Showing papers in "Journal of Physics E: Scientific Instruments in 1979"
TL;DR: In this paper, the authors present a review of fluxgate magnetometry based on a survey of the literature and on the work of the author and colleagues, and an evaluation of the merit of the different types of sensors is made based on the sensor geometry.
Abstract: Presents a review of fluxgate magnetometry based on a survey of the literature and on the work of the author and colleagues. The theory is outlined and an evaluation of the merit of the different types of sensors is made based on the sensor geometry. The design of a second-harmonic feedback magnetometer is discussed with respect to sensor configuration, frequency response, noise, offset, temperature dependence and long-term stability. Examples of the parameters are compiled from the literature and some new results on the long-term stability are presented.
421 citations
TL;DR: In this paper, an improved version of the Hesse-rubartsch method was applied to the evaluation of the hyperfine field distribution in an amorphous Fe79.5Si1.5B19 alloy at room temperature.
Abstract: An improved version of the Hesse-Rubartsch method is described. This method is applied, together with an adapted peak shape, to the evaluation of the hyperfine field distribution in an amorphous Fe79.5Si1.5B19 alloy at room temperature. The detailed structure of this distribution is discussed.
417 citations
TL;DR: In this article, a diffusing screen coupled to a light guide is used to obtain an output beam with an exceptionally flat and uniform intensity distribution for the pulsed annealing of materials using laser radiation.
Abstract: With the advent of methods for the pulsed annealing of materials using laser radiation, it has become increasingly important to achieve good beam uniformity. The authors describe a device based upon a diffusing screen coupled to a light guide which accepts a multimode beam directly from a laser and, irrespective of input beam inhomogeneities, yields an output beam with an exceptionally flat and uniform intensity distribution. The optical efficiency of the device is high and the output radiation power density can be controlled by adjusting diffuser design parameters. Deleterious speckle patterns in the output beam can be virtually eliminated.
146 citations
TL;DR: In this paper, the authors examined the problems of X-ray flash production and its applications, similar to those of continuous X-radiation, and showed that the flash time is mostly between 10 ns and 1 mu s.
Abstract: The author examines the problems of X-ray flash production and its applications, similar to those of continuous X-radiation. Special problems are the fast production of high X-ray intensities to produce detectable radiation and the high-voltage and high-current discharge circuits required. Anode voltages from some 10 kV to about 1 MV and currents up to 10 kA are normal for laboratory equipment, but 100 MV and 1 MA are possible. The flash time is mostly between 10 ns and 1 mu s. Cineradiography with frame rates up to 106 pictures s-1 can be achieved.
130 citations
TL;DR: In this article, the adverse influence of fringing fields on the beam trajectories can be reduced, while retaining narrow apertures at the entrance and exit planes of the deflector and without changing the deflection angle, as would be required by the Herzog correction.
Abstract: The entrance and exit regions of 127 degrees cylindrical or 180 degrees spherical electron spectrometers with real apertures are approximated by a shielded parallel plate capacitor By employing a resistor network, the fringing field resulting from a new arrangement of shielding electrodes is measured It is shown that the adverse influence of fringing fields on the beam trajectories can be reduced, while retaining narrow apertures at the entrance and exit planes of the deflector and without changing the deflection angle, as would be required by the Herzog correction
89 citations
TL;DR: In this paper, the design procedure of a "simulated" spherical electron spectrometer is described, which has spherical equipotentials in the region of the beam trajectories, whereas its electrodes are non-spherical.
Abstract: The design procedure of a 'simulated' spherical electron spectrometer is described. This device has spherical equipotentials in the region of the beam trajectories, whereas its electrodes are non-spherical. The electron optical properties of the new device are very close to those of a spherical spectrometer. Its geometric width, however, is only about one-third that of a conventional hemispherical spectrometer. Because of its simple electrode structure, gridded or corrugated electrodes can be used easily to suppress background electrons. A prototype of the new instrument was employed as an electron monochromator. An energy spread of less than 25 meV was achieved.
88 citations
TL;DR: In this paper, an inexpensive apparatus for surface area measurement using krypton with a lower limit of 0.001 m2 has been developed, which is made simple by the use of an MKS Baratron pressure gauge and a constant-volume system.
Abstract: An inexpensive apparatus for BET (Brunauer, Emmett and Teller) surface area measurement using krypton with a lower limit of 0.001 m2 has been developed. Operation is made simple by the use of an MKS Baratron pressure gauge and a constant-volume system.
67 citations
TL;DR: The instrument described in this article is used to locate and study various noise sources and other disturbances, which would restrict signal perceptibility, from an analysis of these disturbances, the demands on apparatus components are estimated.
