摘要:

The transmission characteristics of spherical plate electrostatic analyzers for external sources are studied. Transmission as a function of particle point of incidence, angle of incidence, and kinetic energy, and of analyzer plate geometry (central angle and radii of curvature) and plate potentials, is determined analytically and graphically. Our method (which assumes that the ratio of plate spacing to mean radius is small) uses derived relationships between these parameters and the position of the center of the particle's trajectory, which trajectory is approximated by a circular arc. For a fine incident beam of particles, angular resolution at mean transmitted energy and energy resolution at normal incidence are independent of the point of incidence; the angular resolution is moreover a constant and the energy resolution varies linearly with the mean energy. The area of energy‐angle transmission diagrams is likewise independent of point of incidence. Energy and angle response functions for diffuse beams of particles are derived semi‐empirically. The energy response function (integrated over angle) has the same FWHM as the function for a fine beam incident normally. The angle response function (integrated over energy) has the same FWHM as the function for a fine beam at appropriate fixed energy. Theoretical results for fine beams are compared with experiment and agree well. A practical instrument, specifically for satellite use but suitable for the laboratory, is also described.

ISSN:0034-6748    

DOI:10.1063/1.1720771

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

The average charge of insulating polymer particles has been measured as a function of particle size and tribo‐electric treatment of the sample. Particle sizes were in the range 5–30 &mgr;; the particle size distribution was determined by means of a light microscope. The charges were measured with an electrometer: the particles were supported on a photoconducting layer and the electrometer measurements were made in the dark and in the light; thus, the position of the ground plane was effectively varied, and by comparing the two sets of results the average distance of the particle charge from the photoconductor surface could be inferred. Average charges as large as 4×105electrons per particle were measured.

ISSN:0034-6748    

DOI:10.1063/1.1720772

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

A new technique is discussed for the measurement of the properties of anisotropic magnetic materials. The basis of the technique is the harmonic analysis of the signal induced in a pick‐up loop when the anisotropic material is immersed in a spatially rotating magnetic field. It is shown that the harmonics which are generated are related in a simple way to the Fourier coefficients of the anisotropy energy. High sensitivity is achieved through use of a lock‐in detector for the harmonic analysis. Apparatus is described in which the magnetic field rotates at 500 Hz with an amplitude up to 50 Oe. This apparatus can detect a magnetic moment of 10−7emu and equivalent torque of 10−6dyne·cm. Illustrative data obtained from a thin Permalloy film (moment of 5×10−3emu) are given, in which the first three Fourier coefficients of the anisotropy energy are 817, <18, and <1.5 erg/cm3. The absolute accuracy of the first coefficient is about 2%, while the reproducibility of this measurement is better than ½%.

ISSN:0034-6748    

DOI:10.1063/1.1720773

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

This paper describes a modification of the back reflection Laue camera in which the film is placed on a conical surface, thereby providing a direct stereographic projection of the crystal without the use of nets or the measurement of angles. A larger number of reflections is also obtained for this camera as compared with the flat camera. A quantitative discussion of the geometry of the diffraction patterns obtainable with this camera is presented.

ISSN:0034-6748    

DOI:10.1063/1.1720774

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

The design of an ac superconducting solenoid capable of producing oscillatory magnetic fields having peak‐to‐peak amplitudes as large as 1000 G at frequencies up to 500 Hz with only moderate dissipation is discussed. It is shown that a simple, inefficient coil geometry (thin solenoid) is suitable. Tests with an ac superconducting solenoid used as a modulation coil in a 60 kG superconducting magnet are described. Results indicate that the performance of copper at 4.2°K is far surpassed by Nb‐25% Zr over a wide range of operating conditions.

ISSN:0034-6748    

DOI:10.1063/1.1720775

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

The Volta effect severely limits the use of conventional plate field mills in detecting weak electric fields. A modified field mill is described which eliminates the influence of the Volta noise on the measurement. This is achieved by changing the distance between the electrodes during the operation of the instrument. The direction of the field measured is indicated without additional instrumentation. After one initial calibration, the accuracy obtained with the instrument was 1 Vm−1over a time period of months.

ISSN:0034-6748    

DOI:10.1063/1.1720776

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

The design of a small, electromagnetically driven impact apparatus is described. The unit was designed as a laboratory unit to compact small samples of powdered materials to high density. A capacitor bank energy source is discharged into a solenoid coil. The resulting field is used to accelerate a plunger which impacts on the punch and die assembly containing the material to be compacted.

ISSN:0034-6748    

DOI:10.1063/1.1720777

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

A method is outlined whereby the Sonagraph is provided with storage oscilloscope display using the Tektronix 564 oscilloscope.

ISSN:0034-6748    

DOI:10.1063/1.1720778

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

In sampling reflected shock waves directly into a time‐of‐flight mass spectrometer, one of the crucial problems is to remove the sampled gas from the ion source. Preliminary experiments with the mass spectrometer flight tube and shock tube axis collinear showed that more pumping speed was required to cope with the sample jet. The required pumping rate, estimated from the rate of pressure decrease on the high pressure side of the sampling orifice, was of the order of 105liter/sec at 10−6Torr. A cryosorption pump was built which employed a freshly evaporated molybdenum film at liquid nitrogen temperature as the pumping surface. The shock tube and flight tube axes were placed perpendicular and the sample beam passed through the ionizing electron beam into the cryosorption pump. This arrangement proved satisfactory, and results on the decomposition of CS2were in reasonable agreement with those of other workers.

ISSN:0034-6748    

DOI:10.1063/1.1720779

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

A wide band, variable frequency nuclear magnetic resonance spectrometer is described for use with either a crossed‐coil induction probe in the frequency range 2 to 40 MHz or a parallel T rf bridge from 2 to 90 MHz. A novel use of simple rf circuits is described wherein the receiver amplifier has useful gain to 95 MHz and the transmitter amplifier has useful gain to 45 MHz. A simple modification of the Varian Associates 8 to 16 MHz induction probe for use with this circuit to 40 MHz is described. Sensitivity of the instrument with both the probe and bridge compares most favorably with a commercial induction spectrometer. The circuit is essentially free of microphonic noise.

ISSN:0034-6748    

DOI:10.1063/1.1720780

出版商:AIP    

年代:1967

数据来源: AIP