摘要:

An optical superheterodyne analyzer, which is destined for high resolution spectral analysis in the optical domain, is described. The optical local oscillator of continuously variable frequency, the core of this analyzer, is obtained by means of an acousto‐optic effect. By changing the acoustic frequency linearly, and by appropriately choosing the order of diffraction, one can scan the frequency of the local oscillator beam over a range of 2.4 GHz. This optical superheterodyne system is analogous to the one used in rf receivers. By this proposed method of optical spectral analysis, we have overcome three drawbacks existing in the classical heterodyne detection. Firstly, the analyzable domain extends to 2.4 GHz instead of 400 MHz for heterodyne detection; secondly, we use a fixed frequency tuned amplifier instead of an expensive rf spectrum analyzer. Finally, there exist no

ISSN:0034-6748    

DOI:10.1063/1.1134338

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

An apparatus has been developed for the measurement of the permeance (effective permeability–thickness product) of magnetic films for frequencies 1–100 MHz and permeances up to 20 000 &mgr; with an accuracy of ±100 &mgr;. This is suitable for permalloy films in the 0.5–5 &mgr; thickness range, which are used in thin film recording heads operating in this frequency range.

ISSN:0034-6748    

DOI:10.1063/1.1134339

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

In order to ionize molecular deuterium a photon energy greater than 15.6 eV is required. This is created by radiation from bombardment of a thick wall by energetic electrons, as in x‐ tubes. A high voltage pulse extracts the electrons by field emission from the sharp pointed electrode and accelerates them to the cylindrical anode. The degree of ionization is measured with an ionization cell and has been measured at pressures from 5×10−6up to 5×−4Torr in D at a distance of 70 cm from the source, averaged over the volume of the chamber. This made it possible to start discharges in the T.F.R. (Tonomav de Fontenaya‐Tokomak from as low as 10−5, giving an appreciable increase in the range of working pressures of the T.F.R. experiment.

ISSN:0034-6748    

DOI:10.1063/1.1134340

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

A parallel‐plate Stark cell giving a very homogeneous electric field is described. It can be used either for Stark spectroscopy in the infrared and microwave ranges or in infrared–microwave double resonance experiments. Microwave absorption lines, 12.600 GHz frequency shifted, have been observed; it is more than 36 times as much as earlier displacements obtained with such cells. For pressures up to 30 mTorr, a suitable device keeps the breakdown voltage always above 10 kV, corresponding to an electric field of 50 kV/cm.

ISSN:0034-6748    

DOI:10.1063/1.1134341

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

A focused, Q‐spoiled laser, aligned along the interelectrode axis of a pulse charged switch assembly, was used to initiate the conduction of an overvolted transformer oil filled gap. Laser power varied between 5 and 200 MW and the voltage pulse exhibited a risetime of 500 nsec to a voltage of 700 kV. A parametric study of the factors affecting the delay between the laser pulse arrival at the gap and conduction of the gap was accomplished, in which the effects of the focal point location, laser power, switch polarity, and voltage on the gap at laser arrival were determined. Delay times as short as 12 nsec were recorded with jitter, a measure of reproducibility, in the low nanosecond region.

ISSN:0034-6748    

DOI:10.1063/1.1134342

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

Several solid source loading materials for the production of a boron ion beam with a hot filament hollow cathode ion source are compared. As far as easy handling and large B+currents are concerned, oxidized boron nitride is shown to be an excellent choice. Currents of 80 &mgr;A11B+are routinely obtained at the target from an oxidized BN source.

ISSN:0034-6748    

DOI:10.1063/1.1134355

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

The construction of a rotatable transducer for generating and detecting pulses of plane‐polarized 10 MHz ultrasound is described. The usefulness of the transducer is demonstrated in attenuation measurements made along various symmetry directions on a single crystal, and in acoustical birefringence measurements made on anisotropic solids, as well as elastically deformed structural alloys. The calibration of the polarization of the transducer, and its utilization to determine the directions of principal axes of the shear waves, are also reported.

ISSN:0034-6748    

DOI:10.1063/1.1134356

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

A simple instrument to make absolute velocity calibrations of velocity transducers used in Mo¨ssbauer effect measurements is described. A short comparison with other calibration techniques is made.

ISSN:0034-6748    

DOI:10.1063/1.1134357

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

A low noise and low drift amplifier has been constructed using several monolithic operational amplifiers in parallel. It is shown that each amplifier may be connected by only three resistors. An input noise of 0.15 &mgr;V (p–p) in the band 0.1–10 Hz was obtained with six amplifiers, and the noise is expected to decrease asN−1/2as the number of units is increased.

ISSN:0034-6748    

DOI:10.1063/1.1134319

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

A modified dry dust disperser has been used to produce test aerosols from very fine powders which show a tendency to agglomerate in feeders and dispersion equipment.

ISSN:0034-6748    

DOI:10.1063/1.1134320

出版商:AIP    

年代:1975

数据来源: AIP