摘要:

A spark gap switching system has been developed to coordinate the discharge of a 300 kJ capacitor bank with the high speed flow of helium in a shock tube driver. The trigger system includes a flow transducer, a pulse forming circuit, a high voltage spark generator, and four heavy duty spark gaps that can carry total peak currents greater than 1.5×106A. A glow gauge flow transducer sensitive to small gas density changes was used whose input power and signal output can withstand high voltage fluctuations. This switching system is of use with gasdynamic discharge devices requiring a minimum number of switches.

ISSN:0034-6748    

DOI:10.1063/1.1686511

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

An optical detection system is described which employs a commercial multichannel analyzer, augmented by a flat spectral response image intensifier and Kerr shutter, to provide time‐resolved, sensitive detection of plasmascattered ruby laser light. Operating characteristics are discussed and scattered spectra from CO2laser induced hydrogen plasma are shown.

ISSN:0034-6748    

DOI:10.1063/1.1686512

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

An apparatus is described which permits the determination of the mechanical permeability and the reflection coefficient of synthetic membranes at different hydrostatic mean pressures in the pressure range 1 up to 100 atm. Thus, it is possible to measure the volume flux across a membrane at pressures up to 100 atm using small pressure differences, &Dgr;P, across the membrane. Therefore, the linear relations of the thermodynamics of irreversible processes can be used for the evaluation of the transport properties at large mean pressures. Furthermore, it is also possible to perform measurements at large pressure and osmotic pressure differences where the usual linear relations of thermodynamics of irreversible processes may no longer apply. Some preliminary results obtained with asymmetric cellulose acetate membranes which were annealed at different temperatures are reported. These results show that the transport coefficients of the membranes depend on the mean pressure.

ISSN:0034-6748    

DOI:10.1063/1.1686513

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

The technique developed by Jamieson and Lawson for x‐ray diffraction at high pressure has been modified so that low‐Z materials can be studied under high pressure conditions to 12 GPa. A beryllium annulus replaces the commonly used boron annulus, allowing the use of Cu K&agr;or Fe K&agr;radiation, thus improving the accuracy ofd‐space determinations. The inclusion of a 4:1 methanol‐chanol mixture developed by Piermarini,et al.relieves pressure gradients and anisotropy, improving both the quality and range of compression data. Excellent compression results are obtained in the 0–1 GPa region where x‐ray techniques have formerly been inaccurate.

ISSN:0034-6748    

DOI:10.1063/1.1686514

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

A new type of particle counter, made sensitive by the application of a pulsed electric field, is described. The counter is comparatively slow, having a sensitive time in the 100 ns region and a recovery time of some 100 ms. Nevertheless, on account of its simplicity of construction, stability of operation and extemely low cost, the counter appears to be a useful tool, especially for complex experiments involving large detection systems. Examples of possible applications to particle physics experiments and to nuclear physics (ionization measurements) are given.

ISSN:0034-6748    

DOI:10.1063/1.1686515

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

Two instruments are described suited for recording thermoluminescent glow spectra respectively below and above room temperature. Their most remarkable property is the fact that the samples are kept under vacuum. Thermal insulation, thus, is good enough to allow samples to be placed only 15 mm from the light detector, even if they are heated up to 500 °C or cooled down to liquid N2temp. Consequently, the light collection efficiency turns out to be very high. These instruments are equipped with both analog and digital recorders, thus obtaining an accurate gathering of data.

ISSN:0034-6748    

DOI:10.1063/1.1686516

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

The interpolation fitting method using cubic splines to represent a Ge resistance thermometer characteristic is compared to the commonly used least‐squares fitting method. For a ``poorly behaved'' thermometer characteristic, the spline function is demonstrated to give considerably better interpolation accuracy. For a ``well‐behaved'' thermometer characteristic, the spline function gives comparable or slightly better accuracy. Also, it is shown that by choosing a more efficient interval spacing distribution for the calibration points, one may obtain this improved accuracy even with fewer calibration points.

ISSN:0034-6748    

DOI:10.1063/1.1686517

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

An ultrastable Mo¨ssbauer spectrometer using integrated circuits has been designed and tested. The system is designed to operate at velocities up to 100 cm/sec. Frequency stabilization of the order of 1 in 105is obtained using a crystal‐controlled oscillator. With the help of an automatic gain control circuit very good amplitude stability of the drive signal is obtained. The electronic system is designed to produce a sinusoidal velocity. The drive is capable of taking reasonably heavy loads so that the drive system can be kept at room temperature and the source is mounted at one end of a long stainless steel tube which goes into a helium Dewar.

ISSN:0034-6748    

DOI:10.1063/1.1686518

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

The redistribution of macromolecules dissolved in a paramagnetic solvent upon application of an inhomogeneous magnetic field has been observed. Using a special apparatus, this effect termed ``magnetosedimentation'' can be measured and used to determine the molecular weights of macromolecules.

ISSN:0034-6748    

DOI:10.1063/1.1686519

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

In order to investigate optical properties of liquid systems under high pressure two cells were constructed and tested. Special attention was given to the possibility of investigating equilibria or rates of reactions of corroding liquids.

ISSN:0034-6748    

DOI:10.1063/1.1686520

出版商:AIP    

年代:1974

数据来源: AIP