摘要:

An apparatus is described which allows studies to pressures of 100 kilobar and to temperatures of 0.03 K. A low temperature hydraulic press is incorporated with a dilution refrigerator to permit the continuous variation in pressure while at low temperature; thus, the entire pressure study of a material can be accomplished in one low temperature run. The sample is sensed magnetically using a SQUID magnetometer to detect changes in its magnetic moment. Operation of the system is described for measurements of the transition temperature of aluminum as a function of temperature and pressure.

ISSN:0034-6748    

DOI:10.1063/1.1134491

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

A pulsed power supply system with constant pulse energy has been developed to drive flashlamps in a 0.5–5 pulses per second Nd : glass laser. By using a stable, absolute reference voltage source to set the trigger level, the energy discharged through the flashlamps is kept constant despite pulsing frequency change, power line fluctuation, and minimum dc power supply regulation. The concept can be expanded or adapted to operate other similar systems.

ISSN:0034-6748    

DOI:10.1063/1.1134492

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

This paper describes an apparatus which can be used to determine bulk thermal expansion coefficients of liquids as a function of temperature and pressure up to 10 kilobar in a temperature range from −20° to 100 °C. The principle of the method consists in measuring the heat of compression by a step by step procedure. The apparatus is a Joule twin calorimeter which is composed of a high pressure vessel and a reference cylinder. Temperature differences between these two components can be detected at better than 10−5K by means of a gas thermometer, thus providing high sensitivity. Results are given for liquidn‐hexane and ethyl alcohol.

ISSN:0034-6748    

DOI:10.1063/1.1134493

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

An automatic temperature controller for a three‐phase, grid‐controlled induction furnace, which can maintain the oven temperature at the silicon melting point with a stability of ±0.4 °C for 2 h of operation, has been described.

ISSN:0034-6748    

DOI:10.1063/1.1134495

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

A simple model is developed to determine quantitative relations among operating parameters applicable to the design of ionization‐type smoke detectors. The model permits the adjustable parameters of operating current, radioisotope source intensity, and cell geometry to be specified for ambient pressure response and optimum sensitivity to smoke particulates. Specific ionization has been measured for two sources (3H and63Ni) as a function of pressure as required by the model. Experimental agreement with the model presented shows its validity for design evaluation of ionization cells for smoke detection and possibly other special applications with particulates.

ISSN:0034-6748    

DOI:10.1063/1.1134496

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

Electron bombardment of metallic silver is known to produce ’’transition radiation,’’ predominantly at 300–450 nm wavelengths. In reported measurements at 15–500 eV impact energies, transition radiation was used to diagnose the shape and time dependence of an rf modulated electron beam. It is suggested that this is a superior target, as opposed to phosphors or gases normally used, to determine instrumental time response functions and electron beam imaging.

ISSN:0034-6748    

DOI:10.1063/1.1134497

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

A modification of the ion source of a time‐of‐flight mass spectrometer is described which permits measurement of the angular spread of the ion beam leaving the ionization region. From these measurements, it is possible to obtain kinetic energy information for a specific, selected ionic species in a mass spectrum. In the modified ion source, ions leave the ionization region through a small, circular aperture, and then enter a region with a uniform accelerating electric field. Before they enter the drift tube for mass analysis, the ions must pass through a second small aperture, which is movable in a direction perpendicular to the flight tube of the mass spectrometer. The instrument has had all magnets removed. Analysis of the ion beam cross‐section profile yields values for excess kinetic energy and the relative abundances of ions which are formed from molecular states excited by electron impact. Typical results are presented.

ISSN:0034-6748    

DOI:10.1063/1.1134498

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

A channel plate phosphor system has been electrically pulsed in order to obtain time and space resolved images of a fast varying x‐ray source. Effective exposure times of about 3 nsec have been realized. Plasma focus x‐ray pictures obtained by this method are presented.

ISSN:0034-6748    

DOI:10.1063/1.1134499

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

A new method, the capillary method, is described here for fabricating ThC cathodes. Each cathode consists of W–Re tubing containing a W‐dendrite matrix filled with dense ThC–W eutectic. Hundreds of these cathodes have been used as sources for electron guns which require zero field emission capability of several A/cm2for thousands of hours. The effective work function of this cathode can be expressed as &fgr;=2.93+2.15×10−4T between 1750 and 2350 K.

ISSN:0034-6748    

DOI:10.1063/1.1134500

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

A fast‐discharge device that is volume scalable, capable of a high pulse‐repetition rate, and simple in construction is described. The device has two novel features: (1) it is assembled within a vacuum chamber so that atmospheric pressure is used to compress a parallel‐plate transmission line, and (2) it utilizes multiple transmission lines to provide increased lasing volume. This device is useful for generating laser action in N2, H2, and Ne, and for pumping many other self‐terminating lasers, such as metal vapor lasers and dimer lasers. Its discharge characteristics and its performance as a N2laser are discussed.

ISSN:0034-6748    

DOI:10.1063/1.1134501

出版商:AIP    

年代:1976

数据来源: AIP