Pub Date : 1967-12-01DOI: 10.1088/0508-3443/18/12/310
D. Griffin
Frequency-dependent expressions are obtained for the major types of bimodal cavity unbalancing that can arise from imperfections. These expressions are used to devise a procedure for achieving balance over a wide band of frequencies. Details of the systematic adjustment of an array of balancing probes are given and typical results for an X-band square-section cavity are presented.
{"title":"Wide-band balancing of bimodal cavities used for microwave measurements on gyrotropic media","authors":"D. Griffin","doi":"10.1088/0508-3443/18/12/310","DOIUrl":"https://doi.org/10.1088/0508-3443/18/12/310","url":null,"abstract":"Frequency-dependent expressions are obtained for the major types of bimodal cavity unbalancing that can arise from imperfections. These expressions are used to devise a procedure for achieving balance over a wide band of frequencies. Details of the systematic adjustment of an array of balancing probes are given and typical results for an X-band square-section cavity are presented.","PeriodicalId":9350,"journal":{"name":"British Journal of Applied Physics","volume":"61 1","pages":"1743-1751"},"PeriodicalIF":0.0,"publicationDate":"1967-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73796949","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 : 1967-12-01DOI: 10.1088/0508-3443/18/12/306
C. A. Calow, P. Bayer, G. P. McCarthy
This paper describes procedures for (i) the sizing and orientation determination of `whiskers' using an interference microscope and (ii) the evaluation of the mechanical properties of whiskers using a Techne micro-tensile tester. The Young's modulus of α-Al2O3 whiskers can be markedly affected by both small tapers in the whisker shape and extraneous extensions occurring in the grip adhesive. Taper error can apparently increase the modulus by more than 100%, while extraneous grip-adhesive extensions decrease the modulus proportionally with decreasing gauge length. It is concluded that the Young's modulus of α-Al2O3 whiskers matches that for bulk single crystals of α-Al2O3 and that this value differs only slightly for various growth directions.
{"title":"The sizing and mechanical testing of whiskers of α-Al2O3","authors":"C. A. Calow, P. Bayer, G. P. McCarthy","doi":"10.1088/0508-3443/18/12/306","DOIUrl":"https://doi.org/10.1088/0508-3443/18/12/306","url":null,"abstract":"This paper describes procedures for (i) the sizing and orientation determination of `whiskers' using an interference microscope and (ii) the evaluation of the mechanical properties of whiskers using a Techne micro-tensile tester. The Young's modulus of α-Al2O3 whiskers can be markedly affected by both small tapers in the whisker shape and extraneous extensions occurring in the grip adhesive. Taper error can apparently increase the modulus by more than 100%, while extraneous grip-adhesive extensions decrease the modulus proportionally with decreasing gauge length. It is concluded that the Young's modulus of α-Al2O3 whiskers matches that for bulk single crystals of α-Al2O3 and that this value differs only slightly for various growth directions.","PeriodicalId":9350,"journal":{"name":"British Journal of Applied Physics","volume":"8 1","pages":"1715-1836"},"PeriodicalIF":0.0,"publicationDate":"1967-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85649180","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 : 1967-11-01DOI: 10.1088/0508-3443/18/11/306
C. Burdett, R. B. Layng
The variation of internal friction with strain amplitude at temperatures of 115, 168, 215, 245 and 298°K has been measured using a torsional pendulum at a frequency of 1 c/s. The damping with a magnetic origin has been separated from the total damping by a method due to Granato and Lucke, and the results have been explained in terms of the irreversible movement of 90° domain boundaries. A simple analysis using domain theory predicts a relation between the stress at peak damping and the magnetic field at maximum susceptibility. For gadolinium this field is 006 Oe at 245°K. A simple treatment of the variation of peak damping with temperature shows qualitative agreement with the results.
{"title":"Magnetic damping in gadolinium","authors":"C. Burdett, R. B. Layng","doi":"10.1088/0508-3443/18/11/306","DOIUrl":"https://doi.org/10.1088/0508-3443/18/11/306","url":null,"abstract":"The variation of internal friction with strain amplitude at temperatures of 115, 168, 215, 245 and 298°K has been measured using a torsional pendulum at a frequency of 1 c/s. The damping with a magnetic origin has been separated from the total damping by a method due to Granato and Lucke, and the results have been explained in terms of the irreversible movement of 90° domain boundaries. A simple analysis using domain theory predicts a relation between the stress at peak damping and the magnetic field at maximum susceptibility. For gadolinium this field is 006 Oe at 245°K. A simple treatment of the variation of peak damping with temperature shows qualitative agreement with the results.","PeriodicalId":9350,"journal":{"name":"British Journal of Applied Physics","volume":"78 1","pages":"1551-1557"},"PeriodicalIF":0.0,"publicationDate":"1967-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90845795","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 : 1967-11-01DOI: 10.1088/0508-3443/18/11/312
W. J. Takei, M. Francombe
An x-ray topographic technique has been used for the study of the spatial distribution of polytypes in silicon carbide crystals. The results for a typical mixed crystal indicate that analyses based upon the more conventional optical and x-ray Laue studies may be subject to misinterpretation. The topographic method clarifies the significance of the boundaries which are observed optically.
