摘要:

The resistivity of a nonferromagnetic conductor can be deduced from the change in mutual inductance between two coils when the sample is inserted. A method is described for measuring mutual inductance over a range of frequencies and this can be used to detect change in resistivities of the order of ± 10−13&OHgr; cm.

ISSN:0021-8979    

DOI:10.1063/1.1662790

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

The effects of variations in carrier mobility and its field dependence on the xerographic discharge characteristics of a photoreceptor have been explored theoretically. Particular emphasis has been placed on the dependence of optimum exposure to reach optimum contrast potential and the latter values on mobility. The discharge characteristics are divided into three categories: (i) flash exposure where the exposure time is much shorter than the carrier transit time, (ii) emission‐limited discharge which is realized by higher mobility photoreceptors, and (iii) space‐charged‐perturbed or space‐charge‐limited discharge which is seen in low‐mobility photoreceptors. It is shown that in the latter case the optimum contrast potential is dependent on the time of observation (synonomous with development time).

ISSN:0021-8979    

DOI:10.1063/1.1662791

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

Doubly charged ions were observed during the decay period of plasmas produced in neon as well as in argon at reduced gas pressures ranging from 0.14 to 1 Torr. The measured time dependence of both the Ne2+ion density and the Ar2+ion density were corrected for the effect of diffusion cooling of the electrons. The reaction rate constant for the partial charge exchange reaction Ne2++Ne→Ne++Ne+was found to bek=(9 ± 2) × 10−14cm3sec−1. For the reaction rate of the similar reaction in argon, only an upper limit could be obtained. The value of the mobility of Ne2+in neon was found to be &mgr;(Ne2+)=6 ± 1 cm2/V sec. The value of the mobility of Ar2+in argon was consistent with previously published data.

ISSN:0021-8979    

DOI:10.1063/1.1662792

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

Exact closed‐form expressions for the Fresnel region electric and magnetic fields of circular loop and annular slot antennas are given in terms of the functionsen(&sgr;,&ggr;)=(1/2&pgr;)02&pgr; cos(n&PHgr;) sin[&sgr;(1–2&ggr; cos&PHgr;)1/2] d&PHgr;andfn(&sgr;,&ggr;)=(1/2&pgr;)02&pgr; cos(n&PHgr;) cos[&sgr;(1–2&ggr; cos&PHgr;)1/2] d&PHgr;,where ‐ ∞ < &sgr; < ∞ and 0 ≤ &ggr; ≤ 1/2. For a circular loope antenna with a constant current distribution the Fresnel region fields are obtained in terms of the functionsqn(&sgr;,&ggr;)=fn(&sgr;,&ggr;)+ien(&sgr;,&ggr;), withn=0,1, and 2, and for a cosine current distribution the Fresnel region fields are obtained in terms of the functionsqn(&sgr;,&ggr;), withn=0,1,2,3, and 4. The magnetic field of an annular slot antenna excited by a constant voltage is expressed exactly in terms of an infinite series involving the functionsqn(&sgr;,&ggr;). The Fresnel region magnetic field of the annular slot antenna is simply given in terms ofq1(&sgr;,&ggr;). The functionsqn(&sgr;,&ggr;) permitted a simple evaluation of the electric and magnetic field strength in the Fresnel region. The functionsqn(&sgr;,&ggr;) forn=0,1,2,3, and 4 are tabulated for values of &sgr;=0.5, 1, 2, 5, 10, 25, and 50 and values of &ggr; from 0.01 to 0.5.

ISSN:0021-8979    

DOI:10.1063/1.1662793

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

A study is made of the stability of quasineutral low‐frequency (&ohgr; ≪ &ohgr;ci) flute waves in a low‐&bgr; collisionless plasma column immersed in a uniform axial magnetic field. The column has a Gaussian number density profile and a dc radial electric field. The differential equation which describes the waves is solved both analytically and numerically for the eigenfrequencies and eigenfunctions. For the case of uniform rotation of the column, analytical solutions are obtained to determine the properties of a column bounded by a conducting cylinder. The instability is a centrifugal flute wave for this case. The boundary can be stabilizing or destabilizing for them= 1 azimuthal mode, depending on its location, while for all other modes, the boundary is stabilizing. For a nonuniformly rotating column, the effects of gradual shear and abrupt shear are considered using numerical solutions. By following the evolution of these modes as the profiles are changed continuously, a unified picture of their behavior is developed. Again the behavior of them= 1 mode is found to be different from that of the higher‐order modes, as illustrated by them= 2 mode. Them= 1 mode is quite sensitive to the rotation of the column near the boundary, while them= 2 mode depends more on an average over the column. Also, for abrupt shear, them=2 mode evolves into a Kelvin‐Helmholtz instability, while them= 1 mode does not.

