摘要:

A dimensionless solution is given for continuous current flow in a solid dielectric, which undergoes electron‐induced collision ionization. A method is developed for finding the current‐voltage characteristic of the dielectric from this solution, given the emission function of the cathode and a blocking anode. The results are used to infer the thickness dependence of dielectric breakdown strength based on the model considered.

ISSN:0021-8979    

DOI:10.1063/1.1657111

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

Alternating current bridge, step response, and dc conduction measurements are reported on anodic oxide films on tantalum with counterelectrodes of gold and indium. The step response currents followed at−nlaw, wherenwas from 0.9 to 1.0 depending on conditions. For a linear dielectric response, this corresponds to &egr;″ (&ohgr;) varying as &ohgr;n−1, i.e., as either &ohgr;−0.1or independent of frequency, respectively. For low values of applied step voltages with specimens made in certain ways, the magnitude of the step response agreed with extrapolated bridge measurements. Deviations are discussed in terms of electronic space‐charge effects. Below room temperature, &egr;″/Twas constant as expected for a superposition of Debye losses with relaxation times determined by a thermal activation process with a flat distribution of activation energies. The slope of logJvsF1/2plots for electronic conduction corresponded to the Schottky or Poole‐Frenkel values depending on whether the Ta electrode was negative or positive.

ISSN:0021-8979    

DOI:10.1063/1.1657112

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

Solutions of the wave equation are obtained for TE0mnand TMlm0modes in cylindrical cavities containing a coaxial, annular plasma column. The radial electron density distribution is assumed to be of the formne=n0[1−&ggr;1(r/a)2−&ggr;2(a/r)2], wheren0, &ggr;1, and &ggr;2are constants andais the outer radius of the plasma. The results can be used to determine the effects of density gradients on measurements of electron densities and collision frequencies by the cavity method. Some illustrative examples are presented.

ISSN:0021-8979    

DOI:10.1063/1.1657113

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

An efficient, exact solution for the complete field structure inside, in, and outside a spherical shell of arbitrary linear media, excited by a monochromatic plane wave is given. The fields in each region are expressed as vector multipole expansions whose coefficients are evaluated through the boundary conditions. The numerical reduction involves the use of modified spherical Bessel functions and recursion relations. The technique is illustrated by numerical results for the fields inside an imperfectly conducting shell. This analysis virtually exhausts the class of problems of spherical shells constructed of linear media.

ISSN:0021-8979    

DOI:10.1063/1.1657114

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

The extraordinary wave transmission through the afterglow of an rf‐excited, electrodeless, helium discharge has been investigated experimentally. The discharge approximates a low collision frequency plasma slab of relatively uniform electron density in a uniform magnetic field. Measurements were performed at 18.0 and 9.15 GHz. A transmission minimum occurs very close to the higher frequency cutoff and a large decrease in transmission occurs close to the lower frequency cutoff. The plasma cutoff positions are approximately independent of energy in the electron energy range from thermal energy to a few electron volts and of pressure in the pressure range from 0.08 to 2.5 Torr. The position of the transmission minimum coincides with the position of the emission peak previously observed.

ISSN:0021-8979    

DOI:10.1063/1.1657115

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

Polycrystalline tungsten ribbons tend to recrystallize on extended outgassing to a preferred orientation near the⟨1¯10⟩zonal axis between the⟨001⟩to⟨112⟩directions, the most probable orientations being in the⟨115⟩to⟨113⟩directions. Work function measurements on nine different crystal planes between the⟨001⟩to⟨112⟩directions have been made and show variations from 4.34 to 4.72 eV. The area average value from 15 different ribbons is 4.46 eV but the variation between ribbons can be as high as 0.2 eV.

ISSN:0021-8979    

DOI:10.1063/1.1657116

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

Exact relativistic solutions for the one‐dimensional space‐charge‐limited diode, and for the one‐dimensional diode with finite field at the cathode plane are given. The results are compared with approximate solutions which are useful in different energy ranges.

ISSN:0021-8979    

DOI:10.1063/1.1657117

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

Soda‐lime glass surfaces, heated between 600° and 900°C in vacuum, have been shown to emit sodium and potassium ions and electrons. The experimental emission rates are:INa+=4.75×1037 exp(−5.61 eV/kT) ions/cm2/sec,IK+=3.30×1032 exp(−4.37 eV/kT) ions/cm2/sec,andIe=0.288T2 exp(−3.58 eV/kT) A/cm2.

ISSN:0021-8979    

DOI:10.1063/1.1657118

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

Platinum evaporated on a clean iridium surface at temperatures as low as 200°K produces epitaxial layers, as shown by field ion microscopy. If the iridium surface has been exposed to the atmosphere after forming, the temperature required for epitaxy rises to about 375°K (100°C). Even this temperature is well below that required for high mobility of the incoming atoms over the surface, as assumed in present theories of the formation of epitaxial layers.

ISSN:0021-8979    

DOI:10.1063/1.1657119

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

The statistical distribution of the number of emitted secondary electrons per primary incident on transmission alkali‐halide dynodes has been studied. For high primary energies (1 MeV), a model based on the theory of dielectric energy loss and the secondary electron‐phonon interaction is proposed to account for statistical distributions. Measurements of distributions from 500‐Å‐thick films of CsI, KCl, and LiF have been carried out both at high energies and for primary energies near 9 keV corresponding to the maximum of secondary yield. It is shown that with some simplifying approximations, the model proposed can be used to calculate the distributions observed with high‐energy primaries. Qualitatively, it is also possible to use the ideas proposed to understand the experimental results at low energy. Although in the literature the statement is often made that secondary emission distributions can be expected to be Poissonian, it is shown in this paper that there is very little firm basis for such a statement, and it is only through a knowledge of the detailed phenomena controlling secondary emission that a particular distribution can be predicted.

ISSN:0021-8979    

DOI:10.1063/1.1657120

出版商:AIP    

年代:1969

数据来源: AIP