摘要:

A continuous source of energetic hydrogen atoms has been developed for use in a plasma experiment. The mechanical design and some operating characteristics of the ion source are described, as well as the beam focusing and neutralizing system. An output of 65‐mA power equivalent of 20‐keV hydrogen atoms has been measured on a 2.0×6.3 cm target located 350 cm from the ion source.

ISSN:0034-6748    

DOI:10.1063/1.1718664

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

The use, in pulsed nuclear resonance experiments, of a voltage‐to‐frequency converter and an electronic counter to act as an integrator for the observed signals is described. Because measurements of this type are free of most subjective influences, they improve upon continued replication. Data are obtainable in a form which may easily be processed by a digital computer. Increased accuracy and sensitivity are the result. SampleT1determinations are presented. The relaxation in a sample showing a singleT1is followed to within one part in 104of equilibrium. Remarks are made concerning the design and use of a calibration equation capable of accounting for the behavior of a vacuum tube diode detector biased for linear operation.

ISSN:0034-6748    

DOI:10.1063/1.1718665

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

A time base is described which allows the spot of a cathode ray tube to be deflected at a rate proportional to the logarithm of the time. The circuit requires the use of two transistors, one of which serves as a conversion stage and the other as an amplifier stage. Two different sets of component values are given to cover a range of either two or three decades. The performance of the time base and its limitations in respect to temperature variations and supply voltage fluctuations are discussed.

ISSN:0034-6748    

DOI:10.1063/1.1718666

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

A friction measurement device has been developed which permits continuous measurement of static and kinetic coefficient of friction at ultrahigh vacuum. Sliding motion inside the vacuum chamber is accomplished by using a disk rotated by a zero‐leakage, direct‐drive rotary seal. The coefficient of friction is measured using a strain‐gauge system which is compatible with the ultrahigh vacuum test environment. An example of the type of results obtained with the device is given. The apparatus has been continuously operated at pressures in the 10−10Torr region.

ISSN:0034-6748    

DOI:10.1063/1.1718667

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

A temperature probe capable of reading temperature deviations of ±0.005°F or less at ambient temperatures has been developed using the large temperature coefficient of the reverse current of a Sylvania 1N77B photodiode. The photodiode case, a 0.072‐in.‐diam×0.80‐in.‐long glass cylinder, makes possible a small but very rugged probe assembly.

ISSN:0034-6748    

DOI:10.1063/1.1718668

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

An electronic regulator is described that is capable of controlling the temperature of a liquid‐helium bath within ±10 &mgr;deg for a few minutes and reducing long‐term drift to less than 40 &mgr;deg/h. With occasional adjustment, the temperature can be indefinitely maintained within ±10 &mgr;deg. The circuit is designed to be used with a resistance thermometer bridge previously described. The error signal from the bridge is displayed on a meter, so that the bridge can be balanced without use of an oscilloscope and the performance of the regulator can be continuously monitored.

ISSN:0034-6748    

DOI:10.1063/1.1718669

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

A two‐component null‐type microbalance has been developed to measure forces due to ion bombardment on a surface. The balance employs the principle of the attracted disk electrometer. The sensitivity can be adjusted by simply changing the location of the center of gravity. Measurements of a few micrograms of force in two perpendicular directions can be made simultaneously.

ISSN:0034-6748    

DOI:10.1063/1.1718670

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

Recent investigations of the broadening and shift of isotropic Raman lines of compressed hydrogen have demonstrated the effects of intermolecular forces on intramolecular motions. This paper describes two cells suitable for such experiments in the low to medium density range. The first is a cell for use at 85°K and 100 atm, which is similar in design to a conventional Raman source. The second cell, for use at room temperature and at pressures up to 1000 atm, utilizes the large compressive strength of glass and is an improved version of a cell reported previously. High resolution Raman spectra of theQ1branch of hydrogen have been obtained in the range 25 to 400 times standard density both at liquid air and room temperature.

ISSN:0034-6748    

DOI:10.1063/1.1718671

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

An electrodeless method for measuring the electrical conductivities of metallic and semiconductor melts at elevated temperatures is described. The transformer ``eddy current'' method, which was capable of measuring conductivities from one to greater than 10 000 (&OHgr;‐cm)−1, was used. The system was calibrated with Hg at 25°C and tested with Hg to 300°C and Bi to 550°C. The specific conductivities of various compositions of Bi&sngbnd;BiI3solutions were measured at 500°C and compared with those measured by an electrode method. The accuracy of the method decreased with decreasing conductivity.

ISSN:0034-6748    

DOI:10.1063/1.1718672

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

A simple method is described for the gain stabilization of a photomultiplier in which the stabilization system does not interfere with the fast pulse spectrum to be measured. The functioning principle consists in sending a low frequency (77 Hz) and very low intensity light pulse, which gives a modulation of the photomultiplier thermionic noise, on the photocathode together with the scintillation light. The modulation frequency is then selected on the anode by a special filter. The signal obtained in this way is used to trigger a feedback circuit, which makes the photomultiplier gain constant by suitably varying its voltage.

ISSN:0034-6748    

DOI:10.1063/1.1718673

出版商:AIP    

年代:1963

数据来源: AIP