摘要:

Measurements of the field distribution along the axis of a Nb3Sn superconducting pseudo‐Helmholtz coil, or ``split pair,'' are presented for various spacings between the two coils. The results agree well with the classically calculated field distribution and no current degradation effects that could be attributed to the multiple coil arrangement were observed. A maximum field of 58 kG was obtained in the region between the coils with the fields adding and a maximum field gradient of 26 kG/cm achieved with the coils powered in opposition.

ISSN:0034-6748    

DOI:10.1063/1.1719806

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

This paper reports a convenient method of absolute calibration for low homogeneity, superconducting solenoids for fields up to 85 kG. The method utilizes nuclear magnetic resonances of hydrogen and aluminum nuclei at rf frequencies up to 95 Mc. The NMR samples are in a liquid helium bath at the end of cables 1 m or more in length. Some measurements of hysteresis in an uncorrected superconducting solenoid are also reported.

ISSN:0034-6748    

DOI:10.1063/1.1719807

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

Construction parameters are given for coils to produce field gradients for use in NMR spin‐echo diffusion studies. The coils are shaped to give the greatest field gradient homogeneity in the region of the sample, taking into account image currents in the magnet pole faces. A circuit diagram of the current supply is given, including a transistor switch for pulsing the current.

ISSN:0034-6748    

DOI:10.1063/1.1719808

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

Chemical explosives are used to compress magnetic flux trapped within a metallic liner system. In this way, final magnetic fields from 0.5 MG in a volume of 40 cm3to 3.7 MG in 1.5 cm3have been produced and carefully measured. The conversion efficiency of explosive into electromagnetic energy has been as high as 10% in the most favorable cases. The different compression experiments, includingBzandB&phgr;configurations in various geometrical arrangements, are described in detail and their results analyzed and discussed.

ISSN:0034-6748    

DOI:10.1063/1.1719809

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

The design of flux concentrators to produce pulsed high magnetic fields is discussed with special attention to the problem of energy transfer efficiency. A flux concentrator is described which produces a peak field of 300 kG in a cylindrical volume 2.0 cm in diameter and 3.5 cm in length. Energy storage is by means of a 440 &mgr;F capacitor bank and the pulse length is 120 &mgr;sec.

ISSN:0034-6748    

DOI:10.1063/1.1719810

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

Magnet coils are investigated which can produce magnetic fields of 15–40 MA/m (200–500 kOe) during working times of the order of 0.1 sec. These fields are suited for measurements in highly conducting materials. The coils are precooled to 20°K or 77°K and the Joule heat is not removed during the pulse. In Sec. I the thermal limitations of this method are reviewed. Plots are given for the optimum dimensions and current densities for coils producing a specified field during a specified time, minimizing the necessary power supply. Details of a magnet constructed along these lines are given. The maximum field produced by this coil, 16 MA/m (200 kOe) during 0.3 sec, however, proved to be determined by mechanical instabilities. These problems are reviewed in Sec. II. Calculations of the Lorentz force and the internal stresses resulting from it were carried out taking the elastic and plastic properties of copper and insulation into account. It is shown theoretically that a magnet stable to 35 MA/m (440 kOe) can be built from hard drawn copper if a reinforcing steel cylinder is used at a certain radius inside the coil.

ISSN:0034-6748    

DOI:10.1063/1.1719811

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

A very simple display device is described that makes use of two independent time bases provided by some types of oscilloscopes. The device consists essentially of a diode gate driven from the oscilloscope by means of some rather simple associated circuitry. The ion beam signal is chopped, or sampled, peak after peak, smoothed by anRCfilter, and displayed by means of a pen recorder, a recording galvanometer, or another oscilloscope. Most of the statistical fluctuation in peak height is thus eliminated.

ISSN:0034-6748    

DOI:10.1063/1.1719812

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

A sample compartment is described which, with a standard x‐ray generator, allows routine observation of phosphor response to x rays. A unique feature is an automatic shutter which permits safe sample transfer while the x‐ray tube is excited. Some experimental results are provided.

ISSN:0034-6748    

DOI:10.1063/1.1719813

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

An instrument for measuring the internal friction of rod shaped specimens in the kilocycle frequency range is described. The specimens are excited into longitudinal resonance electrostatically and a frequency modulation technique is used to detect the resultant vibration. The linearity of the system is established by an absolute optical calibration technique and the accuracy of measurement is shown to be as follows. The internal friction is measured to an accuracy of ±1% up to a value of &dgr; (logarithmic decrement) of 6×10−3, with a background damping less than 5×10−6. The dynamic strain amplitude can be measured with an accuracy of ±2% over the working range of 5×10−8to 10−5.

ISSN:0034-6748    

DOI:10.1063/1.1719814

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

A platinum‐rhodium wound furnace built into a pressure vessel is described for investigation of phase equilibria at 1200–1700°C under oxygen pressures of up to 100 atm. The apparatus is designed for quenching small samples under pressure with a minimum of pressure seals to be broken for sample introduction and removal. Heat transfer at high pressure from the hot zone to the vessel wall limits the pressure‐temperature conditions obtainable within the power loading limits of the resistance wire.

ISSN:0034-6748    

DOI:10.1063/1.1719815

出版商:AIP    

年代:1965

数据来源: AIP