Abstract: The instrument described is used to locate and study various noise sources and other disturbances, which would restrict signal perceptibility. From an analysis of these disturbances, the demands on apparatus components are estimated. Some constructional details are given, as well as suggestions for improvement aimed at a future interferometer of increased base length, with the prospect of successful operation.
56 citations
TL;DR: In this article, a redesigned oscillating-cylinder viscometer for low-viscosity fluids up to 1200 degrees C is described, where absolute viscosities are calculated from logarithmic decrements obtained by time measurements using fixed photodetectors.
Abstract: A redesigned oscillating-cylinder viscometer for low-viscosity fluids up to 1200 degrees C is described. Absolute viscosities are calculated from logarithmic decrements obtained by time measurements using fixed photodetectors. The digital data acquisition system is computer-facilitated and highly automated. The cylinder may be a solid disc submerged in the liquid, or a cup containing highly volatile melts. The viscosity of molten NaCl is determined over the temperature range 810-930 degrees C.
46 citations
TL;DR: In this paper, a time-of-flight system for the analysis of crossed molecular beam scattering is described, which is based on a minicomputer interface and can operate in both the cross-correlation and conventional modes.
Abstract: A time-of-flight system for the analysis of crossed molecular beam scattering is described, which is based on a minicomputer interface and can operate in both the cross-correlation and conventional modes. The interface maintains the synchronisation of chopper disc rotation and channel advance indefinitely in the cross-correlation method and can acquire data in phase with the beam modulation in both methods. The shutter function of the cross-correlation method is determined and the deconvolution analysis of the data is discussed.
44 citations
TL;DR: In this paper, two pneumatically operated changeover valves, of a new design, with electrically heated capillaries in the dual-inlet system, which reduce the instrumental effects of this system to a negligible level.
Abstract: The system described incorporates two pneumatically operated changeover valves, of a new design, with electrically heated capillaries in the dual-inlet system, which reduce the instrumental effects of this system to a negligible level. The changeover valves show many advantages such as high accuracy of closure, fast establishment of steady conditions after switching, simple construction and automatic control. Information on installation of stainless steel capillaries is also included.
TL;DR: The overall objective of the Home Office Police Scientific Development Branch is the improvement in operational efficiency of the British police forces, by the study and planning of new methods and the development of special-purpose equipment.
Abstract: The overall objective of the Home Office Police Scientific Development Branch is the improvement in operational efficiency of the British police forces, by the study and planning of new methods and the development of special-purpose equipment. Scientific staff work closely with senior police officers on a wide variety of subjects. For example, systems research projects include studies of command and control, traffic resource allocation, and major incident record handling, while other groups carry out research on fingerprints and on facial recognition. Equipment work encompasses assessment and development of an extremely wide range of hardware, and four examples are described, namely remote observation, night vision, location of hidden objects, and intruder detection.
TL;DR: The continuous adiabatic method described in this article yields a graphical representation of the inverse specific heat as a function of temperature, and the principal advantages are simple construction high-level electrical signals, small samples (about 1 g), good behaviour through first-order transitions, low additional masses, low cost and complete automation.
Abstract: The continuous adiabatic method described yields a graphical representation of the inverse specific heat as a function of temperature. The principal advantages are: simple construction high-level electrical signals, small samples (about 1 g), good behaviour through first-order transitions, low additional masses, low cost and complete automation.
TL;DR: In this paper, a microwave discharge source with a dilute mixture of oxygen molecules in excess helium or neon buffer gas at high pressure (below about 2.6*104 Pa) is described.
Abstract: Describes the design and construction of a microwave discharge source which operates with a dilute mixture of oxygen molecules in excess helium or neon buffer gas at high pressure (below about 2.6*104 Pa). Seeded supersonic beams of oxygen atoms are produced with Mach numbers M>or approximately=5 and translational energies E=33.6 kJ mol-1 for helium buffer gas and E=13.5 kJ mol-1 for neon. Oxygen atom beam fluxes of around 5*1017 atoms sr-1 s-1 are obtained using helium buffer gas, and slightly lower fluxes of about 1*1017 atoms sr-1 s-1 with neon. A supersonic beam of chlorine atoms with similar characteristics has been produced by discharge of a dilute mixture of chlorine molecules in helium buffer gas.
TL;DR: A survey of the various types of transducers that are available commercially for measuring displacements of less than 50 mm is presented in this paper, where their performances are compared and different forms of signal processing and output display are also discussed.
Abstract: A survey is made of the various types of transducer that are available commercially for measuring displacements of less than 50 mm; their performances are compared. The various types of mechanical coupling and conversion that generally limit transducers performance are also compared. The different forms of signal processing and output display are also discussed.