{"title":"X-ray topographic observation of polytype distributions in silicon carbide","authors":"W. J. Takei, M. Francombe","doi":"10.1088/0508-3443/18/11/312","DOIUrl":"https://doi.org/10.1088/0508-3443/18/11/312","url":null,"abstract":"An x-ray topographic technique has been used for the study of the spatial distribution of polytypes in silicon carbide crystals. The results for a typical mixed crystal indicate that analyses based upon the more conventional optical and x-ray Laue studies may be subject to misinterpretation. The topographic method clarifies the significance of the boundaries which are observed optically.","PeriodicalId":9350,"journal":{"name":"British Journal of Applied Physics","volume":"53 58 1","pages":"1589"},"PeriodicalIF":0.0,"publicationDate":"1967-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89261008","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 : 1967-11-01DOI: 10.1088/0508-3443/18/11/303
M. Brown, P. Porteous
Processes are described for producing InAs diode lasers by liquid phase epitaxy. Measurements have been made on these lasers of wavelength of emission, power output, internal and external quantum efficiency, near- and far-field patterns and delay between current pulse and radiation output. We conclude that the efficiency of the lasers is low due partly to `spotty' emission and partly to a low non-radiative lifetime.
{"title":"The technology and properties of epitaxial indium arsenide lasers","authors":"M. Brown, P. Porteous","doi":"10.1088/0508-3443/18/11/303","DOIUrl":"https://doi.org/10.1088/0508-3443/18/11/303","url":null,"abstract":"Processes are described for producing InAs diode lasers by liquid phase epitaxy. Measurements have been made on these lasers of wavelength of emission, power output, internal and external quantum efficiency, near- and far-field patterns and delay between current pulse and radiation output. We conclude that the efficiency of the lasers is low due partly to `spotty' emission and partly to a low non-radiative lifetime.","PeriodicalId":9350,"journal":{"name":"British Journal of Applied Physics","volume":"16 1","pages":"1527-1535"},"PeriodicalIF":0.0,"publicationDate":"1967-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82523685","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 : 1967-11-01DOI: 10.1088/0508-3443/18/11/125
P. Stewart, R. Wilson
A relationship has been observed between the density of triangular etch pits on (1010) faces of some single-crystal samples of CdS and the relative difficulty encountered in making indium-diffused ohmic contacts to these specimens. Various workers have observed a relationship between etch-pit and dislocation densities in CdS. The results suggest that the important diffusion mechanism in making contacts is by diffusion into dislocations.
{"title":"Formation of ohmic contacts to cadmium sulphide","authors":"P. Stewart, R. Wilson","doi":"10.1088/0508-3443/18/11/125","DOIUrl":"https://doi.org/10.1088/0508-3443/18/11/125","url":null,"abstract":"A relationship has been observed between the density of triangular etch pits on (1010) faces of some single-crystal samples of CdS and the relative difficulty encountered in making indium-diffused ohmic contacts to these specimens. Various workers have observed a relationship between etch-pit and dislocation densities in CdS. The results suggest that the important diffusion mechanism in making contacts is by diffusion into dislocations.","PeriodicalId":9350,"journal":{"name":"British Journal of Applied Physics","volume":"47 1","pages":"1657-1658"},"PeriodicalIF":0.0,"publicationDate":"1967-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87981601","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 : 1967-11-01DOI: 10.1088/0508-3443/18/11/420
B. J. Bailey, K. Kellner
The thermal conductivity of argon has been determined in the critical region using a concentric-cylinder type of cell. It was observed that the conductivity isobars exhibited maxima which became more pronounced as the critical point was approached. The locus of the maxima was found to coincide with the critical isochore.
{"title":"The thermal conductivity of argon near the critical point","authors":"B. J. Bailey, K. Kellner","doi":"10.1088/0508-3443/18/11/420","DOIUrl":"https://doi.org/10.1088/0508-3443/18/11/420","url":null,"abstract":"The thermal conductivity of argon has been determined in the critical region using a concentric-cylinder type of cell. It was observed that the conductivity isobars exhibited maxima which became more pronounced as the critical point was approached. The locus of the maxima was found to coincide with the critical isochore.","PeriodicalId":9350,"journal":{"name":"British Journal of Applied Physics","volume":"29 1","pages":"1645-1647"},"PeriodicalIF":0.0,"publicationDate":"1967-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90436533","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 : 1967-11-01DOI: 10.1088/0508-3443/18/11/317
L. Ward, A. Nag
The sensitivity studies for methods of measuring n, k and d/λ of a thin film by optical methods have been extended to cases of non-normal incidence. The results for each pair of parameters are exhibited in the form of sensitivity diagrams. The diagrams for (Tp, Ts) and (Rp, Rs) at θ = 45°, 60° and 75° show overall high sensitivity over the region 0 3, k > 3.