ISSN:0021-8979    

DOI:10.1063/1.1662794

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

Calculations assuming thermal equilibrium have been made of properties of cylindrical arc plasmas which decay after the removal of the electric field. Account is taken of energy losses due to thermal conduction and radiation, self‐absorption effects being included where possible in the treatment of radiation. The maximum possible influence of radial convection is calculated by assuming that convective flow maintains a uniform pressure in space and time. Comparisons are made of the calculated decay of electrical conductance with experimental measurements, where available, for A, N2, SF6, H2, and air; curves are given showing the contributions of thermal conduction, convection, and radiation to the decay. The theoretical results underestimate the rapid decays of electrical conductance that have been observed for plasma temperatures of less than 10 000 °K in air, and less than 7000 °K in SF6, but good agreement between theory and experiment is obtained for argon. Information from rate coefficients supports the view that the rate of atomic recombination to form molecules is insufficient to maintain thermal equilibrium and as a result there is an enhanced rate of cooling. Theoretical transient temperature profiles in air are also compared with published experimental profiles.

ISSN:0021-8979    

DOI:10.1063/1.1662795

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

Numerical results are presented for the characteristics of heavy‐ion laser‐produced plasmas. A conversion ratio defined as x‐ray power/absorbed power is then computed. Collisional‐radiative equilibrium is assumed for the ionization model. In the case of low radiation emission, a relation between laser flux and plasma temperature is derived. The one‐dimensional geometrical model is then corrected in the expansion by assuming that the emission occurs, in fact, over a lengthLonly. Results are given and compared with experimental ones. The influence of the laser wavelength is also discussed and conclusions on the possible applications of these laser‐produced plasmas are drawn.

ISSN:0021-8979    

DOI:10.1063/1.1662796

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

The electron‐ion recombination rate has been measured in a high‐pressure CO discharge at room temperature and at pressures from 100 to 700 Torr. The effective two‐body rate coefficient was found to be in the range 10−7−10−6cm3/sec, with an electron temperature dependence ofTe−1.6associated with the average electron energy from 0.2 to 0.7 eV. The results indicate a small pressure dependence, of less than a factor of 2, over the experimental pressure range. The principal ion at these pressures was probably the dimer,C2O2+, or a high‐order polymer ion based on ion‐molecule reactions in CO reported in the literature.

ISSN:0021-8979    

DOI:10.1063/1.1662797

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

The characteristics of electromagnetic surface waves supported by a plane interface separating a semi‐infinite region of free space from another semi‐infinite region consisting of a plasma streaming parallel to the interface are investigated for the case in which the wave is progressing either in or opposite to the direction of the stream. The behavior of the surface wave is drastically different from the case in which the plasma is stationary. The surface wave has backward‐wave regions. For a certain range of frequencies below the plasma frequency, the surface wave undergoes traveling wave amplification in the direction of the stream. When its wave number is in a certain range, the surface wave progressing in a direction opposite to that of the stream is convectively unstable. The characteristics of this surface wave instability are analyzed.

ISSN:0021-8979    

DOI:10.1063/1.1662798

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

The effect upon measurements of electron temperature in high‐pressure plasmas of the cooling of the plasma electrons by the inherently cold layer of gas surrounding the probe has been investigated. Theoretical considerations indicate that while cooling effects can be substantial, accurate electron temperature measurements can be obtained if the probe is sufficiently small or is moved through the plasma at sufficient velocity. These conclusions are at variance with the calculations of some other workers but are in good agreement with experimental results reported in this paper.

ISSN:0021-8979    

DOI:10.1063/1.1662799

出版商:AIP    

年代:1973

数据来源: AIP