TL;DR: A description of the program software written for the computer and methods presented to enable both the sweep speed and vertical deflection factor settings of the sampling oscilloscope to be calibrated to a precision of greater than 0.5%.
Abstract: A description of the program software written for the computer is given and methods are presented to enable both the sweep speed and vertical deflection factor settings of the sampling oscilloscope to be calibrated to a precision of greater than 0.5%. Details are provided of refinements made to the extrapolation method of time-referencing the data. The necessity of using a reference waveform and the advantage of using one particular configuration of the air lines in the coaxial line system are then discussed. Experimental details are given and it is shown that experiments yielding 50 frequency points can be performed typically in less than 17 min.
TL;DR: A review of the known effects of sputtering on film deposition can be found in this article. But this can be done controllably only by careful attention to all the possible effects that can occur.
Abstract: Substrates for film deposition can be cleaned and/or modified in a variety of ways by various sputtering techniques, but this can be done controllably only by careful attention to all of the possible effects that can occur. In this review the known effects are summarised. Some of the system configurations that can be used are described. The physical and chemical sputtering effects are emphasised. These include rates of material removal and recontamination, backscattering, redeposition, trenching, faceting, cone formation, formation of altered surface layers, dissociation of compounds, diffusion, sublimation, ion implantation, crystallographic damage and radiation damage.
TL;DR: In this article, an improved low-energy electron spectrometer using concentric hemispheres with a grid retarding field is presented, where a triple-cylinder electrostatic lens, with the middle potential higher than the outer potentials, can perform a preselection.
Abstract: An improved low-energy electron spectrometer using concentric hemispheres with a grid retarding field is presented. Emphasis is given to the means by which a triple-cylinder electrostatic lens, with the middle potential higher than the outer potentials, can perform a preselection. This improves simultaneously the collection efficiency and the intrinsic signal-to-noise ratio of the spectrometer. The operating mode of both the input lens and hemispheres is invariable over the energy range 0-1500 eV. The comparison of Auger transition probabilities is therefore possible. The variations of the relative collection efficiency and instrumental broadening as functions of the detection energy inside the deflectors are shown on characteristic curves. Good-quality Auger spectra of molybdenum and silicon carbide are given as examples on the electron distribution curves N(E)=f(E), obtained with a very small current density (10-3 A cm-2) at relatively low primary energy (1500 eV).
TL;DR: In this paper, the authors describe the construction of the probe, the calibration procedure, the effects of Reynolds number and the sensitivity of the pitch of the instrument to pitch in free-stream flow.
Abstract: The probe was designed as a sensor of the measurement of static pressure acting on the surface of a building but the design also permits it to be used in free-stream flow. Details are given of the construction of the probe, the calibration procedure, the effects of Reynolds number and of the sensitivity of the probe to pitch.
TL;DR: In this paper, a technique for measuring the dielectric properties of materials in the range from 1 MHz to 1.3 GHz is described, and modifications in commercially available network analyser system which will permit increased accuracy and will simultaneously take into account errors arising from nonlinearities of the network analyzer are also presented.
Abstract: The technique is used for measuring the dielectric properties of materials in the range from 1 MHz to 1.3 GHz is described. Modifications in the commercially available network analyser system which will permit increased accuracy and will simultaneously take into account errors arising from nonlinearities of the network analyser are also presented. The technique is demonstrated for both low- and high-loss liquids, such as carbon tetrachloride, propanol and butanol.
TL;DR: In this article, the Bridgman method of opposed anvils was used for resistivity measurements on two samples and a lead manometer, and a new sealing technique was proposed to support the tapered portion of the anvil and the use of a metal gasket.
Abstract: The device described is based on the Bridgman method of opposed anvils but employs a new sealing technique. This allows the support of the tapered portion of the anvils and the use of a metal gasket in a cell with electrical wiring. The cell was successfully used for four-terminal resistivity measurements on two samples and a lead manometer.
TL;DR: In this article, a typical system for high-vacuum evaporation is described and three methods of heating the target material to evaporating temperatures are discussed (i.e., resistance heating, induction heating and heating by means of electron bombardment).
Abstract: A typical system for high-vacuum evaporation is described and the three methods of heating the target material to evaporating temperatures are discussed (i.e. resistance heating, induction heating and heating by means of electron bombardment). Various electron bombardment configurations are compared in detail. The relative merits of various thickness measuring techniques are described. Stages in the fabrication and mounting of self-supporting foils are described, with emphasis given to the preparation of thin self-supporting carbon foils used as target backings and stripper foils. Various target backings, and the merit of the more generally used release agents are described. The preparations of more difficult elemental targets are discussed, and a comprehensive list of the common targets is presented.
