摘要:

The design and operation of an electrodynamically driven valve, which is employed to deliver rapidly a gas pulse (0.6 cc STP) with a sharp front to the annulus of a coaxial plasmoid source of small aspect ratio (2‐mm annulus at 2‐cm radius), is described. The spring loaded piston holds the plenum closed against pressures up to 2 atm. The piston is driven open by eddy currents induced by discharging a capacitor through a coil surrounding the plenum. A piston velocity of 5 cm/msec is achieved in less than 20 &mgr;sec and is maintained for 7 mm of travel. The arrival of a gas front (air) at the annulus was detected in 100 &mgr;sec after firing, employing hot‐wire anemometry. The subsequent axial position and velocity of this front in the source annulus were determined as functions of time and position, respectively. It was found that the initial axial velocity of the front exceeded the stagnation sound speed (though not the vacuum escape speed) and remained constant until the displacement thickness from wall friction reached the half‐annulus spacing.

ISSN:0034-6748    

DOI:10.1063/1.1717210

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

A system is described in which nuclear events characterized by three parameters are recorded in digital form on magnetic tape by the record station. The completed tape is then analyzed off‐line by the search station. Events of a typical experiment may consist of two pulse heights and a neutron time‐of‐flight, two pulse heights and an angle, or three coincident pulse heights. Each parameter is encoded by eight binary characters (bits) or 256 channels; thus, the number of different combinations is (256)3or approximately 17×106. Each event is recorded as three eight‐bit numbers across a 24‐track, 1¼‐in. magnetic tape. The tape is advanced in steps of 0.01 in. per event at low counting rates in order to conserve tape, and is moved continuously at high counting rates in order to achieve a recording rate of 170 events per second. During search of the recorded tape, restrictions are imposed on two parameters. If both are satisfied, the third variable of the corresponding event is tallied in one quadrant of a 1024‐word core memory. There are four such restriction gates, one for each memory quadrant. In a neutron experiment, for example, a single pass of a 2500‐ft tape with 3×106events lasts only 3⅓ min and produces four time‐of‐flight spectra, each with uniquely selected energy ranges of two coincident gamma rays as parameters. The four spectra may be viewed on a cathode‐ray tube or read out simultaneously by a typewriter, punched paper tape, and X‐Y recorder at a rate of 5 min per spectrum of 256 channels. For experiments with low coincident counting rates, this system provides an efficient method for accumulating and analyzing data. The entire system is made with solid‐state components, including 2100 transistors and 3300 diodes.

ISSN:0034-6748    

DOI:10.1063/1.1717211

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

A fast coincidence circuit using tunnel diodes is described. In ideal conditions, resolving times as low as 0.5 nsec have been measured. But in a practical case of beam particles crossing scintillation counters, a typical resolving time is ≈1.5 nsec. The same circuit can also be used as an anticoincidence whose total dead time can be as low as 5 nsec.

ISSN:0034-6748    

DOI:10.1063/1.1717212

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

A calorimeter for measuring heats of mixing for binary liquid systems has been designed and constructed. The calorimeter utilizes an internal bellows assembly to eliminate completely the vapor space within the calorimeter and is equipped with an internal platinum resistance thermometer for temperature measurement, an external solenoid assembly to activate the stirring instrument and an internally mounted calibration heater and radiation shield to minimize radiative heat losses. An evacuated outer chamber minimizes heat losses by conduction. Measurements of the heats of mixing of cyclohexane‐benzene, acetonitrile‐benzene, and bromoethane‐benzene yield a precision of 0.15%. The accuracy is estimated to be 0.25%.

ISSN:0034-6748    

DOI:10.1063/1.1717213

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

A technique has been devised for measuring the saturation magnetization and anisotropy constants of ferrites and garnets. It uses a tiny sample of the ferromagnetic material in a dc magnetic field. The sample is surrounded by a small radio‐frequency coil, which determines the frequency of an oscillating circuit. As the dc magnetic field is swept through a range of values, the frequency of the rf oscillator changes and becomes a measure of the magnetization. The technique makes possible a simple, versatile instrument that would be equal or superior in accuracy to any other technique now known. However, it is not suitable for metals because of their conductivity.

ISSN:0034-6748    

DOI:10.1063/1.1717214

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

Theoretical and computational results are presented to illustrate the behavior of single particle motion in spiral sector FFAG accelerators of small flutter factor when operated in the neighborhood of vertical‐radial coupling resonances. The theoretical analysis proceeds from the approximation in which the radial motion is determined without consideration of the vertical motion, and this solution is then inserted into the linearized equation for the vertical motion. The resulting generalized Hill equation is analyzed by a variational technique which yields both the bands of instability of the vertical motion and the exponential rate of growth within these zones. This mathematical analysis is confirmed by a computational study of the Hill equation used in the theoretical analysis. Extensive computational results are presented of the actual particle motion near coupling resonances for a choice of parameters characteristic of both full‐scale accelerators and models. Attention is concentrated on defining the regions of instability and determining the rate of vertical growth, both of which are seen to be in semiquantitative agreement with the theoretical analysis.

ISSN:0034-6748    

DOI:10.1063/1.1717215

出版商:AIP    

年代:1961

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1717217

出版商:AIP    

年代:1961

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1717219

出版商:AIP    

年代:1961

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1717221

出版商:AIP    

年代:1961

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1717222

出版商:AIP    

年代:1961

数据来源: AIP