Pub Date : 1989-12-01DOI: 10.1088/0022-3735/22/12/016
N. C. Kerr, S. Clark, D. C. Emmony
The construction and performance of a system for the spatial characterisation of a CO2 pulsed laser beam is described. A CCD video camera and framestore interfaced to a personal computer are used to image the spatial intensity distribution produced by a CO2 pulse incident upon a temperature-dependent luminescent screen.
{"title":"Single-pulse two-dimensional CO2 laser beam profiling","authors":"N. C. Kerr, S. Clark, D. C. Emmony","doi":"10.1088/0022-3735/22/12/016","DOIUrl":"https://doi.org/10.1088/0022-3735/22/12/016","url":null,"abstract":"The construction and performance of a system for the spatial characterisation of a CO2 pulsed laser beam is described. A CCD video camera and framestore interfaced to a personal computer are used to image the spatial intensity distribution produced by a CO2 pulse incident upon a temperature-dependent luminescent screen.","PeriodicalId":16791,"journal":{"name":"Journal of Physics E: Scientific Instruments","volume":"1 1","pages":"1034-1036"},"PeriodicalIF":0.0,"publicationDate":"1989-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83115261","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 : 1989-12-01DOI: 10.1088/0022-3735/22/12/006
S. K. Howell, T. D. S. Hamilton, B. Turton
New modules are described that allow a single computer to control large systems of floating voltage supplies, which are programmed by providing serial RS232 data according to a specified protocol. This information is decoded to provide data for one or more DAC modules, each of which generate isolated, bipolar voltages which are then amplified to provide up to +or-300 V.
{"title":"Improvements to a system of computer-controlled voltage supplies","authors":"S. K. Howell, T. D. S. Hamilton, B. Turton","doi":"10.1088/0022-3735/22/12/006","DOIUrl":"https://doi.org/10.1088/0022-3735/22/12/006","url":null,"abstract":"New modules are described that allow a single computer to control large systems of floating voltage supplies, which are programmed by providing serial RS232 data according to a specified protocol. This information is decoded to provide data for one or more DAC modules, each of which generate isolated, bipolar voltages which are then amplified to provide up to +or-300 V.","PeriodicalId":16791,"journal":{"name":"Journal of Physics E: Scientific Instruments","volume":"24 1","pages":"994-997"},"PeriodicalIF":0.0,"publicationDate":"1989-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90785602","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 : 1989-12-01DOI: 10.1088/0022-3735/22/12/005
R. Horne, L. As, E. D. Kuyper, L. Hermans, B. Mulder
A method is described for making LiF constructions involving LiF-LiF and LiF-metal seals which are vacuum tight over a wide temperature range. As an application, rectangular LiF (001) surfaces have been assembled to form a flat channel which is connected to a copper vacuum flange. LiF machining was done using an ultrasonic technique. Mixtures of LiF and PbF2 were used as sealing agents throughout. The entire construction has been proved vacuum tight in the temperature range 78 K to 700 K.
{"title":"Temperature resistant and vacuum tight LiF connections","authors":"R. Horne, L. As, E. D. Kuyper, L. Hermans, B. Mulder","doi":"10.1088/0022-3735/22/12/005","DOIUrl":"https://doi.org/10.1088/0022-3735/22/12/005","url":null,"abstract":"A method is described for making LiF constructions involving LiF-LiF and LiF-metal seals which are vacuum tight over a wide temperature range. As an application, rectangular LiF (001) surfaces have been assembled to form a flat channel which is connected to a copper vacuum flange. LiF machining was done using an ultrasonic technique. Mixtures of LiF and PbF2 were used as sealing agents throughout. The entire construction has been proved vacuum tight in the temperature range 78 K to 700 K.","PeriodicalId":16791,"journal":{"name":"Journal of Physics E: Scientific Instruments","volume":"29 1","pages":"992-993"},"PeriodicalIF":0.0,"publicationDate":"1989-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76093514","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 : 1989-12-01DOI: 10.1088/0022-3735/22/12/020
L. Bañares, Á. G. Ureña
An oven design suitable for producing stable beams of highly reactive metals is reported. Its attraction is in its simplicity, low cost and versatility in molecular beam and atomic/molecular physics experiments involving highly reactive metals such as rubidium, caesium, etc. An application is described for the case of atomic caesium, where the metal is produced by the chemical reaction Ba(s)+CsCl(s) to BaCl(s)+Cs(v). One of the main advantages of the present design is the use of a thin-walled, stainless steel pipe, as crucible and heater simultaneously, which considerably simplifies its design. With respect to the experimental method, the simplicity in the loading, working and cleaning procedures compared with the use of pure metal should be noted.
