摘要:

In order to gain some insight in the problem of space charge neutralization of ion beams we make use of a previous calculation to discuss the unidimensional flow of positive ions in a tube where both ions and electrons issue from an emitter surface but only ion current is collected by means of an accelerating electrode. The resulting ion flow can be neutralized to varying degrees by the electrons present. We find that even in the absence of collisional interactions the potential distribution in the tube may closely resemble the electrode sheath and positive column structure familiar to glow discharges. This is the situation to be expected whenever the ion current has values far in excess of that predicted from a zero degree of neutralization space charge limited theory.

ISSN:0021-8979    

DOI:10.1063/1.1735735

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

An ultrasonic cw resonance technique for the measurement of the velocity of sound in solids is described. The end correction due to the presence of the transducer and coupling film can be calculated from consideration of a transmission‐line equivalent circuit. An experimental comparison is made of the cw and two pulse techniques over the frequency range 5 to 45 Mc. Application of the cw resonance technique is made to the measurement of the room‐temperature adiabatic elastic constants of single crystals of RbBr, RbI, CsBr, and CsI. A tabulation of the important elastic properties of these crystals is presented.

ISSN:0021-8979    

DOI:10.1063/1.1735736

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

An investigation has been made of the cleanup of inert gases by a gas discharge. The cleanup of rare gases in a tube in which metal is being sputtered is governed largely by two factors. First, the rate at which the metal is sputtered, and second, the potential of the surface on which the metal lands. At small negative or positive potentials on the surface collecting sputtered metal there is a slow cleanup rate caused by uncharged species being buried by sputtered metal. At more negative potentials burial of ions becomes important, and cleanup is much more rapid. Recovery has been effected by heating to the evaporation temperatures of the metal. As the metal evaporates the buried gas is liberated. Hundreds of equivalent monolayers of argon have been cleaned up with only a total recovery of about one equivalent monolayer by heating at 1500°C. This shows that even with a forced ``solubility'' of the order of one per cent we find no evidence for significant diffusion of argon in metals. An electrode collecting ions at a uniform current density over the surface will have a net cleanup rate of zero on that surface after the initial cleanup of a small amount of gas. After the initial disappearance of some gas, resputtering will occur liberating the cleaned up gas as fast as it is being cleaned up.

ISSN:0021-8979    

DOI:10.1063/1.1735737

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

Detailed measurements of the fast‐neutron and gamma‐ray bombardment behavior of germanium‐alloy‐transistor current‐gain have been obtained concurrent with exposure. These data indicate that previously reported analyses, which lead to a linear dependence of common‐base current‐gain on fast neutron exposure, yield a good approximation for thenpndevice, but are not of general validity for thepnpgermanium transistor. The extent of departure from the linear approximation depends on the width and conductivity of the base‐region and can be appreciable in many cases of practical interest.For thepnpgermanium transistor it is necessary to take additional account of both changes during bombardment of the minority‐carrier recombination rate at bombardment introduced and initially present recombination centers and changes in the width of the collector junction depletion layer. Observed bombardment curves are in good agreement with an analysis which includes these effects. From initial slopes of the current‐gain bombardment curves, values of the product of fast‐neutron‐exposure times minority‐carrier‐lifetime at bombardment introduced recombination centers are 9.7×107for 2.7 ohm‐cmp‐type and 14.2×107, 6.0×107, and 1.3×107, for 3.6 ohm‐cm, 1.2 ohm‐cm, and 0.2 ohm‐cmn‐type germanium, respectively, in units of sec‐neutrons/cm2.

ISSN:0021-8979    

DOI:10.1063/1.1735738

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

The question of the existence of an intrinsic bias in colemaniteabovethe Curie point is studied and compared with experimental results. It is concluded that a bias does exist above the Curie point and that it is completely responsible for the pyroeffect experimentally observed there. Some formulas are derived, connecting the pyroeffect and the intrinsic bias, and are compared with data available in the literature.

ISSN:0021-8979    

DOI:10.1063/1.1735739

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

The current from a beta particle source measured through a thin dielectric cannot be predicted simply from the absorption curve. A model is considered in which the space charge formation in the medium results in a component of current in addition to that of the betas transmitted. Calculations developed from this model give a close approximation to experimental results.

ISSN:0021-8979    

DOI:10.1063/1.1735740

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

Single crystals of a number of binary iron‐base alloys were grown, fabricated, and tested for magnetic anisotropy (K1) and magnetostriction (&lgr;100and &lgr;111). The additions made to iron included vanadium, molybdenum, germanium, chromium, titanium, and tin. The anisotropy of iron was lowered by the addition elements with the possible exception of tin. On the other hand, &lgr;100of iron was generally raised by these addition elements. Only titanium and tin lowered &lgr;100; however, titanium had limited solublilty in iron and tin caused embrittlement.

ISSN:0021-8979    

DOI:10.1063/1.1735741

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

A geometrical theory is developed for the analysis of surface wave excitation and propagation. The surfaces along which the surface waves propagate may be either curved or flat, and may have either constant or variable properties. The theory is based on the concept of a complex or imaginary ray. The excitation coefficient which enters the theory is determined from the solution of a canonical problem—that of a line source over an impedance plane. Then the theory is applied to the surface wave excited by a line source, on a wedge with variable surface impedance. The result agrees precisely with the asymptotic form of the exact solution. Another application is made to the surface wave excited on a cylinder by a line source. The result also agrees with the exact solution.

ISSN:0021-8979    

DOI:10.1063/1.1735742

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

The slowing down of a primary displaced atom of high energy in a solid is investigated in detail. Physically interesting quantities, such as the total distance travelled and the vector distance to the end of the path, are discussed in terms of certain averages for hard core potentials with general dependence of the core radius on energy. These averages are explicitly calculated for a screened Coulomb potential for the purpose of comparison with experimental ranges observed in different metals. Theoretical values for the range can be derived. Comparison with the experimental data gives a value for the screening radius of the interaction potential which is about twice the value originally suggested by N. Bohr.

ISSN:0021-8979    

DOI:10.1063/1.1735743

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

The threshold for displacement of the sulfur atom from a lattice point in CdS has been measured to be 8.7 ev. This is accomplished with 115‐kev electrons. This is also the threshold for the production of green edge emission centers and of centers for a red fluorescence band with a maximum intensity at about 7200 A. In crystals which show edge emission before bombardment, the edge emission is removed by electron bombardment in the energy range 2.5 to 200 kev. The red luminescence is not removed by electron bombardment but increases in intensity with bombardment above the threshold. The radiation ``annealing'' of the edge emission is accomplished even in crystals which do not thermally anneal. A model is proposed with the sulfur interstitial atom the center for edge emission, and the sulfur vacancy the center for the red emission band.

ISSN:0021-8979    

DOI:10.1063/1.1735745

出版商:AIP    

年代:1960

数据来源: AIP