摘要:

A probe has been developed to measure the flux of electrons traveling in a direction opposite to that of the ions in a high‐energy ion beam. The probe is of the Langmuir type and will ideally obey the Mott‐Smith, Langmuir theory for positive probe potentials. With this probe the albedo electron flux has been measured in a beam of 1‐ to 2‐kV cesium ions.

ISSN:0034-6748    

DOI:10.1063/1.1717777

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

A resistance heated source is described which is capable of evaporating refractory materialsin vacuo. Film thickness uniformity and deposition efficiency are improved through the use of a converging‐diverging nozzle at the crucible outlet. The source also features a double‐wall cylindrical graphite heater configuration which facilitates the reduction of heat losses and copper to graphite electrical connectors capable of operating over a large temperature range.

ISSN:0034-6748    

DOI:10.1063/1.1717778

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

A triangular voltage is integrated and the output current fed to a vibrator so as to produce linearly changing velocities. The output voltage of a velocity pickup coil is then compared to the triangular input voltage in a negative feedback arrangement which further linearizes the velocity.

ISSN:0034-6748    

DOI:10.1063/1.1717779

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

Full magnetic hysteresis loops, obtained by underdamped discharge of a capacitor through a solenoid, were used to study loop distortion produced by eddy currents, protracted or delayed flux changes, and instrumental errors. Pulsed field loops obtained for &ggr;Fe2O3powder with 14 000‐Oe maximum field closely overlapped loops obtained statically with one‐tenth this field amplitude. In contrast, an apparent coercive force of 110 Oe was obtained with the pulsed field method for a sample of 0.158‐cm‐diam iron wire having a static coercive force of 3.6 Oe. Almost two‐thirds of the observed coercive force was attributable to eddy currents. Instrumental errors were less than 10 Oe and the residual coercive force was identified with the protracted flux change which has sometimes been attributed to magnetic viscosity in iron. Instrumental difficulties involved delay, distortion, or imperfect integration of high frequency components in detector coil signals, cumulative integration errors associated with low frequency components from nearly saturated specimens, and pickup. The detection system described is also suitable for quasistatic (slowly traced hysteresis loop) measurements.

ISSN:0034-6748    

DOI:10.1063/1.1717780

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

A low temperature double beam absorption cell designed specifically for the Beckman DK, DK‐1, and DK‐2 is described. It may be used down to at least −196°C in quantitative measurements of visible and ultraviolet absorption spectra of liquid or rigid glass solutions. A detailed listing of low temperature glasses and low temperature solvents which might be used in conjunction with the cell is given. In addition, some possible cooling systems are included.

ISSN:0034-6748    

DOI:10.1063/1.1717781

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

An expression is derived for the flux of multiply scattered charged particles emerging from a square‐edge collimating slit for a parallel beam at normal incidence. Full allowance is made for the continuous energy loss in the slit material, and the results are compared with those from Courant's theory. The effective increase in aperture is calculated for 50‐MeV protons on elements throughout the periodic table and the optimum materials for collimators are discussed. A computation of the origin on the collimator face of the slitscattered flux from 50‐MeV protons on copper shows that over 90% originate in the first 0.025 cm from the edge, when all energies are detected, and in less than 0.01 cm for energies above 37.5 MeV. The energy distribution is calculated as a function of the angular range accepted. The projected angle distribution, integrated over all energies, is found to have a maximum at about 1.5° for carbon, 4° for copper, and 7° for lead, with 50‐MeV incident protons. The higher energy slit‐scattered protons are shown to peak at smaller angles. Approximations in the theory are discussed and the results compared with those from Monte Carlo calculations by Becker and from the work of O¨vera˚s.

ISSN:0034-6748    

DOI:10.1063/1.1717782

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

A general discussion is given of the main factors affecting the successful attainment by induction melting of stable floating zones in a wide variety of materials. The emphasis is on poor conductors, for which the problems involved can usually be solved. Details of the apparatus and procedures used in the floating zone growth of NaCl, KCl, KBr, KI, and LiF single crystals are given, as well as specifications of the quality of such crystals as determined by various tests.

ISSN:0034-6748    

DOI:10.1063/1.1717783

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

The frequent use of Langmuir probes in the determination of electron temperatures and number densities in plasmas makes it desirable to have rapid methods of data reduction. This paper describes a simple and accurate instrument for carrying this out without the necessity of using logarithmic amplifiers or oscilloscope displays. Apart from its advantages in ease of construction, its calibration is particularly simple and drift‐free. In operation, the device samples the probe characteristic at two values of current, and yields a numerical value for the electron temperature on a meter. Linearity of the characteristic is examined by varying the sampling currents. Provisions are made for ion current to be compensated and measured, and for the electron saturation current to be estimated.

ISSN:0034-6748    

DOI:10.1063/1.1717784

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

A decimal coded binary counter is described which employs four tunnel diodes to achieve ten stable states and a transistor circuit for reset amplification and readout of the carry. The tunnel diodes must satisfy certain relationships between their peak and valley currents and final voltages. The principle of operation is discussed and the circuit of the decade counter described. The paper presents the required conditions for the diode parameters and gives experimental results obtained on a laboratory model.

ISSN:0034-6748    

DOI:10.1063/1.1717785

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

A detailed description of a cylindrical reflection cavity operating in the TE112mode in the X band is given. The special features of the cavity design are provision for the passage of a beam of light through the region of maximum magnetic field in any direction perpendicular to the axis of the cavity, and an integral crystal mounting arrangement that allows optical alignment of the crystal around two perpendicular axes while the cavity is immersed in a liquid helium bath under reduced pressure.

ISSN:0034-6748    

DOI:10.1063/1.1717786

出版商:AIP    

年代:1962

数据来源: AIP