{"title":"DESIGN NOTE: Simple oven design for highly reactive metal beam applications","authors":"L. Bañares, Á. G. Ureña","doi":"10.1088/0022-3735/22/12/020","DOIUrl":"https://doi.org/10.1088/0022-3735/22/12/020","url":null,"abstract":"An oven design suitable for producing stable beams of highly reactive metals is reported. Its attraction is in its simplicity, low cost and versatility in molecular beam and atomic/molecular physics experiments involving highly reactive metals such as rubidium, caesium, etc. An application is described for the case of atomic caesium, where the metal is produced by the chemical reaction Ba(s)+CsCl(s) to BaCl(s)+Cs(v). One of the main advantages of the present design is the use of a thin-walled, stainless steel pipe, as crucible and heater simultaneously, which considerably simplifies its design. With respect to the experimental method, the simplicity in the loading, working and cleaning procedures compared with the use of pure metal should be noted.","PeriodicalId":16791,"journal":{"name":"Journal of Physics E: Scientific Instruments","volume":"31 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1989-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74537545","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 : 1989-12-01DOI: 10.1088/0022-3735/22/12/017
K. Weir, B. Jennings
With highly asymmetric macromolecules, the observed optical activity depends upon the orientation of the molecules relative to the propagation direction of incident, linearly polarised light. Application of a pulsed electric field is accompanied by transient changes in the optical rotation. A laser-based apparatus has been assembled to measure these small changes with high precision. Details of the system are described along with the theoretical considerations upon which the design was established. The performance of the apparatus is demonstrated by measurements on solutions of the alpha -helical polypeptide poly- gamma -benzyl-L-glutamate in dichlorethane. The sensitivity of the measurements far exceeds all previous estimations of the rotatory powers associated with the alpha -helical axial directions.
{"title":"Apparatus for the measurement of electro-optical rotation changes in polymer solutions","authors":"K. Weir, B. Jennings","doi":"10.1088/0022-3735/22/12/017","DOIUrl":"https://doi.org/10.1088/0022-3735/22/12/017","url":null,"abstract":"With highly asymmetric macromolecules, the observed optical activity depends upon the orientation of the molecules relative to the propagation direction of incident, linearly polarised light. Application of a pulsed electric field is accompanied by transient changes in the optical rotation. A laser-based apparatus has been assembled to measure these small changes with high precision. Details of the system are described along with the theoretical considerations upon which the design was established. The performance of the apparatus is demonstrated by measurements on solutions of the alpha -helical polypeptide poly- gamma -benzyl-L-glutamate in dichlorethane. The sensitivity of the measurements far exceeds all previous estimations of the rotatory powers associated with the alpha -helical axial directions.","PeriodicalId":16791,"journal":{"name":"Journal of Physics E: Scientific Instruments","volume":"23 1","pages":"1037-1042"},"PeriodicalIF":0.0,"publicationDate":"1989-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74037546","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 : 1989-12-01DOI: 10.1088/0022-3735/22/12/015
W. Cao, A. Sprecher, H. Conrad
The procedures employed to measure the electroplastic effect resulting from the application of a high-density ( approximately 105 A cm-2) electric current pulse of 120 mu s duration during the plastic deformation of Nb in a uniaxial tension test are described in detail. Special attention is focused on eliminating the side effects of the current, such as result from Joule heating and the pinch effect. Thermally activated plastic-flow theory is employed to calculate the side contributions of thermal softening and load oscillations resulting from inertia effects. The electron-dislocation interaction contribution is derived for Nb and found to be about four times that for the FCC metals Al and Cu, and to increase with an increase in the plastic deformation rate just before the application of the current pulse.
