摘要:

The problem of space‐charge limited currents in a diode with plane‐parallel electrodes is considered for the case where space‐charge limitations are counteracted by the introduction of ions at the cathode. The ``no‐collision'' approximation is used, in which inelastic and short‐range elastic collisions are neglected, and each particle interacts with the Coulomb field of all the other particles. The electrostatic potential is determined, in a self‐consistent manner, from Poisson's equation. The equations are simplified by transforming to reduced variables in a manner described by Langmuir and others. The first integrations of Poisson's equation are given for the six most important cases. The first of these has been reported by P. L. Auer, but rigorous analysis of the remaining five cases has not been previously reported. Analytical solution of the first‐order differential equations derived is impossible. Numerical solutions have been obtained for illustrative purposes on the IBM‐704 computer. More complete numerical solutions are being compiled.

ISSN:0021-8979    

DOI:10.1063/1.1729001

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

A hollow cathode discharge (HCD) is described that produces a highly ionized steady‐state plasma (ne≈1013−1014/cm3) at a temperature 1–10 eV, in a volume as large as 104cm3, with background neutral gas density ≈1013/cm3. The HCD is generated by the prescription: gas flow (H2, He, A, or N2) 0.05–2 cc STP/sec through a refractory metal hollow cathode tube into a vacuum; any anode; 20–200 V dc applied. An axial induction 100–1000 G is used to collimate the discharge and to aid in starting by rf excitation. The HCD runs from the cathode interior, deep enough thatp0d≈1 cm×mm Hg. Current range is 2.0–300 A. Various electrode configurations and a wide range of operating parameters have been studied. The external plasma density and temperature were measured by Langmuir probes. A discussion is given of the confinement mechanism and of the energy balance, both in the external plasma and in the region of the cathode itself.

ISSN:0021-8979    

DOI:10.1063/1.1729002

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

Evaporated single‐crystal white tin films having an (001) orientation were examined by transmission electron diffraction. Sharp Kikuchi patterns were obtained and are discussed in terms of previous work. Their presence indicates a very high degree of crystal perfection in these ultra‐high vacuum evaporated films.

ISSN:0021-8979    

DOI:10.1063/1.1729003

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

The possibility that {112} planes in 3.25% silicon iron are active slip planes is investigated. This is found to be the case for certain axial orientations when the deformation temperature is above approximately 184°K. Below this temperature, the {110} plane is the observed operative slip plane. Utilizing a dislocation site etch‐pitting technique and a method of introducing dislocations into the material devised by Stein and Low, measurement is made of the velocity of edge‐type dislocations on {112} planes in 3.25% silicon iron single crystals. The velocity of these dislocations is found to be very sensitive to the applied stress in the range of velocities examined which is from 10−7to 10−2cm/sec. Three temperatures of testing are investigated: 198°, 233°, and 298°K. A method for the determination of the operative slip plane in 3.25% silicon iron as a function of the deformation temperature and the orientation of the deformed samples is proposed. This results in the observation that the stress to cause any given dislocation velocity increases more rapidly with lowering deformation temperature when slip occurs on {112} planes rather than on {110} planes.

ISSN:0021-8979    

DOI:10.1063/1.1729004

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

The solubility, diffusion, and electrical behavior of Li in GaAs have been investigated by means of chemical analysis, conductivity, and Hall‐effect measurements. Both floating‐zone and Bridgman crystals have been examined.The solubility of Li in GaAs from the equilibrium surface alloys has been determined from 500° to 1150°C. A maximum solubility of 4×1019Li cm−3occurs at about 1050°C. Solubilities from surface Li2O and gaseous LiBr have also been determined over limited temperature ranges.Li diffusion has been followed by electrical and chemical methods. The diffusion is nonideal and follows the relation,D*=0.53 exp(−1.0/kT), whereD* is the apparent diffusion coefficient. Li produces ``automatic'' compensation of GaAs. Out‐diffusion of Li results in acceptor formation. This behavior has been examined in detail and interpreted by postulating initial formation of stable (Li+Li=) doublets which, through the hole‐electron equilibrium, cause Li to dissolve as Li+donors to near compensation.A marked effect of donor doping on the solubility of Li has been found.Certain unexplained differences between crystals exist which are being further investigated.

ISSN:0021-8979    

DOI:10.1063/1.1729005

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

Single‐domain magnetization curves have been extended to the general ellipsoid. The calculation was carried out on an IBM 705 computer and was an iterative minimization of the energy as a function of the direction of magnetization for an arbitrary applied field. The results are similar to those of Stoner and Wohlfarth for ellipsoids of revolution. Tables containing reduced magnetization as a function of the magnitude and direction of the applied field and shape are available.

ISSN:0021-8979    

DOI:10.1063/1.1729006

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

Magnetic susceptibilities of Gd2O3and Dy2O3have been studied from about 300° to 1500°K and 300° to 1250°K, respectively. The paramagnetic susceptibility data of both oxides obey the Curie‐Weiss law. This information supports the suggestion that the small deviations from the Curie‐Weiss law found in gadolinium and dysprosium metals are due to conduction electron magnetization. The ions Gd3+and Dy3+in the oxides possess the Bohr magneton numbers 7.80 and 10.52, respectively.

ISSN:0021-8979    

DOI:10.1063/1.1729007

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

Coherent emission at 1.047 &mgr; from trivalent praseodymium in calcium tungstate was observed. This emission coincides with strong infrared fluorescence at the same wavelength and was found to be stimulated mostly by absorption of blue light by the3P0,3P1, and3P2bands. The emission corresponds to a1G4→3H4transition with the terminal level 377 cm−1from the ground state. The oscillation threshold was the same at 4.2°, 20°, and 78°K. No stimulated emission was observed at room temperature. The lifetime of the metastable state1G4is 50×10−3sec. A new technique used to measure the lifetime is described.

ISSN:0021-8979    

DOI:10.1063/1.1729008

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

A 6‐Gc traveling‐wave maser has been operated in a novel transverse field superconducting magnet. The magnet produces a uniform field in excess of 4000 Oe over a volume of 1.2×1.5×6 in. The field is directed across the shortest dimension (perpendicular to the direction of propagation) which permits nonreciprocal gain and attenuation. The TWM exhibited net gain in excess of 30 dB with 3‐dB bandwidths of about 20 Mc. Gain and bandwidth characteristics were the same as those measured on the same traveling‐wave maser in the field of a large laboratory magnet. This indicates a field homogeneity of about ±1 Oe or better in the superconducting magnet over the ruby volume of the maser since greater deviations would result in decreased gain and increased bandwidth.

ISSN:0021-8979    

DOI:10.1063/1.1729009

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

Critical regions at the level of significance &agr;=1, 5, 10, and 20% are presented in tabular and graphical form for testing whether or not a sample of single, cubic crystals is randomly oriented. The reasoning behind the statistical test is briefly discussed. The use of the tables is illustrated with a sample from the literature.

ISSN:0021-8979    

DOI:10.1063/1.1729010

出版商:AIP    

年代:1962

数据来源: AIP