{"title":"Theoretical studies of the sensitivities of non-normal incidence methods for measuring the optical constants of thin films","authors":"L. Ward, A. Nag","doi":"10.1088/0508-3443/18/11/317","DOIUrl":"https://doi.org/10.1088/0508-3443/18/11/317","url":null,"abstract":"The sensitivity studies for methods of measuring n, k and d/λ of a thin film by optical methods have been extended to cases of non-normal incidence. The results for each pair of parameters are exhibited in the form of sensitivity diagrams. The diagrams for (Tp, Ts) and (Rp, Rs) at θ = 45°, 60° and 75° show overall high sensitivity over the region 0 3, k > 3.","PeriodicalId":9350,"journal":{"name":"British Journal of Applied Physics","volume":"60 1","pages":"1629-1636"},"PeriodicalIF":0.0,"publicationDate":"1967-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89562399","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 : 1967-11-01DOI: 10.1088/0508-3443/18/11/309
W. H. Andersen
The crossed homogeneous electrostatic and magnetic deflection fields of an analyser (Wien filter) have been formed by two condenser plates and two pairs of coils. The optimum operating conditions are shown to require unit magnification, contrary to the view of other authors. By varying the current ratio in the coils, a desired inhomogeneity can be introduced in the magnetic field and with this the second-order angular aberration can be corrected. The possibility of a double-focusing Wien filter is discussed.
{"title":"Optimum adjustment and correction of the Wien filter","authors":"W. H. Andersen","doi":"10.1088/0508-3443/18/11/309","DOIUrl":"https://doi.org/10.1088/0508-3443/18/11/309","url":null,"abstract":"The crossed homogeneous electrostatic and magnetic deflection fields of an analyser (Wien filter) have been formed by two condenser plates and two pairs of coils. The optimum operating conditions are shown to require unit magnification, contrary to the view of other authors. By varying the current ratio in the coils, a desired inhomogeneity can be introduced in the magnetic field and with this the second-order angular aberration can be corrected. The possibility of a double-focusing Wien filter is discussed.","PeriodicalId":9350,"journal":{"name":"British Journal of Applied Physics","volume":"55 1","pages":"1573-1579"},"PeriodicalIF":0.0,"publicationDate":"1967-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73100619","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 : 1967-11-01DOI: 10.1088/0508-3443/18/11/313
K. Close, J. Yarwood
Experimental results, including those of the authors, for the variation with energy below 1 kev of the trapping efficiency S0 for noble gas ions incident upon atomically clean polycrystalline tungsten are discussed and compared. A suggestion by Kornelsen, that the threshold energy (at S0 = 10-5) is determined by the interaction energy between the neutral gas atom and a surface tungsten atom, has been extended and a theory developed enabling a value of S0 to be calculated using the repulsive interaction potentials calculated by Abrahamson. The curves derived from this theory show good agreement with the experimental curves for the four gas-metal combinations He-W, Ne-W, Ar-W and Kr-W. For low energies and low total ion flux, these calculations also indicate the variation of trapping efficiency with the target crystal face presented to the incident ion.
{"title":"The trapping of low-energy noble gas ions at a tungsten surface","authors":"K. Close, J. Yarwood","doi":"10.1088/0508-3443/18/11/313","DOIUrl":"https://doi.org/10.1088/0508-3443/18/11/313","url":null,"abstract":"Experimental results, including those of the authors, for the variation with energy below 1 kev of the trapping efficiency S0 for noble gas ions incident upon atomically clean polycrystalline tungsten are discussed and compared. A suggestion by Kornelsen, that the threshold energy (at S0 = 10-5) is determined by the interaction energy between the neutral gas atom and a surface tungsten atom, has been extended and a theory developed enabling a value of S0 to be calculated using the repulsive interaction potentials calculated by Abrahamson. The curves derived from this theory show good agreement with the experimental curves for the four gas-metal combinations He-W, Ne-W, Ar-W and Kr-W. For low energies and low total ion flux, these calculations also indicate the variation of trapping efficiency with the target crystal face presented to the incident ion.","PeriodicalId":9350,"journal":{"name":"British Journal of Applied Physics","volume":"81 1","pages":"1593-1598"},"PeriodicalIF":0.0,"publicationDate":"1967-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90579964","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}
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