Cold Discharge Research Articles

Transitions between states of high angular momentum in the electronic spectrum of NH2

Electronic spectra of the NH2 radical have been recorded as LIF excitation spectra of the products of photolysis of NH3 in its ÖX bands; as dispersed-emission spectra following laser excitation with this same source; and as emission spectra from a discharge through ammonia recorded with a Fourier-transform spectrometer. All these spectra are dominated by transitions in which the a-axis rotation is excited to high values of the Ka quantum number. By combination of these experimental data with model calculations all the strong features in the spectra have been assigned. The ‘semi-rigid bender’ Renner–Teller hamiltonian gives an adequate representation of these spectra of all Ka provided that v2 is low, but there are strong stretch–bend interactions at higher v2. The excitation mechanism in a cold supersonic discharge source is thought to involve the initial dissociation to NH2+ H of NH3 excited via its à state by electron collision, followed by excitation of the NH2 in a second such collision.

A modified Aarhus negative-ion source

We report intensity, emittance, and brightness measurements both for the Cu − beam as a function of source parameters and for several atomic and molecular negative-ion beams when our modified Aarhus negative-ion source (ANIS) operates on a cold PIG discharge (CPD). A hot PIG discharge (HPD) produces a significantly larger (factor of ∼6) Cu − beam intensity. However, the larger Cu − beam from a HPD also has significantly increased emittance, resulting in only a small improvement (∼40%) in Cu − beam brightness. In the HPD mode the bias of the filaments is important. The relative yields of the atomic negative-ion beams are only in fair agreement with the predictions of the Saha-Langmuir equation. Finally, we compare ANIS with other negative-ion sputter sources.

A Mechanisms and Kinetics Study of Polymeric Thin-Film Deposition in Glow Discharge

Abstract Polymeric thin-film deposition in a capacitively coupled rf glow discharge of styrene has been investigated. A kinetic scheme for the polymerization was proposed in which initiation of monomers by electron impact was followed by propagation and termination as in conventional polymerization, the initiation rate constant being a function of electron temperature alone. Four mechanism models were examined, depending on where each reaction step takes place: in the gas phase or on the substrate. Free-radical polymerization was assumed. Experiments were carried out at pressures ranging from 0.25 to 1.05 Torr and at voltages and currents that yielded cold and stable discharges. Substrate temperature was controlled. Deposition rate was determined by weighing. A regression program was used in addition to experimental tests in which substrate temperature was varied. The best approximation to the plasma polymer deposition process was found to be the following model: monomers are activated in the gas phase by electron bombardment and subsequently diffuse to the substrate where they propagate and terminate, adsorption of monomers on the substrate playing an important role. A rate expression relating polymer film deposition rate to the experimental variables is presented.

FLOW FIELD NEAR AN OCEAN THERMAL ENERGY CONVERSION PLANT

The flow field in the vicinity of an Ocean Thermal Energy Conversion (OTEC) Plant is extremely complex. The plants will normally be located in an area of relatively high surface currents and the location must also be such that a large temperature difference exists between the lower layers and the surface. Locations that demonstrate this characteristic can in many cases be modeled as a two layer fluid as shown in Figure 1. A number of different designs for the OTEC plants are being considered, but they all have one thing in common, a large vertical cold water pipe. This pipe extends from near the surface to some point in the cold water layer (see Figure 1). In some designs this pipe is as large as 40 m in diameter and 460 m in length. Having such a large object penetrating the interface between the two temperature layers in the presence of a shear flow can significantly alter the character of the interface. The highly turbulent wake downstream from the pipe can drastically effect the mixing across this density interface. A conventional heat engine cycle is used in the plant with the high temperature source being the water in the upper layers and the low temperature reservoir being the water from the lower depths. \ Since the temperature difference is small for this type of plant (20° max.), vast quantities of both high and low temperature water must be used. The intake and discharge for the warm water as well as the cold water discharge will be in the upper layer; the intake for the cold water will be in the lower layer at or near the end of the cold water pipe. The flow problem is thus one of a vertical cylinder in a two layer stratified shear flow with sources and sinks located along the cylinder.

