component ◽  
Uniform Field ◽  
Glass Wall ◽  
Electron Collisions ◽  
Frequency Independent ◽  
Gas Ionization ◽  
Frequency Magnetic Field ◽  
Hydrogen Lines ◽  
Low Pressures

When the high frequency magnetic field of a coil surrounding a cylindrical vessel filled with hydrogen is increased above a critical value, a faint discharge starts which emits the H 2 -band spectrum. If the current in the coil is raised further, an intense ring discharge suddenly develops showing predominantly the atomic hydrogen lines. The first stage is shown to be initiated by the axial component of the electric field of the coil, even when conventional electrostatic screens are used. When the axial component is suppressed, a circumferential component of even twice the axial starting field fails to initiate the discharge. This axial uniform field is calculated for low pressures, at which the mean free electron path exceeds the size of the vessel, by assuming that electrons are multiplied by collisions with the glass wall; it is thus independent of the gas and its density. The dependence of the starting field on length, pressure and frequency is measured using a vessel of variable length and 4 cm radius. Values of 9 and 5V/cm peak at 15 an d 5 Mc/s respectively are found between 10 -4 and 10 -2 mmHg a t 20 cm length, in agreement with theory. For pressures between 0.1 and 1 mmHg the starting field is calculated by balancing the rate of gas ionization by electron collisions and the loss of charge by diffusion to the wall, field-dependent energy losses being allowed for. Its value, now depending on the nature of the gas, rises with increasing pressure and becomes frequency-independent at higher pressures. Again, theory and experiment agree quantitatively.

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