摘要:

In the present letter, highTcbulk superconductor wigglers were proposed as one of the novel applications of highTcsuperconductor lenses (Supertrons). Their operation was also shown experimentally. The bismuth‐based bulk superconductor wiggler had sinusoidal surfaces with a period length of 35 mm and an amplitude of 2 mm. The wiggler deflected intense electron beams of 340 keV, 1 kA, and 10 ns of duration time with an amplitude of about 1.5 mm.

ISSN:0003-6951    

DOI:10.1063/1.106000

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

An optical time‐domain reflectometer (OTDR) with −136 dB minimum detectable reflectivity and 14 &mgr;m spatial resolution is developed based on low coherence interference. The high sensitivity was accomplished by using a high‐power superluminescent diode module with a 1.5 mW fiber output and a new system configuration, both for effectively operating the balanced heterodyne detection. The reflectivity of −136 dB is only 6 dB above the shot noise limit. The first observation of 1.3 &mgr;m wavelength Rayleigh backscattering in single‐mode fibers was successfully made by the OTDR with a 17 dB dynamic range and 14 &mgr;m spatial resolution.

ISSN:0003-6951    

DOI:10.1063/1.106408

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Electro‐optic sampling is performed on a high‐speed silicon multiplexer integrated circuit using a gain‐switched semiconductor laser and an external probe tip fabricated from GaAs. An approximate electrostatic model is used to calculate the dependence of the electro‐optic modulation on the height of the probe tip above the circuit, the geometry of the circuit, and the dielectric constants of the probe tip material and the passivation layer (if any) on the circuit. The measured variation of the electro‐optic modulation with probe tip height is in good agreement with the prediction of the model.

ISSN:0003-6951    

DOI:10.1063/1.106001

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

High‐power and high‐reliable operation of transverse‐mode stabilized InGaAlP laser diodes has been achieved by a selectively buried ridge waveguide structure with a thin (0.02 &mgr;m) active layer. A composition‐shifted In0.5+&dgr;Ga0.5−&dgr;P active layer was employed in order to improve the temperature characteristic. A maximum cw light output power of 54 mW was obtained for the laser with antireflection and high‐reflection coatings. A high‐power cw operation above 30 mW output power was maintained even at a 60 °C heat‐sink temperature. Stable cw operation exceeding 1000 h has been achieved for 20 mW output power at 50 °C.

ISSN:0003-6951    

DOI:10.1063/1.106002

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Molecular beam epitaxy of Nd3+‐doped CaF2monocrystalline layers on CaF2substrates is demonstrated. Nd concentration is controlled by the temperature of an evaporation cell containing NdF3. Photoluminescence spectra of the samples show emissions from Nd3+centers in tetragonal symmetry sites as a consequence of the charge compensation mechanism provided by interstitial F−ions.

ISSN:0003-6951    

DOI:10.1063/1.106003

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

A new 2×2 propagation matrix for obliquely propagating light is used to compute the electro‐optics of an electrically controlled birefringence liquid‐crystal display, with arbitrary viewing angle. The results are the same as those obtained by the generalized geometrical optics approximation and are in good agreement with those computed by the 4×4 propagation matrix. By approximating the liquid‐crystal medium as a homogeneous medium with a field‐dependent orientation, a simple analytic expression is obtained for describing the optical transmission. The computed electro‐optical transmissions at oblique angle show a good agreement between the simple formula and the full computation having the liquid crystal divided into 500 sublayers.

ISSN:0003-6951    

DOI:10.1063/1.106004

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We have observed a substantial decrease in barium sputter yield as a function of exposure time when a barium surface is bombarded with an intense flux of positive hydrogen or deuterium ions, extracted from a plasma. This effect is attributed to an increase of surface hydrogen concentration which results in enhanced preferential sputtering of hydrogen surface atoms. The sputtering process is observed by means of optical emission spectroscopy. Whenever the surface is saturated with hydrogen, the sputtered barium yield is constant in time, and scales with the sputter coefficient, which is dependent on the energy of the incident ions. The relative decrease of the sputtered barium yield is shown to scale with the incident positive ion current density as the saturation concentration depends on this current density.

ISSN:0003-6951    

DOI:10.1063/1.106005

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The negative and positive ion mass spectra from radio frequency glow discharges in boron trichloride and 90% argon‐10% boron trichloride mixtures have been investigated by amplitude modulation of the discharge excitation. The negative ion spectrum from pure boron trichloride was found to extend beyond 200 amu under most conditions even though positive ions above 120 amu were not detected under any conditions. Surprisingly, only trace signals of BCl−3were found from the discharges, while the signals from Cl−, BCl−4, B2Cl−4, and B2Cl−5were much larger. We were unable to detect either positive or negative ions above 120 amu from 10% boron trichloride discharges.

ISSN:0003-6951    

DOI:10.1063/1.106006

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We report on new observations of positron stopping in a series of Al foils mounted on glass backplates for incident energiesEin the range 10–50 keV. The measured median penetration depths forE≳30 keV are found to differ significantly from values derived from the empirical power law model of A. P. Mills, Jr. and R. J. Wilson [Phys. Rev. A26, 490 (1982)]. The associated disparity between the measured implantation profiles and their analytic representations, and the consequent implications for defect profiling analysis, are discussed.

ISSN:0003-6951    

DOI:10.1063/1.106007

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The angular dispersion of surface acoustic wave velocities on {100} planes of a nickel single crystal has been measured using continuous wave scanning acoustic microscope and Brillouin scattering. This dispersion is used to calculate the elastic constants. They are compared with bulk ultrasonic measurements performed on the same sample. Systematic differences have been observed in elastic constants and anisotropy. These are attributed to surface damage due to mechanical polishing of the specimen.

ISSN:0003-6951    

DOI:10.1063/1.106008

出版商:AIP    

年代:1991

数据来源: AIP