详细描述了在单轴拉伸试验中，在Nb塑性变形过程中，应用高密度(约105 a cm-2)持续120 μ s的电流脉冲所产生的电塑性效应的测量程序。特别注意的是消除电流的副作用，如焦耳加热和捏效应的结果。采用热激活塑性流理论计算了由惯性效应引起的热软化和载荷振荡的侧贡献。推导了铌的电子位错相互作用贡献，发现其贡献约为FCC金属Al和Cu的四倍，并且随着施加电流脉冲前塑性变形率的增加而增加。
{"title":"Measurement of the electroplastic effect in Nb","authors":"W. Cao, A. Sprecher, H. Conrad","doi":"10.1088/0022-3735/22/12/015","DOIUrl":"https://doi.org/10.1088/0022-3735/22/12/015","url":null,"abstract":"The procedures employed to measure the electroplastic effect resulting from the application of a high-density ( approximately 105 A cm-2) electric current pulse of 120 mu s duration during the plastic deformation of Nb in a uniaxial tension test are described in detail. Special attention is focused on eliminating the side effects of the current, such as result from Joule heating and the pinch effect. Thermally activated plastic-flow theory is employed to calculate the side contributions of thermal softening and load oscillations resulting from inertia effects. The electron-dislocation interaction contribution is derived for Nb and found to be about four times that for the FCC metals Al and Cu, and to increase with an increase in the plastic deformation rate just before the application of the current pulse.","PeriodicalId":16791,"journal":{"name":"Journal of Physics E: Scientific Instruments","volume":"1 1","pages":"1026-1034"},"PeriodicalIF":0.0,"publicationDate":"1989-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87916388","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 : 1989-12-01DOI: 10.1088/0022-3735/22/12/008
M. Gunasekaran, Y. Jayalakshmi
A three-terminal capacitance bridge is developed for the measurement of the dielectric constant of lossy liquids. Using this modified ratio transformer bridge, the capacitance shunted by a resistance as low as 50 Omega is measured at 10 kHz. The capacitance error associated with the inductance of the connecting wire is compensated using the novel method of introducing an additional transformer to the existing ratio transformer bridge. Other sources of capacitance errors, such as the non-zero output impedence of the ratio transformer and the shield capacitances of the cables, are discussed.
{"title":"Ratio transformer bridge for the measurement of dielectric constant of lossy liquids","authors":"M. Gunasekaran, Y. Jayalakshmi","doi":"10.1088/0022-3735/22/12/008","DOIUrl":"https://doi.org/10.1088/0022-3735/22/12/008","url":null,"abstract":"A three-terminal capacitance bridge is developed for the measurement of the dielectric constant of lossy liquids. Using this modified ratio transformer bridge, the capacitance shunted by a resistance as low as 50 Omega is measured at 10 kHz. The capacitance error associated with the inductance of the connecting wire is compensated using the novel method of introducing an additional transformer to the existing ratio transformer bridge. Other sources of capacitance errors, such as the non-zero output impedence of the ratio transformer and the shield capacitances of the cables, are discussed.","PeriodicalId":16791,"journal":{"name":"Journal of Physics E: Scientific Instruments","volume":"22 1","pages":"1000-1004"},"PeriodicalIF":0.0,"publicationDate":"1989-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74698187","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 : 1989-12-01DOI: 10.1088/0022-3735/22/12/002
F. Jones, B. E. Welch
A model has been developed, and tested experimentally, to account for the apparent dependence of the effective cross-sectional area of pistons in gas-piston-gauge pressure standards on the particular gas with which the gauge is operated, in the absolute mode. The model treats a pressure drop or loss that depends on the pressure difference across the gauge (P1-P2), the fall rate of the piston, the density of the gas and the viscosity of the gas. The model was tested using helium, neon, argon, nitrogen and krypton, and several values of (P1-P2). An algorithm was developed for calculating the piston cross-sectional area. The experimental results confirmed the model and resulted in a reduction in measurement uncertainty arising from this effect by approximately one order of magnitude.
{"title":"Accounting for the effects of gas species on piston gauge calculated area: absolute mode","authors":"F. Jones, B. E. Welch","doi":"10.1088/0022-3735/22/12/002","DOIUrl":"https://doi.org/10.1088/0022-3735/22/12/002","url":null,"abstract":"A model has been developed, and tested experimentally, to account for the apparent dependence of the effective cross-sectional area of pistons in gas-piston-gauge pressure standards on the particular gas with which the gauge is operated, in the absolute mode. The model treats a pressure drop or loss that depends on the pressure difference across the gauge (P1-P2), the fall rate of the piston, the density of the gas and the viscosity of the gas. The model was tested using helium, neon, argon, nitrogen and krypton, and several values of (P1-P2). An algorithm was developed for calculating the piston cross-sectional area. The experimental results confirmed the model and resulted in a reduction in measurement uncertainty arising from this effect by approximately one order of magnitude.","PeriodicalId":16791,"journal":{"name":"Journal of Physics E: Scientific Instruments","volume":"97 1","pages":"981-985"},"PeriodicalIF":0.0,"publicationDate":"1989-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76097673","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 : 1989-12-01DOI: 10.1088/0022-3735/22/12/019
R. Koul, H. S. Vora, M. N. Kumbhare, Y. Tyagi
A digital method for the accurate measurement and display of speed and speed variation of low-speed drives is described. The method is based on the use of an incremental shaft encoder in association with an accurate crystal oscillator. The speed variations can be detected to within one thousandth of the time taken for one revolution of the drive shaft. The speed variation, along with its time of occurrence, is stored on the RAM and can be printed by a serial printer or can be stored on the hard disc of a personal computer.
