摘要:

A high‐precision realization cryostat was developed for long stem type platinum resistance thermometers at the argon triple point. Six liters of argon gas (at room temperature) are sufficient for calibration and if ultrahigh purity grade is used one may expect the results to yield better than ±1 mK accuracy.

ISSN:0034-6748    

DOI:10.1063/1.1134567

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

A marginal oscillator (1–50 MHz) operating at relatively high, stable oscillation levels, with very low noise, is described. Phase‐sensitive detection of the real and imaginary parts of the surface impedance of metals or the nuclear susceptibility can be carried out from 0.5 Hz as a result of the low 1/fnoise. The noise is dominated by this 1/fnoise below 200 Hz, while at higher frequencies it is white and the oscillator has a noise factor of 1.15 or 0.6 dB.

ISSN:0034-6748    

DOI:10.1063/1.1134568

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

A digital detector for monitoring laser output energy that has been used successfully for accurate collection of lidar data is presented. The detector includes both an optical system to sample laser pulses and electronic circuitry to provide a digitized electronic output proportional to the energy in the sampled light pulses. Test results show that the detector system is capable of monitoring lidar relative output energy to within 1%.

ISSN:0034-6748    

DOI:10.1063/1.1134569

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

Based on principles which are outlined, an apparatus for alternating fields microelectrophoroesis is described. It uses a laternal orientation cell which is moved vertically at constant speed while a wave burst is applied to the cell. The resulting particles movements are photographed through dark‐field illumination and a microscope. The mobility is deduced from the track amplitudes on the photographs. An easy temperature correction is given. The main advantage of the A. C. microelectroesis method is a higher precision in the determination of the mobility distribution curve.

ISSN:0034-6748    

DOI:10.1063/1.1134574

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

Thermal expansion is determined by measuring interferometrically the relative displacement of two fibers attached to specimens. Coherent monochromatic light from a laser incident upon the two adjacent fibers produces a Fraunhofer fringe pattern. Relative displacement of the fibers can then be determined by monitoring the motion of the fringe pattern. The technique was applied to the measurement of thermal expansion of ceramics in air to 1150 °C and of graphites in vacuum to 1900 °C.

ISSN:0034-6748    

DOI:10.1063/1.1134575

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

A spectrometer is described which provides time resolution down to a few nanoseconds and broad‐band energy resolution in the range 5–200 keV along a single line of sight. The spectrometer consists of five channels arranged so that the x rays which are not absorbed in one plastic scintillator pass on to the next channel, but the scintillator emission is deflected onto a photomultiplier.

ISSN:0034-6748    

DOI:10.1063/1.1134576

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

The difficulties associated with the use of optical pyrometry for temperature measurement in an electron‐beam furnace are discussed. Light from the filaments producing the electron beam may be scattered into the optical pyrometer. A procedure has been developed that allows a determination of the required correction to the optical pyrometer reading which will take into account the scattered‐light effect and also the error introduced by the correction. The problems associated with the use of thermocouples at high voltage in an electron‐beam furnace are also evaluated.

ISSN:0034-6748    

DOI:10.1063/1.1134577

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

A simple modification of the sample holders for our superconducting magnetometer is described. It eliminates the holder contribution from the total signal.

ISSN:0034-6748    

DOI:10.1063/1.1134546

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

A novel sealed‐off low‐pressure quenching discharge gap capable of switching voltages up to 25 kV has been built. A recovery time of a few microseconds was measured, allowing switching rates in the 100 kHz range.

ISSN:0034-6748    

DOI:10.1063/1.1134547

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

A blanking circuit is described that is suitable for resistively heated samples. The Auger spectrum is blanked synchronously with the pulsed heating current. This arrangement allows the detection of undistorted Auger spectra from a fixed point on the specimen surface.

ISSN:0034-6748    

DOI:10.1063/1.1134548

出版商:AIP    

年代:1976

数据来源: AIP