摘要:

A novel diamond‐anvil cell is described which measures 19‐mm diameter by 28 mm long to fit the Oxford Instruments CF 1204 flow cryostat, while providing full axial and tilt adjustment of the diamonds. The drive mechanism provides for pressure changes while the cell is in the cryostat. The small dimensions are achieved because the drive force is not transmitted through the tilt mechanism, and by the Bowden cable technique used for the drive mechanism. This cell makes high pressure a readily portable technique that can be brought to many already existing experimental apparatuses.

ISSN:0034-6748    

DOI:10.1063/1.1139846

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

A conductivity‐type local void measurement system has been developed. The effects of the sensor tip geometry, the unbalance of the front‐end bridge, the comparator threshold level, and the mass fluxes on the response of the instrument have been studied. The system has been calibrated under air–water two‐phase flow conditions using the quick‐closing‐valve technique. Comparison of the void profiles obtained with the conductivity probe with those obtained using an optical probe confirms the applicability of this system for two‐phase (air–water) flows.

ISSN:0034-6748    

DOI:10.1063/1.1139847

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

An apparatus is described which permits periodic inversion of the electric field during field inversion gel electrophoresis (FIGE) studies. The device is used in conjunction with a standard electrophoresis power supply and the gel electrophoresis cell. Adjustment of cycle period from 0.01 to 99.99 s and forward migration percent from 1% to 99% are accommodated either by local programming or from a personal computer via a RS‐232C interface.

ISSN:0034-6748    

DOI:10.1063/1.1139848

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

The characteristics of twelve industrial‐grade and one precision platinum resistance thermometers for temperatures from 66 to 300 K and in magnetic fields up to 19 T are described. The results from the 13 models from nine suppliers are combined to produce mean values that may be used to correct any of those thermometers for effects of a magnetic field parallel to its long axis. The correctability error at 19 T is less than ±0.3% between 66 and 110 K and less than ±0.1% above 110 K. Magnetoresistance data for Rh–Fe and Au–Mn resistance thermometers are also presented.

ISSN:0034-6748    

DOI:10.1063/1.1139849

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

Unipolar and bipolar arbitrary waveform generators (AWGs) are described. Starting from a single 2‐ns‐wide pulse, a train of 2‐ns‐wide, variable amplitude pulses are formed by splitting the initial pulse into multiple, equal amplitude pulses and then delaying and attenuating each of these pulses separately. By choosing the proper attenuation (pulse amplitudes) and adding the train of pulses together, an arbitrary unipolar waveform can be constructed. With the addition of a second pulse generator of opposite polarity, an arbitrary bipolar waveform can be generated.

ISSN:0034-6748    

DOI:10.1063/1.1139850

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

We describe modifications made on a commercially available stepper motor to enable it to operate at liquid‐helium temperatures. The motor has a step angle of 6 deg and produces a torque of approximately 7×104dyn cm. When the motor is coupled to an 88:1 reduction gear, approximately 5×104ergs of heat are produced for each step.

ISSN:0034-6748    

DOI:10.1063/1.1139851

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

An improved double fluorescence detector for x‐ray absorption spectroscopy is described and compared to a standard filter‐slit detector.

ISSN:0034-6748    

DOI:10.1063/1.1139852

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

A simple method for the measurement of the refractive indices of parallel plate samples is described that uses the shift of the interference pattern when rotating the sample in one arm of a Mach–Zehnder interferometer. The theoretical fringe pattern shift is calculated and the accuracy of the method is derived. A typical accuracy of about 10−4can be achieved at low refractive indices. The method is especially useful when—because of other reasons—the samples are provided as plates or when prisms are difficult to fabricate.

ISSN:0034-6748    

DOI:10.1063/1.1139853

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

A description and working experience of an improved mechanical alignment system of a Spectra Physics 380 D ring dye laser is given.

ISSN:0034-6748    

DOI:10.1063/1.1140262

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

A simple beam chopper advantageously using the thermoelastic bending due to photothermal effect is reported. The mechanical vibration for chopping is generated due to the modulated irradiation from a laser diode so that the chopper is remotely operated.

ISSN:0034-6748    

DOI:10.1063/1.1139854

出版商:AIP    

年代:1988

数据来源: AIP