摘要:

The problem of producing extremely high magnetic fields is briefly reviewed in the light of modern technique. The design, performance, and application of a pulsed‐field system capable of more than 750 000 gauss at room temperature is described. The coil comprises a suitably supported, machined, beryllium‐copper, helix having an inside diameter of316 in.and a length of about ½ in.; it is connected directly to a 2000 &mgr;f, 3 kv bank of surge capacitors by means of a triggered‐spark gap. The discharge is oscillatory with a half‐period of 120 &mgr;sec. Detailed design data and performance characteristics are presented for a large range of similarly constructed coils which afford increased volume and field uniformity at a sacrifice in field intensity. A coil providing transverse access to the field and one suitable for operation in liquid helium are also described. Characteristics of less durable coils constructed of a single strip of conductor are discussed. Brief comments on applications to a broad range of solid‐state experiments and some inherent limitations are presented. Finally, the production of modulated pulsed fields, unidirectional fields, and the feasibility of extending the pulse duration are discussed.

ISSN:0034-6748    

DOI:10.1063/1.1715727

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

This paper describes a wide‐band balun transformer which was developed for use with a 200‐Mc band‐width oscilloscope deflection amplifier. The balun has a band width extending from below 50 kc to above 500 Mc. Input impedance data and pulse responses are presented. One balun coil can be used alone as a passive wide‐band pulse inverter.

ISSN:0034-6748    

DOI:10.1063/1.1715728

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

The constructional details and method of operation of an optical diffusiometer are described. The apparatus makes use of a Mach‐Zehnder‐type interferometer, which has not previously been employed for the study of diffusion in liquid systems. The apparatus has been developed for the study of liquid systems whose components are volatile organic solvents. For this purpose a diffusion cell of novel design has been constructed. The diffusiometer has been checked using the system sucrose‐water at 25°C and values of the diffusion coefficient found over six determinations are within 0.2% of the reported value. With volatile liquids, the accuracy claimed is only 1%, although duplicates usually agreed to within 0.5%.

ISSN:0034-6748    

DOI:10.1063/1.1715729

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

A simple circuit for automatic plotting of probe curves and diode voltage‐current curves by means of commercialx‐ycurve plotters is described. Errors involved and corrections to be applied are discussed. The design of an electrolytic voltage divider for varying the probe voltage is given.

ISSN:0034-6748    

DOI:10.1063/1.1715730

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

An empirical relation is presented that describes a boundary between no vacuum sparking and possible vacuum sparking. Metal electrodes and rf or dc voltages are used. The criterion applies to a range of surface gradient, voltage, gap, and frequency that extends over several orders of magnitude. Current due to field emission is considered necessary for sparking, but—in addition—energetic ions are required to initiate a cascade process that increases the emitted currents to the point of sparking.

ISSN:0034-6748    

DOI:10.1063/1.1715731

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

A method is described in which a visible or infrared light beam is repeatedly reflected between a rotating and stationary mirror system. The resulting sweep speed is proportional to the number of such reflections. Light pulses of 4×10−8sec duration were measured. A considerable increase in the sweep speed appears feasible. Various applications of the system are mentioned.

ISSN:0034-6748    

DOI:10.1063/1.1715732

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

An apparatus is described for measuring linear compressibility of rods and tubes under hydrostatic pressures to 4000 kg/cm2and temperatures to 260°C. The measurements are made by means of a linear‐differential transformer located on the outside of the nonmagnetic high‐pressure container. The differential transformer makes it possible to determine the position of a small iron cylinder affixed to the sample. Compressibility of vitreous silica determined by this method was obtained as −&Dgr;V/V=p(26.43–0.0049t) ×10−7+p2(21.8–0.040t)×10−12; compressibility is expressed in relative volume change,pin kg/cm2andtin °C.

ISSN:0034-6748    

DOI:10.1063/1.1715733

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

A mass spectrometer ion source structure and its mode of operation are described by which the resolved ion current produced from a given gas concentration in the ionizing chamber can be made one to two orders of magnitude larger than is usually obtained in conventional mass spectrometer ion sources. This structure employs an ionizing chamber whose walls are electrically insulated from each other so they can operate at separate potentials which permit positive ions to be trapped in the ionizing electron beam. The resulting partial neutralization of the electronic space‐charge allows the use of a higher current density ionizing beam and also increases the effective ionizing volume from which a stable ion current can be extracted. Inherently this mode of operation produces more fragmentation species because it increases the probability of several successive electron impacts on each particle.

ISSN:0034-6748    

DOI:10.1063/1.1715734

出版商:AIP    

年代:1957

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1715736

出版商:AIP    

年代:1957

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1715737

出版商:AIP    

年代:1957

数据来源: AIP