Pub Date : 1967-08-01DOI: 10.1088/0508-3443/18/8/301
C. Andersen
The quality of a microanalysis by means of X-rays may be defined in terms of the degree of spatial resolution attained, the sensitivity of detection, the precision of the measurement and the accuracy of the measurement. These parameters are discussed in relation to the ultra-soft X-ray region. The ability to perform a quantitative analysis receives special attention, and is found to be greatly affected by the nature of the chemical bonding of the specimen, the correction theory used, and the availability of accurate mass-absorption coefficient data.
{"title":"The quality of x-ray microanalysis in the ultra-soft x-ray region","authors":"C. Andersen","doi":"10.1088/0508-3443/18/8/301","DOIUrl":"https://doi.org/10.1088/0508-3443/18/8/301","url":null,"abstract":"The quality of a microanalysis by means of X-rays may be defined in terms of the degree of spatial resolution attained, the sensitivity of detection, the precision of the measurement and the accuracy of the measurement. These parameters are discussed in relation to the ultra-soft X-ray region. The ability to perform a quantitative analysis receives special attention, and is found to be greatly affected by the nature of the chemical bonding of the specimen, the correction theory used, and the availability of accurate mass-absorption coefficient data.","PeriodicalId":9350,"journal":{"name":"British Journal of Applied Physics","volume":"22 1","pages":"1033-1043"},"PeriodicalIF":0.0,"publicationDate":"1967-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77203041","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1967-08-01DOI: 10.1088/0508-3443/18/8/307
R. Jansson, L. A. Middleton
The degree of dissociation of molecular nitrogen in 2450 MHz discharges in dry N2 and N2-He mixtures at pressures between 09 and 60 torr have been measured by titration with nitric oxide. Using an X-band resonant-cavity technique, electron (ion) densities in the discharges have also been measured. It is concluded that atoms originate chiefly from thermal dissociation at a quasi-equilibrium gas temperature in the range 3000-3700°K, the neutral gas having been heated by random collisions with electrons at much higher temperatures. Between 05 and 2% of the power coupled to the discharge is used in heating the gas.
{"title":"Dissociation of N 2 in 2450 MHz discharges","authors":"R. Jansson, L. A. Middleton","doi":"10.1088/0508-3443/18/8/307","DOIUrl":"https://doi.org/10.1088/0508-3443/18/8/307","url":null,"abstract":"The degree of dissociation of molecular nitrogen in 2450 MHz discharges in dry N2 and N2-He mixtures at pressures between 09 and 60 torr have been measured by titration with nitric oxide. Using an X-band resonant-cavity technique, electron (ion) densities in the discharges have also been measured. It is concluded that atoms originate chiefly from thermal dissociation at a quasi-equilibrium gas temperature in the range 3000-3700°K, the neutral gas having been heated by random collisions with electrons at much higher temperatures. Between 05 and 2% of the power coupled to the discharge is used in heating the gas.","PeriodicalId":9350,"journal":{"name":"British Journal of Applied Physics","volume":"407 1","pages":"1079-1083"},"PeriodicalIF":0.0,"publicationDate":"1967-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78076521","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1967-08-01DOI: 10.1088/0508-3443/18/8/304
W. Gibbs
Measurements of the variation of formation time of a Q-switched ruby laser as a function of loop gain are presented. The loop gains were calculated from integrated pump intensities and the measured resonator loss at threshold. The relationship between formation time and loop gain predicted by fast Q-switching theory was confirmed. Although large optical distortions are to be expected in rubies pumped to Q-switching levels, no indication of increasing resonator loss was found under these conditions.