Gas-Vapor Separation in a Ranque-Hilsch Vortex Tube

Industrial process air is used as the energy source for Ranque-Hilsch vortex tubes applied to personal protective equipment and in turn supplies breathing air for the individual wearing the protective clothing. The possibility that contaminants in the supply air might be concentrated by gas separation hi the hot or cold air discharges was investigated. Mercury vapor at low concentrations was introduced into the supply air, and the mercury concentrations were monitored at the inlet and at each of the outlets of the vortex tube. A statistical analysis of variance of the data showed that a very small but insignificant (p<0.01) gas separation occurred. The influence of pressure, air volume, and cold air fraction on the mercury concentrations at the outlets was insignificant. This study indicates that the use of industrial process air, meeting accepted air quality standards for breathing purposes, would not increase the hazard to personnel using the vortex tube in conjunction with personal protective equipment.

Synthesis of Biphenyl From Benzene in Microwave Low Pressure Discharge

AbstractIt is attempted to optimize biphenyl yields in 2450 MHz. discharges in pure benzene vapor in the pressure range of 1 to 20 torr. For a benzene throughput of 100 gm/hr. in a ½” tube and for 100 watts dissipated in the discharges the following results were obtained: benzene conversion 10%, biphenyl yield 50%, biphenyl energy yield 45 gm/kWhr. These values are compared with data from other workers and with our investigations in other cold or non-equilibrium discharge plasmas in benzene vapor.

Lake Taneycomo

Significant changes in the fishery of 1,730-acre Lake Taneycomo resulted from the construction of Table Rock Dam immediately upstream on White River because water, released through the dam from a relatively low level, is consequently quite cool. Discharge temperatures range from 40 to 60 F, and the cold water influences a large portion of Lake Taneycomo. Netting indicated an excellent population of warm-water fishes prior to the cold discharge from Table Rock Dam. Since the change to a cold-water environment, only bluegills remain in significant numbers. Growth rates of warm-water species slowed markedly. Fishing pressure on the lower two-thirds of the reservoir was as high as 133 hours per acre annually before the change, with catch rates of over 1.0 fish per hour. White crappies made up half of the catch, by number, with bluegills and largemouth bass next. Low fishing pressure was observed on the upper one-third of the reservoir. About 1,600,000 rainbow trout were stocked to sustain the fishery, following the release of cold water from Table Rock Dam. Fishing pressure on the upper portion of Lake Taneycomo increased to 528 hours per acre with a catch rate of about 0.5 fish per hour. Relative numbers of rainbow trout in the creels increased steadily until they accounted for 99% in 1962 and 1963. Fishing pressure on the lower portion did not increase spectacularly; it was 87 hours per acre in 1963. Catch rate was 0.7 fish per hour, with rainbow trout comprising half the catch. Bluegill, white crappie, and largemouth bass were still taken in limited numbers. Tag returns revealed that the majority of the trout moved upstream, although some were captured as far as 95 miles downstream. Growth of trout tagged, when about 10 inches in length, averaged 0.4 inches per month. Those tagged at 6 inches averaged 0.6 inches per month. Tag returns were 22% of the larger size-group, but only 3% of the smaller size-group.

BASAL BODY TEMPERATURE RECORDINGS IN GYNAECOLOGY AND OBSTETRICS

The experience of 2000 graphs which were recorded by 900 patients over the past 8 years are reviewed in the effort to determine the present place of basal body temperature recordings in gynecology and obstetrics. An important point to make is that in actual practice cooperation was excellent. Only 2% of the patients failed to record these charts satisfactorily. A chart producing a magnification of the small fluctuations in temperature is used. The temperature must be basal and any cold illess discharge bleeding or other symptoms of significance must be noted. An ordinary clinical thermometer is adequate and was used by all the patients. Once the temperature has been up for 48 hours conception is not possible and intercourse can take place for almost 2 weeks of the month with complete confidence that conception will not occur. There is a safe period in most cases before ovulation but this is not at all as certain as in the post-ovulatory phase. The 3 possible sources of error are identified. In addition to being of value as a method of contraception basal body temperatures are helpful in cases of irregular menstruation in the treatment of spasmodic dysmenorrhea and in the diagnosis and treatment of infertility. Certain cases of endometriosis which would otherwise have been overlooked may be detected by this method. These temperature graphs can be useful adjuncts in assessment of certain abnormalities in obstetrics especially bleeding in early pregnancy and postmaturity. The temperature patterns throughout 7 pregnancies are shown and these findings are interpreted.

