摘要:

An automated ferroelectric hysteresis loop tracer, developed using an INTEL 8085 microprocessor is described. This setup can be used to study the growth of a hysteresis curve at any desired temperature instantaneously after the application of a field. Since the setup allows the storage of data for each cycle of the applied field, this can be used to study the response of ferroelectric domains in an applied alternating field with time on unpoled or poled samples. The setup is interfaced with a personal computer to obtain directly the values of loop parameters.

ISSN:0034-6748    

DOI:10.1063/1.1144596

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

The beam‐bending method is very useful for the viscosity determination of glasses, but the time spent to run the measurement is usually very long. The present note describes the performance of an improved beam‐bending viscosimeter at the support stand and loading rod to get the faster measurements of high viscosity glasses with better reliability and precision. The testing time was reduced from 8 to less than 4 hours to run one measurement at three different temperatures (1100, 1200, and 1300 °C), with the precision of almost one order of magnitude better (±0.01 for 1g &eegr; in poise).

ISSN:0034-6748    

DOI:10.1063/1.1144597

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

Two simple three‐electrode spark gaps have been constructed to operate at high voltages up to 30 kV for use in a gas laser triggering system. The performance of each spark gap has been tested in a nitrogen laser system designed for this purpose, and the results are described in this report. The pressure‐controlled spark gap has shown better results in terms of stability and lifetime, and it is highly reliable for high repetition rate switching.

ISSN:0034-6748    

DOI:10.1063/1.1144598

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

An analog instrumentation for estimating dimensions of chaotic dynamical systems has been developed. The technique employs time series of the Poincare´ points successively displayed on the screen of an oscilloscope. It provides a rapid way to estimate the pointwise dimension from a single variable directly in an experiment. The instrumentation is easy to build and is convenient to employ. We have tested it by applying to periodic and quasiperiodic oscillators, and have verified by means of the fractal two‐dimensional Poincare´ map, simulated from the Duffing–Holmes differential equation. The measured values well agree with the computer calculated ones.  

ISSN:0034-6748    

DOI:10.1063/1.1144599

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

In time resolved measurements of neutron emission, the most common practice is to use a plastic scintillator coupled to a fast photomultiplier. There are different ways of coupling the light emitted by the scintillator to the photomultiplier (PM), according to the size and the shape of the scintillator. Some of the more usual coupling geometries are light pipes, Plexiglas cones with silvered walls or mirror ‘‘huts’’ facing the PM window.

ISSN:0034-6748    

DOI:10.1063/1.1144600

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

A simple technique is demonstrated for preventing microchannel plate (MCP) response to scattered laser light in a multiphoton ionization experiment. The MCP is gated on after the laser pulse, with a turn‐on time of less than 1 &mgr;s, by switching its cathode from 0 to −1900 V. The high‐voltage pulse circuit uses power MOSFETs and was designed according to the procedure of Baker and Johnson [Electron. Lett.29, 56 (1993)].  

ISSN:0034-6748    

DOI:10.1063/1.1144601

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

This paper describes a simple portable mechanical structure to support a medium size cryostat. The structure can provide adequate support for an helium‐3 cryostat with an 8 T magnet while the Dewar can be stored between experiment in a pit hole area below the temporary structure.

ISSN:0034-6748    

DOI:10.1063/1.1144602

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

An improved model of the plasma column erosion is proposed for the understanding of the resistivity dependence of the plasma delay in a silicon surface barrier detector (SSBD). The resistivity of a SSBD has influence in the electric field strength in a depletion layer with the presence of a dielectric plasma column. The plasma delay for two SSBD’s with different resistivities was measured with 61 MeV16O ions, and the results are clearly reproduced by this model.  

ISSN:0034-6748    

DOI:10.1063/1.1144603

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

We report a bakeable vacuum seal between glass blanks and a stainless‐steel conflat vacuum port without leaks at the 10−10 atm cm3 s−1level. The seal permits true optical windows, both flat and coated, to be economically used in ultrahigh‐vacuum applications

ISSN:0034-6748    

DOI:10.1063/1.1144604

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

The frequency dependence of the complex ac susceptibility of a magnetic conducting sphere is derived. The resultant formulas can be used to determine electrical conductivity from ac susceptibility measurements, to calculate ac susceptibilities of standard samples for the calibration of ac susceptometers, and to analyze ac losses in materials research.

ISSN:0034-6748    

DOI:10.1063/1.1144605

出版商:AIP    

年代:1994

数据来源: AIP