摘要:

Methods for high precision transient measurements using simple techniques for instrumentation and target alignment are described. Techniques are discussed in terms of application to a gas gun used to study the response of materials to dynamic loading. Results indicate that tilts of about 0.01° between impacting surfaces, projectile velocity measurements to about 0.1%, and time correlations to within 0.01 &mgr;sec are readily obtainable.

ISSN:0034-6748    

DOI:10.1063/1.1719944

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

We examine the problem of measuring with a probe the magnetic field in a plasma which is moving with respect to the probe. It is shown that integration with respect to time is, in general, not proper and we develop correct expressions for the case of a current conducting plasma produced by a strong ionizing shock wave in an electromagnetically driven shock tube. Use of the correct expressions is described for large area magnetic field probes employed in a coaxial electromagnetic shock tube. The results demonstrate the need for careful interpretation of data obtained from magnetic field probes used to measure magnetic fields in moving media.

ISSN:0034-6748    

DOI:10.1063/1.1719957

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

The design of a large Mach‐Zehnder interferometer which uses fused silica flats in aluminum mounts and piezo‐electric crystals for remote fine adjustment is discussed. In addition, an expedient method of alignment is given which allows the adjustment to fringes and to the white light fringe condition to be more conveniently and quickly accomplished.

ISSN:0034-6748    

DOI:10.1063/1.1719941

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

A large pressurized gas Cˇerenkov counter is described. The counter is designed to assist triggering on electrons in high energy counter‐spark chamber experiments. The requirement of large solid angle resulted in a counter of large dimensions and heavy construction. The results of tests made on the counter are presented. The tests indicate that the counter rejects pions very well and is roughly 50% efficient to electrons in the &Lgr;° beta‐decay spectrum (0–200 MeV).

ISSN:0034-6748    

DOI:10.1063/1.1719942

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

A reflection type microwave phase shifter is described which is similar to the units developed by Hardin, Downey, and Munushian. It employs the voltage‐variable capacitance of varactor diodes as the adjustable element. The ``pill type'' diodes tune their associated circuit through a resonance to produce phase shifts of over 90°. With proper adjustment of the tuning—a simple procedure—the output amplitude is made essentially constant. The use of two series diodes mounted back‐to‐back permits higher power operation, although the unit is essentially a low power device.

ISSN:0034-6748    

DOI:10.1063/1.1719943

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

A companion paper by Gardner and Hawke described a microwave phase shifter, with constant output, capable of rapid phase control by the bias voltage applied to varactor diodes. This paper describes the application of this device to measure phase shifts in a cw microwave system by a null method. If phase and amplitude variations are not too fast, standard oscilloscope components can provide most of the required circuitry. Examples are given, including the measurement of 0.003° phase shift at 9 Gc in a plasma experiment.

ISSN:0034-6748    

DOI:10.1063/1.1719945

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

Stable diamagnetic levitation of masses in excess of one gram has been accomplished in entirely passive systems using pyrolytic graphite and permanent magnets. Analytical and experimental data are given on two vertical thrust bearing assemblies. Extremely low frictional losses were determined from the rate of rotor deceleration in vacuum. Dissipation in a 4 cm diam rotor at 100 rpm was in the nanowatt range. Parametric studies are presented and possible applications discussed.

ISSN:0034-6748    

DOI:10.1063/1.1719946

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

A self‐contained easily expanded Monte Carlo program for the study of interactions in high energy physics is described. The program is capable of generating events and plotting results for a very wide class of reactions, including those governed by Lorentz invariant phase space and, also, those exhibiting resonances or other non‐trivial matrix elements. The performance of the basic program and the method of extending its scope are demonstrated in two examples showing the required input and resulting output.

ISSN:0034-6748    

DOI:10.1063/1.1719947

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

Three methods are described for enhancing specific oscillatory components of the magnetic field dependent attenuation coefficient of sound found in pure metals at liquid He temperatures. These oscillations are related to Fermi surface properties. Instrumentation suitable for these methods is described in detail. Some data taken with these techniques are shown. In addition, a description of the ultrasonic technique used is included.

ISSN:0034-6748    

DOI:10.1063/1.1719948

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

An electromagnetic balance for the measurement of fluid density at low temperature and elevated pressure is described. The balance is operated by balancing the changes in gravitational forces due to the buoyancy of a sphere immersed in the fluid against the electromagnetic force between a current carrying coil and a permanent magnet. The apparatus, which requires a relatively small amount of fluid, is capable of high precision and can be operated at any temperature below ambient and at pressures up to 80 atm.

ISSN:0034-6748    

DOI:10.1063/1.1719949

出版商:AIP    

年代:1966

数据来源: AIP