Basal body temperature recordings in gynaecology and obstetrics.

The experience of 2000 graphs which were recorded by 900 patients over the past 8 years are reviewed in the effort to determine the present place of basal body temperature recordings in gynecology and obstetrics. An important point to make is that in actual practice cooperation was excellent. Only 2% of the patients failed to record these charts satisfactorily. A chart producing a magnification of the small fluctuations in temperature is used. The temperature must be basal and any cold illess discharge bleeding or other symptoms of significance must be noted. An ordinary clinical thermometer is adequate and was used by all the patients. Once the temperature has been up for 48 hours conception is not possible and intercourse can take place for almost 2 weeks of the month with complete confidence that conception will not occur. There is a safe period in most cases before ovulation but this is not at all as certain as in the post-ovulatory phase. The 3 possible sources of error are identified. In addition to being of value as a method of contraception basal body temperatures are helpful in cases of irregular menstruation in the treatment of spasmodic dysmenorrhea and in the diagnosis and treatment of infertility. Certain cases of endometriosis which would otherwise have been overlooked may be detected by this method. These temperature graphs can be useful adjuncts in assessment of certain abnormalities in obstetrics especially bleeding in early pregnancy and postmaturity. The temperature patterns throughout 7 pregnancies are shown and these findings are interpreted.

Abscess of the nasal septum and orbital cellulitis in an infant.

Abscess of the nasal septum is sometimes noted following trauma, infection and other diseases of the nasal structures. Though not common, it is readily recognized and satisfactorily treated when uncomplicated. Before the present era of antibiotics the more serious complications, meningitis and septicemia, sometimes resulted in death. In infants septal abscess is a rare condition, whether it occurs with or without complications. REPORT OF A CASE G. L., a Negro male infant 25 days of age, was admitted to Dooley Hospital of the Medical College of Virginia on Aug. 25, 1949. The following history was elicited. At birth, a midwife had assisted, and his condition was considered normal by her. When the patient was 17 days old the family physician was called for him and nose drops were prescribed for a head cold and nasal discharge. Two days later swelling of the left eye was noted. Six daily injections (dosage

Contact Phenomena in Telephone Switching Circuits

The phenomena occurring at the closing and opening of contacts carrying weak currents have been investigated by means which include a study of the high-frequency transient voltages and currents. These influence the erosion in a complex manner which varies with contact materials, surface conditions, and surrounding atmosphere. Three principal classes of effect have been distinguished. These are: (1) Disruptive spark-overs initiating a series of metallic arcs lasting less than a microsecond each. (2) A nitrogen-gas glow discharge at about 300 volts, preceded by a brief group of disruptive spark-overs. (3) High field breakdowns due to cold point discharges which cause transient metallic closures of approaching contacts and similar transient reclosures of separating contacts.

Contact phenomena in telephone switching circuits

The phenomena occurring at the closing and opening of contacts carrying weak currents have been investigated by means which include a study of the high-frequency transient voltages and currents. These influence the erosion in a complex manner which varies with contact materials, surface conditions, and surrounding atmosphere. Three principal classes of effect have been distinguished. These are: (1) Disruptive spark-overs initiating a series of metallic arcs lasting less than a microsecond each. (2) A nitrogen-gas glow discharge at about 300 volts, preceded by a brief group of disruptive spark-overs. (3) High field breakdowns due to cold point discharges which cause transient metallic closures of approaching contacts and similar transient reclosures of separating contacts.

