摘要:

Specific impulse is an important parameter used to characterize the ballistic properties of a propellant. The calculation of this quantity has been a very tedious task, because a primary phase of this calculation involves the estimation of the composition of the products of combustion. This operation by standard techniques requires the simultaneous solution of ten equations containing ten unknown concentrations of reaction products for propellant systems composed of carbon, hydrogen, oxygen, and nitrogen. Iterative procedures have been found most efficient in solving these equations, but these are lengthy even when high speed calculating equipment is employed.An analog computer has been developed which simulates electrically the conditions of temperature, pressure, and composition of combustion products. These conditions are imposed as resistances in a series of interlocking Wheatstone bridges which, when balanced, produce the required resistances proportional to partial pressures. Mole fractions are obtained by dividing the partial pressures by the total pressure which also is produced as a proportional resistance by the computer.

ISSN:0034-6748    

DOI:10.1063/1.1745863

出版商:AIP    

年代:1951

数据来源: AIP

摘要:

A single‐channel analyzer has been built for measuring the pulse spectrum from proportional and scintillation counters; it counts the number of pulses whose heights lie betweenEandE+&Dgr;E. The interval &Dgr;Eor ``window width'' is constant within ±1.2 percent for all values ofEbetween zero and ninety volts. Curves are presented which show that the analyzer performs satisfactorily on the random distribution of pulse amplitudes obtained from counters.

ISSN:0034-6748    

DOI:10.1063/1.1745864

出版商:AIP    

年代:1951

数据来源: AIP

摘要:

A method of dilatometry using x‐ray illumination has been developed and applied to measurements of compressibility. Metal samples, 10 in. long and316in. in diameter, are subjected to pressures up to 10,000 atmospheres. Observations of the length of the compressed sample are made by causing x‐rays to cast a shadow on a photographic plate. The changes in length of the shadow are then determined with a comparator. This technique, which has been used to measure the compressibilities of aluminum, iron, and copper, is easily adaptable to remote measurements of any type involving changes of length, e.g., thermal expansion.

ISSN:0034-6748    

DOI:10.1063/1.1745865

出版商:AIP    

年代:1951

数据来源: AIP

摘要:

Measurements by Trevoy and the writer, to be published shortly elsewhere, have shown that the relative volatilities of mixtures of liquids increase surprisingly at low rates of distillations. A consequence is that organic liquids release volatiles into high vacuum apparatus more readily than would be deduced from measurements made at usual pressures of, say, 1–100 microns. The composition of condensate in an oil‐filled diffusion pump is found to be a function of position in the pump, the lightest constituents straying preferentially to the high vacuum end. As an example, Octoil contaminated with less than 1 percent of butyl phthalate in the last boiler of a 3‐stage pump was found to pass vapor through the high vacuum entrance as though the boiler had contained 27 percent butyl phthalate.To epitomize the situation, a vapor pump is a specialized form of still with two exits. The intention of the designer, expressed in the geometry of the pump, is to force the lighter molecules to one exit but molecular perversity causes them to wander to the other. The effect is probably unimportant except where the highest vacuums are required, though it does point to the desirability of thorough prepurification of pump oils; the task of fractionation, before and during use, is harder than we had supposed.

ISSN:0034-6748    

DOI:10.1063/1.1745866

出版商:AIP    

年代:1951

数据来源: AIP

摘要:

An instrument is described for plotting, automatically, magnetization‐temperature curves for ferromagnetic substances. The sample is placed on a torsion arm in an inhomogenous magnetic field, and the force to which it is subjected is opposed by a torque applied to a torsion wire by a reversible motor. The shaft of the motor is connected to a Beckmann Helipot, and the motion of the shaft is converted into a change in emf. which is recorded by a Leeds and Northrup Speedomax. The temperature of the sample is also controlled and recorded by the Speedomax. Data on the performance of the instrument are given and sample plots of thermomagnetic runs for Ni, Fe3O4, and Fe3C are shown.