{"title":"A microprocessor-based method for the measurement of speed and speed variation of low-speed drives","authors":"R. Koul, H. S. Vora, M. N. Kumbhare, Y. Tyagi","doi":"10.1088/0022-3735/22/12/019","DOIUrl":"https://doi.org/10.1088/0022-3735/22/12/019","url":null,"abstract":"A digital method for the accurate measurement and display of speed and speed variation of low-speed drives is described. The method is based on the use of an incremental shaft encoder in association with an accurate crystal oscillator. The speed variations can be detected to within one thousandth of the time taken for one revolution of the drive shaft. The speed variation, along with its time of occurrence, is stored on the RAM and can be printed by a serial printer or can be stored on the hard disc of a personal computer.","PeriodicalId":16791,"journal":{"name":"Journal of Physics E: Scientific Instruments","volume":"4 1","pages":"1044-1045"},"PeriodicalIF":0.0,"publicationDate":"1989-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84903832","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 : 1989-12-01DOI: 10.1088/0022-3735/22/12/013
M. Costes, C. Naulin, G. Dorthe, G. Daleau, J. Joussot‐Dubien, C. Lalaude, M. Vinckert, A. Destor, C. Vaucamps, G. Nouchi
A pulsed crossed supersonic molecular beam apparatus is described which is suitable for the determination of state-to-state reactive cross sections of ground state refractory atoms with oxidant molecules. The unique aspect of the instrument is its metal-atom beam, in which the atoms are generated by laser ablation of the corresponding solid and are entrained in neutral gases which expand supersonically at the exit of a pulsed nozzle. The peak intensities from this source can exceed the intensities obtainable with a conventional metal-oven effusive source by orders of magnitude for the more refractory elements. Other characteristics, such as a truly tunable velocity range from 600 to 3400 m s-1 associated with a velocity spread between 20 and 10% FWHM, constitute improvements over such conventional sources. Evidence of this superiority is given by comparative experiments on the reaction dynamics of carbon and aluminium. The versatility of the pulsed metal beam, which can accommodate metals, including the most refractory elements, is of great promise for future experiments in this area.
介绍了一种适用于测定基态难熔原子与氧化分子的状态间反应截面的脉冲交叉超音速分子束装置。该仪器的独特之处在于它的金属原子束，其中原子是由相应固体的激光烧蚀产生的，并被夹在脉冲喷嘴出口处以超音速膨胀的中性气体中。对于更难熔的元素，该源的峰值强度可以超过传统金属炉热流源的强度，其数量级更高。其他特性，如真正可调的速度范围从600到3400 m s-1，速度分布在20%到10%的FWHM之间，构成了对此类传统源的改进。碳和铝的反应动力学对比实验证明了这种优越性。脉冲金属束的多功能性，它可以容纳金属，包括最难熔的元素，在这一领域的未来实验中有很大的希望。
{"title":"A pulsed crossed supersonic molecular beam apparatus to study the dynamics of refractory atom reactions","authors":"M. Costes, C. Naulin, G. Dorthe, G. Daleau, J. Joussot‐Dubien, C. Lalaude, M. Vinckert, A. Destor, C. Vaucamps, G. Nouchi","doi":"10.1088/0022-3735/22/12/013","DOIUrl":"https://doi.org/10.1088/0022-3735/22/12/013","url":null,"abstract":"A pulsed crossed supersonic molecular beam apparatus is described which is suitable for the determination of state-to-state reactive cross sections of ground state refractory atoms with oxidant molecules. The unique aspect of the instrument is its metal-atom beam, in which the atoms are generated by laser ablation of the corresponding solid and are entrained in neutral gases which expand supersonically at the exit of a pulsed nozzle. The peak intensities from this source can exceed the intensities obtainable with a conventional metal-oven effusive source by orders of magnitude for the more refractory elements. Other characteristics, such as a truly tunable velocity range from 600 to 3400 m s-1 associated with a velocity spread between 20 and 10% FWHM, constitute improvements over such conventional sources. Evidence of this superiority is given by comparative experiments on the reaction dynamics of carbon and aluminium. The versatility of the pulsed metal beam, which can accommodate metals, including the most refractory elements, is of great promise for future experiments in this area.","PeriodicalId":16791,"journal":{"name":"Journal of Physics E: Scientific Instruments","volume":"16 1","pages":"1017-1023"},"PeriodicalIF":0.0,"publicationDate":"1989-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83455128","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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