{"title":"Formation time and resonator loss in a Q-switched ruby laser","authors":"W. Gibbs","doi":"10.1088/0508-3443/18/8/304","DOIUrl":"https://doi.org/10.1088/0508-3443/18/8/304","url":null,"abstract":"Measurements of the variation of formation time of a Q-switched ruby laser as a function of loop gain are presented. The loop gains were calculated from integrated pump intensities and the measured resonator loss at threshold. The relationship between formation time and loop gain predicted by fast Q-switching theory was confirmed. Although large optical distortions are to be expected in rubies pumped to Q-switching levels, no indication of increasing resonator loss was found under these conditions.","PeriodicalId":9350,"journal":{"name":"British Journal of Applied Physics","volume":"14 1","pages":"1061-1063"},"PeriodicalIF":0.0,"publicationDate":"1967-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74279073","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1967-08-01DOI: 10.1088/0508-3443/18/8/315
G. Vinogradov, Y. Yanovsky, E. Frenkin
This paper describes a study of the temperature dependence of the dynamic characteristic and friction in the melting and crystallization region of linear polyethylene, isotactic polypropylene and their 9: 1, 5: 5 and 1: 9 mixtures. The measurements were made on a Ferry-Fitzgerald type transducer and on a tribometer. The temperature-dependence curves of shear storage and loss moduli, the loss tangent, the friction and the slider-to-polymer contact area of the above materials were plotted. It is suggested that correlation of the dynamic and tribometric characteristics of polymers may be expected when the nominal contact area of the friction body approximates its actual value. Comparison of these characteristics for linear polyethylene in its pre-melting range reveal only a qualitative similarity between the temperature dependence of its shear storage and loss moduli on the one hand, and the ratio of the loads and friction to the slider-to-polymer contact area on the other. Investigation of mixtures of crystalline polymers has made it possible to determine the sequence of melting of the components in the mixture or the formation of a single-phase system at a definite component concentration. After crystallization of both components, two-phase binary systems containing crystallizing polymers have the structure of two interlaced frameworks formed by the polymer crystallites.
{"title":"Friction and dynamic mechanical characteristics of crystalline polymers during melting","authors":"G. Vinogradov, Y. Yanovsky, E. Frenkin","doi":"10.1088/0508-3443/18/8/315","DOIUrl":"https://doi.org/10.1088/0508-3443/18/8/315","url":null,"abstract":"This paper describes a study of the temperature dependence of the dynamic characteristic and friction in the melting and crystallization region of linear polyethylene, isotactic polypropylene and their 9: 1, 5: 5 and 1: 9 mixtures. The measurements were made on a Ferry-Fitzgerald type transducer and on a tribometer. The temperature-dependence curves of shear storage and loss moduli, the loss tangent, the friction and the slider-to-polymer contact area of the above materials were plotted. It is suggested that correlation of the dynamic and tribometric characteristics of polymers may be expected when the nominal contact area of the friction body approximates its actual value. Comparison of these characteristics for linear polyethylene in its pre-melting range reveal only a qualitative similarity between the temperature dependence of its shear storage and loss moduli on the one hand, and the ratio of the loads and friction to the slider-to-polymer contact area on the other. Investigation of mixtures of crystalline polymers has made it possible to determine the sequence of melting of the components in the mixture or the formation of a single-phase system at a definite component concentration. After crystallization of both components, two-phase binary systems containing crystallizing polymers have the structure of two interlaced frameworks formed by the polymer crystallites.","PeriodicalId":9350,"journal":{"name":"British Journal of Applied Physics","volume":"128 1","pages":"1141-1150"},"PeriodicalIF":0.0,"publicationDate":"1967-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88716395","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1967-08-01DOI: 10.1088/0508-3443/18/8/302
T. Cowell, J. Woods
A method of evaluating experimentally determined thermally stimulated current curves by a process of successive approximation is described. The method is essentially one of curve fitting and an excellent fit is eventually obtained between the theoretical and experimental curves. The process of curve fitting serves to determine the electron-trapping parameters. The technique can be used for the two extreme cases of trap emptying: emptying with no retrapping and emptying with fast retrapping. The technique is illustrated by its application to some experimental results obtained from CdS crystals.
