摘要:

Coefficients for the prolate spheroidal solution of Laplace’s equation are derived in terms of a line of magnetization extending between the focal points of a spheroid. The present paper applies Havelock’s formula to obtain the magnetization corresponding to terms of a prolate spheroidal inverse model. Knowledge of the relationship of the prolate spheroidal coefficients to the equivalent magnetization distribution is required when mathematically modeling distinctly nonspherical static magnetic sources in the near field.

ISSN:0021-8979    

DOI:10.1063/1.328818

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Previous formulae for the calculation of the electrodynamic parameters of a ferromagnetic suspension arrangement are generalized to take differences in track and core materials and dimensions into account. The results of these calculations are compared to some more recent measured values.

ISSN:0021-8979    

DOI:10.1063/1.328819

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

In order to measure the thermal emission rate of a trap in semiconductor material without scanning the temperature, a new method, which utilizes a spectrum analyzer, has been developed. The theory on which our measuements depend is based on the relation between the time constant of a pure exponential wave and the relative amplitudes of its Fourier Components. The time constant is given by ts= (t/2r)[(10c−1)/(m2−10cn2)]1/2, wherec= (Xn−xm/10, t is the period of the exponential wave, andxnandxmare the amplitudes of thenth andmth harmonics in dB, respectively.

ISSN:0021-8979    

DOI:10.1063/1.328820

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Passive feedback stabilization of levitated coils is often considered in connection with the design of internal ring devices (Multipole or Surmac). A novel method using short‐circuited superconducting coils as stabilizers has been proposed. We present here a numerical calculation of the stability of one levitated coil in the field of two other levitating coils. The stability is provided by a set of superconducting short‐circuited loops placed around the floating ring. Stable configuration does exist. We also found that for a given magnetic configuration there exists a minimum current in the levitated coil below which it is unstable.

ISSN:0021-8979    

DOI:10.1063/1.328821

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

In recent years considerable interest has developed in the use of linear accelerators for various high‐current applications (radiation testing facilities, neutron spallation sources, heavy‐ion fusion, etc.). The beam dynamics and current limits in a linear accelerator are determined largely by the periodicity and phase‐space acceptance of the external focusing system and the particle oscillation frequencies (or phase shifts per focusing period), both without the space‐charge forces and with the space‐charge forces of the particle bunch. General formulas for the transverse and longitudinal current limits in terms of these fundamental quantities are derived. The relationships with the actual accelerator and particle beam parameters are examined for strong (quadrupole) and weak focusing field configurations. As a practical illustration, the results are applied to a drift‐tube linac with quadrupole focusing in the transverse direction and rf phase focusing in the longitudinal direction.

ISSN:0021-8979    

DOI:10.1063/1.328822

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

The molecular stopping cross sections of hydrogen sulfide, methyl sulfide, methyl disulfide, carbon disulfide, ethylene sulfide, proplene sulfide, trimethylene sulfide, thiophene, and sulfur hexafluoride have beem measured for 0.3–2.0 MeV He+ions. It is shown that the bond order correlation for the third period element sulfur is qualitatively in agreement with its second row counterpart, oxygen, but that the stopping cross‐section dependence on bond order is considerably less (?5% in sulfur compared to ?17% in oxygen). In the energy region where the stopping contribution of the valence electrons is largest, the atomic stopping cross sections of sulfur for double‐bonded, ring‐structured, and single‐bonded compounds decrease in the order eDB(S)≳eRING(S)≳eSB(S), a trend consistent with that observed for oxygen and carbon. The experimental results suggest a minimumd‐orbital involvement in SF6and reveal a lower peak energyEpeakand width d when S exists in the compound than when C, O, or F are present.

ISSN:0021-8979    

DOI:10.1063/1.328823

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

This paper reports results of measurements of radiation‐induced conductivity of Teflon (Teflon is a registered trademark of the E. J. du Pont de Nemours and Co.). FEP (polyfluorethylene propylene) foils irradiated by x rays at atmospheric pressure. The current induced by irradiation of the poled dielectric at exposure rates of the order of 102R/s, initially increases with time for 10–20 s, reaches a maximum, and subsequently decreases. After an irradiation time of about 1 h, a steady‐state value is attained which is of the order of 25% of the maximum current. Measurements are reported of the dependence of the current amplitudes on exposure rate, of the delayed component of induced conductivity, and of the behavior of samples which had been irradiated in short‐circuit before poling. Radiation‐induced polarization effects or space‐charge formation could not be detected. The behavior of the current‐time curves is interpreted in terms of a theory of unipolar (hole) conduction.

ISSN:0021-8979    

DOI:10.1063/1.328824

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

The magnetic suspension system consisting of a metallic cylindrical shell encircling an alternating‐current filament is analyzed by vector field methods for arbitrary relative orientations of shell and current axes. The induced magnetic field and resulting force‐torque system, and associated eddy‐currents, are calculated for a variety of shell constructions: homogeneous shells, shells with annular hollow space, and shells composed of annular layers of different metals. End effects neglected in the computations are analyzed in a companion paper. The biaxial shell‐filament systems treated model the magnetic suspension in ’’disturbance compensation systems’’ for Navy navigational satellites.

ISSN:0021-8979    

DOI:10.1063/1.328825

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Whereas conventional foilless electrostatic lenses without axial electrodes or space charge show positive sphericalCsand chromaticCcaberration for paraxial rays, results presented here show that for periodic or quasiperiodic electrostatic fields, low or negative values ofCcandCscan occur if the rays pass through zonal regions. Not only can cone‐edge focusing occur, but cone focusing can be found at several values of the emission angle. As a possible application, charged particles of sufficiently high velocity originating from a weak point source, for instance, Auger or internal conversion electrons, can be focused onto a small spot by utilizing an annular rather than a circular aperture.

ISSN:0021-8979    

DOI:10.1063/1.328826

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

An experimental test has been performed of a novel ion diode intended for inertial confinement fusion applications. The diode is a small thin‐walled evacuated glass sphere (nicknamed a ’’light bulb’’) which is irradiated by relativistic electron beams transported to the sphere via plasma channels. The virtual cathode formed by the electrons in the light bulb accelerates ions radially inwards from the walls of the sphere. The ions are focused on a levitated central target. Qualitative aspects of one‐dimensional theoretical analyses of the light bulb are supported by the experimental results reported here. However, the overall ion beam generation efficiency in the experiment is evidently substantially below that of the simple theory, probably owing to two‐dimensional effects.

ISSN:0021-8979    

DOI:10.1063/1.328827

出版商:AIP    

年代:1981

数据来源: AIP