Contact Phenomena in Telephone Switching Circuits*

The phenomena occurring at the closing and opening of contacts carrying weak currents have been investigated by means which include a study of the high-frequency transient voltages and currents. These influence the erosion in a complex manner which varies with contact materials, surface conditions and surrounding atmosphere. Three principal classes of effect have been distinguished. These are: (1) Disruptive sparkovers initiating a series of metallic arcs lasting less than a microsecond each; (2) A nitrogen gas glow discharge at about 300 volts, preceded by a brief group of disruptive sparkovers; (3) High field breakdowns due to cold point discharges which cause transient metallic closures of approaching contacts and similar transient reclosures of separating contacts.

An Electron Diffraction Camera

MESSRS. W. EDWARDS AND Co., Allendale Works, Vaughan Road, London, S.E.5, have recently published details of their Finch electron diffraction camera intended for industrial research. This camera is of the type developed by Prof. G. Ingle Finch, who has done so much to improve the technique of electron diffraction. The camera uses a cold cathod discharge tube as a source of electrons. The fine beam, which is necessary for a sharp diffraction pattern, is obtained by using a series of diaphragms and by focusing the beam upon the screen with a magnetic coil. A useful feature is that both the diaphragm and specimen holders are standardized so that they will fit any of the six ports in the instrument. Moreover, all the necessary adjustments of the diaphragm and specimen can be made in vacua from the outside. The joints are ground and polished flats held in contact by the atmospheric pressure, a point of importance in routine work where quickness in changing specimens is essential. In this instrument the specimen can be exchanged and the system evacuated in a matter of minutes. Only one criticism—a minor one—can be made. The shape and size of the window are such that the eyes must be held quite close if the whole pattern is to be seen, and the screen is then rather near for comfortable vision. Suitable pumps are supplied, a variety of systems being available to suit individual needs, or a standard unit is made up ready for use. This instrument is noteworthy as it marks the entry of the diffraction camera into the industrial research laboratory, where it should yield valuable information upon metallic surface structure, to mention only one of the many possible industrial fields of investigation.

The Present Theory of Electric Conduction

The present theory of electric conduction in solid conductors and semiconductors is reviewed here by a recognized authority who interprets some of the results of modern physical research in the light of their bearing upon the theory of electric conductivity. First the author gives a short review of the present theory, then discusses the breakdown of ionic crystals, the quantum theory, and cold discharge phenomena.

The present theory of electric conduction

The present theory of electric conduction in solid conductors and semiconductors is reviewed here by a recognized authority who interprets some of the results of modern physical research in the light of their bearing upon the theory of electric conductivity. First the author gives a short review of the present theory, then discusses the breakdown of ionic crystals, the quantum theory, and cold discharge phenomena.

CII.Luminous carborundum detector and detection effect and oscillations with crystals

Abstract In this paper are described further observations on the phenomenon on the luminescence produced at the contact of a carborundum detector in connexion with a view on luminescence as a consequence of the process in the contact which is very similar to cold electronic discharge.

On the extraction of electrons from cold conductors in intense electric fields

The discovery of this phenomenon seems to have evolved gradually from Earhart's* experiments on very short sparks in 1901. Since 1913 I have been familiar with the fact that in strong fields cold discharges could be made to pass in highly exhausted tubes under conditions which seemed to preclude the co-operation of gas as a factor. The phenomena appeared erratic and difficult to interpret. Recently, rapid progress has been made in the investigation of this effect especially owing to the researches of Gossling and of Millikan and Eyring, which have put it on a firm basis. Both Gossling and Millikan and Eyring have found, among other interesting facts, that with field strengths of the order of one million volts per cm. electrons can be drawn out of tungsten without the co-operation of gas, that the currents vary very rapidly with the applied voltage, and under proper conditions the current is reproducible and a continuous function of the applied voltage over a wide range, and that the currents at a given voltage are independent of the temperature provided the temperature is not so high as to approach the temperatures at which thermionic emission becomes appreciable.