{"title":"The evaluation of thermally stimulated current curves","authors":"T. Cowell, J. Woods","doi":"10.1088/0508-3443/18/8/302","DOIUrl":"https://doi.org/10.1088/0508-3443/18/8/302","url":null,"abstract":"A method of evaluating experimentally determined thermally stimulated current curves by a process of successive approximation is described. The method is essentially one of curve fitting and an excellent fit is eventually obtained between the theoretical and experimental curves. The process of curve fitting serves to determine the electron-trapping parameters. The technique can be used for the two extreme cases of trap emptying: emptying with no retrapping and emptying with fast retrapping. The technique is illustrated by its application to some experimental results obtained from CdS crystals.","PeriodicalId":9350,"journal":{"name":"British Journal of Applied Physics","volume":"27 1","pages":"1045-1051"},"PeriodicalIF":0.0,"publicationDate":"1967-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88212053","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1967-08-01DOI: 10.1088/0508-3443/18/8/318
H. Pyne, R. Wilson, B. Soole
It is shown that droplets may be removed from an air stream by impaction on a number of filaments mounted radially on a central disk which is rotated in a plane at right angles to the direction of flow. Published theoretical and experimental results indicate that particles will be impacted on the filaments when the rate of rotation of the disk is sufficient for the Stokes number of the smallest particle which is to be removed to be equal to at least 12. Experiments are described with a filter composed of 390 filaments, 10 cm long and 460 μm thick, mounted on a disk 56 cm in diameter. When the disk was rotated at 1900 rev min-1, just sufficient to ensure that the Stokes number for 4 μm particles of unit-density material was 12 and that the air flow of 2500 ft3 min-1 was fully swept, the measured filtration efficiency was equivalent to 90 ± 5% for 4 μm droplets of unit-density material and progressively more for the larger sizes. Filtration efficiencies were determined by the use of sodium-24 as a radioactive tracer in conjunction with cascade impactors. Filtration devices of the type described have the advantages that they are compact, self-cleaning and offer little resistance to large rates of air flow.
{"title":"Air filtration by moving filaments","authors":"H. Pyne, R. Wilson, B. Soole","doi":"10.1088/0508-3443/18/8/318","DOIUrl":"https://doi.org/10.1088/0508-3443/18/8/318","url":null,"abstract":"It is shown that droplets may be removed from an air stream by impaction on a number of filaments mounted radially on a central disk which is rotated in a plane at right angles to the direction of flow. Published theoretical and experimental results indicate that particles will be impacted on the filaments when the rate of rotation of the disk is sufficient for the Stokes number of the smallest particle which is to be removed to be equal to at least 12. Experiments are described with a filter composed of 390 filaments, 10 cm long and 460 μm thick, mounted on a disk 56 cm in diameter. When the disk was rotated at 1900 rev min-1, just sufficient to ensure that the Stokes number for 4 μm particles of unit-density material was 12 and that the air flow of 2500 ft3 min-1 was fully swept, the measured filtration efficiency was equivalent to 90 ± 5% for 4 μm droplets of unit-density material and progressively more for the larger sizes. Filtration efficiencies were determined by the use of sodium-24 as a radioactive tracer in conjunction with cascade impactors. Filtration devices of the type described have the advantages that they are compact, self-cleaning and offer little resistance to large rates of air flow.","PeriodicalId":9350,"journal":{"name":"British Journal of Applied Physics","volume":"44 1","pages":"1177-1191"},"PeriodicalIF":0.0,"publicationDate":"1967-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82109200","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1967-08-01DOI: 10.1088/0508-3443/18/8/310
T. Quinn
A new calculation has been made of the emissivities of cylinders closed at one end and having in the other end an opening of radius either equal to or smaller than the radius of the cylinder. The results are presented for cylinders having diffusely reflecting walls with dimensions such that the emissivity is very close to unity. The method of calculation is that devised by de Vos, but fewer approximations are made, and significantly higher values of emissivity obtained. Comparison with the results of other calculations leads to the conclusion that those of both Buckley and Gouffe are seriously in error for this type of cavity while those of Sparrow et al. are in very close agreement with the present results though obtained by quite different methods. Estimates are made of the effects on the emissivity of internal baffles and grooved surfaces.
{"title":"The calculation of the emissivity of cylindrical cavities giving near black-body radiation","authors":"T. Quinn","doi":"10.1088/0508-3443/18/8/310","DOIUrl":"https://doi.org/10.1088/0508-3443/18/8/310","url":null,"abstract":"A new calculation has been made of the emissivities of cylinders closed at one end and having in the other end an opening of radius either equal to or smaller than the radius of the cylinder. The results are presented for cylinders having diffusely reflecting walls with dimensions such that the emissivity is very close to unity. The method of calculation is that devised by de Vos, but fewer approximations are made, and significantly higher values of emissivity obtained. Comparison with the results of other calculations leads to the conclusion that those of both Buckley and Gouffe are seriously in error for this type of cavity while those of Sparrow et al. are in very close agreement with the present results though obtained by quite different methods. Estimates are made of the effects on the emissivity of internal baffles and grooved surfaces.","PeriodicalId":9350,"journal":{"name":"British Journal of Applied Physics","volume":"89 3 1","pages":"1105-1113"},"PeriodicalIF":0.0,"publicationDate":"1967-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87713887","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1967-08-01DOI: 10.1088/0508-3443/18/8/423
J. A. Fraunhofer
The linear expansion of the iron cubic lattice by aluminium additions has been determined by x-ray diffraction and the results compared with earlier work.