ISSN:0034-6748    

DOI:10.1063/1.1745867

出版商:AIP    

年代:1951

数据来源: AIP

摘要:

A method is described which permits correlation between the separation of electrical contact points and the transient voltages occurring across the electrical contacts when a current is interrupted. The current from a photo‐tube, energized by light passing through an aperture‐slit system mounted on the same relay as the contact points, exhibits on a single‐triggered oscilloscope sweep the extent of contact separation on a time axis. This trace is superimposed on the same film frame as a subsequent transient voltage trace when the current is interrupted. The double exposure gives an accurate correlation between aperture and transient characteristic, inasmuch as the same sweep speed and sweep trigger are used for both traces and the sweep origin is extremely stable.

ISSN:0034-6748    

DOI:10.1063/1.1745868

出版商:AIP    

年代:1951

数据来源: AIP

摘要:

Design considerations involved in the development of low loss continuously variable resonant frequency crystal transducers are discussed. A description of such a system employing liquid mercury as a backing of continuously variable dimensions is presented. The important aspects; tight coupling of the crystal and mercury backing, and decoupling of the crystal and mercury from the supporting structure are considered in detail. Construction procedure on a unit to cover the frequency range 40 to 80 kc is indicated. Experimental results on the magnitude of the electrical input impedance as a function of frequency and mercury column length are given. A comparison of the variable resonant frequency unit used as a transducer with a series of fixed resonant frequency transducers is presented.

ISSN:0034-6748    

DOI:10.1063/1.1745869

出版商:AIP    

年代:1951

数据来源: AIP

摘要:

This paper describes a refractometer for measuring small changes in the dielectric constant or index of refraction of atmospheric air. The method employed is that of measuring the change in phase of a 9375 megacycle per second radio wave along a path approximately three feet long caused by a change in the average dielectric constant of the air over the path.The test path may be confined to a wave guide through which air is drawn, or it may be the space between two antenna systems. Because of the greater rigidity and the elimination of reflections, the wave guide system is able to measure short time changes in the index of refraction with an error of less than one part in a million. The antenna arrangement usually has somewhat larger error because of the flexibility of the supports and the external reflections.

ISSN:0034-6748    

DOI:10.1063/1.1745870

出版商:AIP    

年代:1951

数据来源: AIP

摘要:

Two designs of 15‐stage electron multiplier wherein focusing from one beryllium copper dynode to the next occurs in crossed electric and magnetic fields have been developed particularly for detection of weak beams or pulses of positive ions in magnetic fields. One, with dynodes ⅜ in. wide, is usable in fields between about 250 and 460 oersteds while the other, with dynodes ⅛ in. wide, is usable in fields between about 300 and 1100 oersteds. It appears likely that, by using still narrower dynodes, such multipliers can be constructed to operate in fields of several thousand oersteds. Advantages of these designs over previously described multipliers employing crossed fields are the use of about half the number of insulated plates and less tendency, because of uniformity of the electric field, for breakdown and noise, due to ion feedback, to occur. The uniformity of the electric field also allows quite reliable calculation of the spread in transit time. From this it is concluded that, with a modified collecting system, a multiplier could be built with a rise time between 10−11and 10−10sec, which is very probably less than could be obtained with a static multiplier.

ISSN:0034-6748    

DOI:10.1063/1.1745871

出版商:AIP    

年代:1951

数据来源: AIP

摘要:

An improved iron core magnet for general laboratory use, weighing two tons, has been designed and several units have been constructed. The design incorporates the desirable features of a number of earlier magnets and is engineered to give the optimum utility with minimum space and weight and with minimum attention by the operating personnel. A summary of test performance at 20 kw is given below. Operation at higher power levels will be described in Part II.11−in. diameter poles      5−in. gap10 kilogauss      2−in. gap17 kilogauss.534−in. diameter poles      2−in. gap23 kilogauss      1−in. gap30 kilogauss.1−in. diameter poles      1−in. gap32 kilogauss      12−in. gap37 kilogauss      14−in. gap42 kilogauss.

ISSN:0034-6748    

DOI:10.1063/1.1745872

出版商:AIP    

年代:1951

数据来源: AIP