TL;DR: In this article, the improved psychrometer is constructed from high-thermal-conductivity materials to minimize temperature gradients within it, and it is symmetrically constructed with respect to the porous windows where moisture exchange with the soil occurs.
Abstract: The improved psychrometer is constructed from high-thermal-conductivity materials to minimise temperature gradients within it. To minimise errors from condensation on the psychrometer, it is symmetrically constructed with respect to the porous windows where moisture exchange with the soil occurs. Zero offset of the new units is reduced by more than an order of magnitude compared with previous versions and measurement errors due to temperature gradients are less than one-third the value for the best designs previously available.
TL;DR: In this paper, a beam-scanning system for a merged electron-ion beam experiment is described, which is used to determine the horizontal and vertical beam profiles and the form factors at three different locations along the axis of the beams.
Abstract: A beam-scanning system for a merged electron-ion beam experiment is described. This system is used to determined the horizontal and vertical beam profiles and the form factors at three different locations along the axis of the beams. Design details of the wedge-shaped scanners and the electronic circuit for obtaining beam profiles and form factors are described. The form factor derivation for merged beams is given and an expression in terms of measured quantities is derived.
TL;DR: In this paper, a review of the development and performance of PPEMs is presented, including characteristics such as gain, pulse height distribution, timing and long-term operation, and some general considerations concerning fabrication processes are presented together with a specific design of a detector array.
Abstract: A review is made of the development and performance. A simple theory necessary to understand the principles of operation is outlined. Characteristics such as gain, pulse height distribution, timing and long-term operation are summarised. Some general considerations concerning fabrication processes are presented together with a specific design of a detector array. A novel structure of a PPEM exhibiting self-scanning x-position sensitivity is also described. A general comparison with the channel electron multiplier shows that the two devices generally operate in a similar way but differ in saturation behaviour.
TL;DR: In this article, a thermovoltage-controlled circuit is described which, in connection with a programmable power supply, permits controlled heating and flashing of specimens in ultra-high vacuum.
Abstract: A thermovoltage-controlled circuit is described which, in connection with a programmable power supply, permits controlled heating and flashing of specimens in ultra-high vacuum. With resistance-heated specimens the heating rate is variable over a wide range (2-50K s-1). Although the circuit is designed for applications in flash desorption spectroscopy, it can be used for continuously adjusting sample temperatures up to 1500K.
TL;DR: In this paper, a modified laser Doppler anemometer set-up and a commercial digital correlator are used to measure velocity auto-and cross-correlation functions directly.
Abstract: By use of a modified laser Doppler anemometer set-up and a commercial digital correlator, velocity auto- and cross-correlation functions are measured directly. These functions determine time scales of velocity fluctuations as well as their first- and second-order statistics. The technique is demonstrated with flows of perfect time periodicity, i.e. Taylor vortices between rotating cylinders, and of a highly random nature, i.e. turbulence in an open flow channel.
TL;DR: A digital minicomputer has been interfaced with a scanning electron microscope, and programmed to control the excitations of the objective lens and the stigmator of the microscope.
Abstract: A digital minicomputer has been interfaced with a scanning electron microscope, and programmed to control the excitations of the objective lens and the stigmator of the microscope. The electron beam is scanned by a digital scan generator and the digitised video signal is used for computations. To focus the microscope, a parameter related to the 'sharpness' of the image is maximised, and to set the stigmator, the directional information in the above- and below-focus images is used.
TL;DR: In this article, an electron mirror interference microscope for 25 keV electrons is presented, where two band-shaped coherent partial waves, each about 5 mu m in width and with a transverse separation of about 10 mu m, are reflected at an electrostatic electron mirror.
Abstract: In an electron mirror interference microscope for 25 keV electrons, i.e. with a wavelength of 0.008 nm, two band-shaped coherent partial waves, each about 5 mu m in width and with a transverse separation of about 10 mu m, are reflected at an electrostatic electron mirror. The small deviations from ideal smoothness of the mirror result in small deviations from homogeneity of the electrostatic field in front of its surface and hence in small phase variations in the reflected electron waves. The reflected partial waves are then superimposed by means of an electron optical biprism. They form an interference pattern consisting of a system of fringes. An analysis of the deviation of the fringes from parallel straight lines permits the determination of the deviation from ideal smoothness of the mirror surface.
TL;DR: A review of experimental techniques and instrumental design of field ionisation and desorption sources is given in this paper, with a comprehensive account of the various types of ion emitter.
Abstract: A review is given of experimental techniques and instrumental design of field ionisation and desorption sources. Special emphasis is laid on a comprehensive account of the various types of ion emitter. Different sample-loading techniques are also discussed. Automatic FD emitter-heating devices and laser-assisted FD are also described.