通过x射线衍射确定了铝的加入使铁立方晶格线性膨胀，并将结果与早期的工作进行了比较。
{"title":"Lattice parameters of iron-aluminium alloys","authors":"J. A. Fraunhofer","doi":"10.1088/0508-3443/18/8/423","DOIUrl":"https://doi.org/10.1088/0508-3443/18/8/423","url":null,"abstract":"The linear expansion of the iron cubic lattice by aluminium additions has been determined by x-ray diffraction and the results compared with earlier work.","PeriodicalId":9350,"journal":{"name":"British Journal of Applied Physics","volume":"28 1","pages":"1212-1212"},"PeriodicalIF":0.0,"publicationDate":"1967-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78338227","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1967-08-01DOI: 10.1088/0508-3443/18/8/317
I. Ward
Expressions have been derived for the optical birefringence and elastic constants of an initially isotropic polymer or fibre subjected to a two-stage stretching process. The first stage is carried out at high temperatures, with the polymer or fibre in its rubbery state, and the second stage is cold drawing. The predicted birefringences and extensional moduli show good agreement with experimental data for polyethylene terephthalate.
{"title":"The influence of pre-orientation on the optical and mechanical anisotropy of drawn polymers","authors":"I. Ward","doi":"10.1088/0508-3443/18/8/317","DOIUrl":"https://doi.org/10.1088/0508-3443/18/8/317","url":null,"abstract":"Expressions have been derived for the optical birefringence and elastic constants of an initially isotropic polymer or fibre subjected to a two-stage stretching process. The first stage is carried out at high temperatures, with the polymer or fibre in its rubbery state, and the second stage is cold drawing. The predicted birefringences and extensional moduli show good agreement with experimental data for polyethylene terephthalate.","PeriodicalId":9350,"journal":{"name":"British Journal of Applied Physics","volume":"4 10","pages":"1165-1175"},"PeriodicalIF":0.0,"publicationDate":"1967-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91425099","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1967-08-01DOI: 10.1088/0508-3443/18/8/320
C. Dodson
A new descriptive formalism is introduced to represent the state of a bonded random network of fibres, such as paper, when subjected to mechanical deformation. Energy is considered to be distributed among the lengths of free fibre between inter-fibre bonds and a criterion for the fracture of these bonds is postulated. The theory is used in the present paper to derive the cumulative fracture of bonds as a function of time in a network which suffers a uniform rate of elongation. Good agreement was obtained with experimental recordings of the failure of bonds in a thin sheet of paper. No systematic influence of the rate of straining on the mode of bond failure was detected.
{"title":"A new approach to the fracture of bonds in a random fibrous network such as paper","authors":"C. Dodson","doi":"10.1088/0508-3443/18/8/320","DOIUrl":"https://doi.org/10.1088/0508-3443/18/8/320","url":null,"abstract":"A new descriptive formalism is introduced to represent the state of a bonded random network of fibres, such as paper, when subjected to mechanical deformation. Energy is considered to be distributed among the lengths of free fibre between inter-fibre bonds and a criterion for the fracture of these bonds is postulated. The theory is used in the present paper to derive the cumulative fracture of bonds as a function of time in a network which suffers a uniform rate of elongation. Good agreement was obtained with experimental recordings of the failure of bonds in a thin sheet of paper. No systematic influence of the rate of straining on the mode of bond failure was detected.","PeriodicalId":9350,"journal":{"name":"British Journal of Applied Physics","volume":"33 1","pages":"1199-1204"},"PeriodicalIF":0.0,"publicationDate":"1967-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90830515","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：