摘要:

Simple alignment fixtures to aid in maintaining the alignment of laser beams are described. The fixtures consist of four thermocouples arranged in horizontal and vertical pairs and bonded to an aperture. An analysis is presented to show that more sensitivity is achieved by using a position fixture and an angle fixture with focusing at the angle fixture as opposed to simply passing the beam through two separated fixtures. A measurement of the angular sensitivity using a focused beam at the angle fixture indicates that angular changes on the order of 10 microradians can be detected.

ISSN:0034-6748    

DOI:10.1063/1.1136265

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

A contactless method for measuring the electrical conductivity &sgr; is described. In this method the conductivity is measured through the voltage induced in coils by the sample which rotates in a steady magnetic field. The dependence of the signal on sample geometry is studied and compared with experiment. The method is argued to be advantageous compared to the standard induction type techniques for contactless conductivity measurements.

ISSN:0034-6748    

DOI:10.1063/1.1136266

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

An x‐ray spectrometer based on the Johann bent‐crystal principle is described. An entrance slit system has been adopted which provides excellent protection of the diffracting crystal from metallic vapors. Such an arrangement also provides improved resolution and dispenses with the need for a thin film window between the x‐ray source and spectrometer tank. Resolution comparable to a two plane‐crystal instrument has been attained and systematic studies of the soft x‐ray emissions from liquid metals and alloys and metallic vapors undertaken.

ISSN:0034-6748    

DOI:10.1063/1.1136267

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

The fields and forces along the axis of an acoustic levitation device were measured and characterized. The device consisted of a St. Clair generator and reflector arranged in a single‐axis configuration. A significant (i.e., factor of four) enhancement in the levitation forces was obtained by using concave surfaces for the driver and reflector. For bodies of various sizes and geometries, the acoustic levitation force is roughly proportional to body volume until the characteristic ’’diameter’’ reaches ∼&lgr;/2(&lgr;=wavelength). In addition, the behavior of materials when in the liquid state was studied. Liquid drops were found to deform and generally rupture when a characteristic size was reached. The characteristic radius appears to depend on material parameters and is from 0.2–0.5 cm for most materials on the ground.

ISSN:0034-6748    

DOI:10.1063/1.1136268

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

A new tensile device that would permit theinsitufracture and Auger electron spectroscopy (AES) examination of samples under well‐controlled, measurable test condition, was developed. Using this device, a sample can be fractured in ultrahigh vacuum AES chamber at a temperature between room and melting point temperature of the sample and at any cross‐heat speed (that is, tensile speed) between 3 cm/min and 300 cm/min. A sample is resistance heated by passing a current and therefore, heating rate is changed at any rate. The maximum heating rate is about 1000°C/s. In this system, an air pressure piston as the tensile device, is used, and then the tensile speed is easy to control by changing the flow of oil from the air pressure piston to the air changer. And also the system is designed so that the mechanical shock is absorbed when a specimen is fractured. It is very easy how to set a sample in this fracture device and to fracture it. It is possible to set three samples at one time. We can apply this device to the study of many metal failures which are controlled by time and temperature dependent mechanisms, such as creep rupture, temper embrittlement, weldability, and hot workability. In this paper, the new fracture device and its application to nickel‐base superalloy are described.

ISSN:0034-6748    

DOI:10.1063/1.1136269

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

This paper describes a low light level, low resolution astronomical CCD (Charge Coupled Device) spectrometer useful in the spectral range 5000–9000 A˚. The instrument has a second CCD channel for direct broad‐band photometry of the region around the entrance slit. Both applications benefit from the high quantum efficiency, stability, dynamic range and linearity intrinsic to CCD’s. The detectors are cooled to 130 K which eliminates dark current and permits exposure times long enough to overcome the readout noise of ±30 electrons. At low spectral resolution the instrument has a signal‐to‐noise ratio which approaches the photon counting noise limit. The overall average quantum efficiency during observations is 1.3% between 5500 and 9000 A˚.

ISSN:0034-6748    

DOI:10.1063/1.1136270

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

Time‐domain reflectometry is used in a novel way to dynamically measure shock propagation in various media. The primary component in this measurement system is a digital time domain reflectometer, which uses local intelligence, a Motorola 6800 microprocessor, to make the unit adaptable and versatile. The recorder, its operating theory and its method of implementation are described and typical data are reviewed. Applications include nuclear explosion yield estimates, and explosive energy flow measurements.

ISSN:0034-6748    

DOI:10.1063/1.1136283

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

An optical detector that can measure the pulse width of a picosecond light pulse from a mode‐locked Nd‐glass laser has been developed. The detector was constructed with seven spatially separated CdS0.5Se0.5crystals which exhibited two‐photon conductivity when illuminated with 1.06 &mgr;m optical radiation. A seven‐channel peak detector and display system were used in conjunction with the two‐photon detector to record picosecond pulses on a single‐shot basis. For the laser used the measured correlation curve yielded a pulse width of 10 ps with a contrast ratio of 2.8:1.

ISSN:0034-6748    

DOI:10.1063/1.1136271

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

Cross sections for Oq+‐He single electron capture have been measured for 5⩽q⩽8 within the energy range 15 to 100 keV per amu. High energy positive ions were injected into an EN tandem Van de Graaff operated at a negative voltage, producing even higher energy for foil stripping to high charge states, followed by ion deceleration to reduce the ion energy by as much as a factor of 50.

ISSN:0034-6748    

DOI:10.1063/1.1136272

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

A highly versatile and cost effective general purpose laboratory interface system is described. Used with a mini or microcomputer, it accepts data and issues commands to many laboratory instruments having digital inputs and outputs. This system can be constructed by a novice in electronics at minimal expense. Details of the hardware construction and software device handling are given. Also described is an application of this system towards performing several common laboratory tasks: collecting both rapidly and slowly varying analog data, and simultaneously plotting the data. An implementation that is directly applicable to the LSI‐11 minicomputer is described in detail.

ISSN:0034-6748    

DOI:10.1063/1.1136273

出版商:AIP    

年代:1980

数据来源: AIP