摘要:

An analytical equation is derived for the error heat flow due to thermal imbalance between the hot plate and the guard in the case of an infinite strip. Finite element calculations show that the same equation can be used for circular plates with negligible error. The equation can also be extended to square plates if corner effects are neglected. By combining the present solution and a previous one by Woodside [Rev. Sci. Instrum.28, 1033 (1957)], an expression is derived for the effect of the distortion of heat‐flow lines near the gap even when thermal balance is obtained. The availability of this expression opens the possibility of using larger gaps than previously, to reduce thermal imbalance errors. The use of two‐material specimens (test material over hot plate, insulant over guard and gap) would lessen thermal imbalance errors, material requirements, and edge effects.

ISSN:0034-6748    

DOI:10.1063/1.1139127

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

A four‐probe technique for electrical and photoelectrical measurements in a gasketed diamond anvil cell is presented. The special anvil profile and the method for the gasket preparation used in these experiments are described. Insulation and continuity of the electrical leads are shown to be satisfactory at least up to 18 GPa. As an example we report photoconductivity measurements in GaAs beyond crossover, under pressure, between direct and indirect band‐gap configurations.

ISSN:0034-6748    

DOI:10.1063/1.1139129

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Some ideas as to what the important factors are that will produce a reliable indium O‐ring seal are discussed. Four novel indium seal designs which are based on these ideas are presented. Three of these seals have been incorporated in a Brillouin cell. They include a simple sapphire window seal, a filling line union, and a flange seal. All of them have withstood low temperatures down to 77 K and moderate pressures up to 177 bar. The fourth seal described is a Pyrex tube seal for a Raman cell.

ISSN:0034-6748    

DOI:10.1063/1.1139130

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

This paper describes a probing system to test a wafer immersed in liquid helium. This system is intended to improve the following three functions in comparison with conventional systems: (1) measurement of fast rise‐time electrical signals, (2) quick release of flux trapping with small loss of liquid helium, (3) facility in exchanging wafers. It was observed that signals with 2‐ns rise time could transmit through the system, the release of flux trapping could be achieved in several minutes with negligible helium loss using a cryoinsert with a closable hole at its bottom, and wafers could be exchanged similarly.

ISSN:0034-6748    

DOI:10.1063/1.1139131

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

A programmed multiple thin‐layer chromatography (TLC) developer of new design has been constructed and tested. It is controlled by a programmable delay timer and supported by other common solid‐state components. The system is dedicated to ‘‘Mode 1’’ operation and features a hard‐wired drying interval. Solvent removal is effected by a cold‐air blower and the elution chamber includes a solvent pump. This ensures rapid solvent vapor saturation of the TLC atmosphere after a drying cycle. The instrument is relatively inexpensive and can be constructed with facilities provided by many laboratories.

ISSN:0034-6748    

DOI:10.1063/1.1139132

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

A method is described which enables two computers to access a common memory area. One computer will be able to read and write to memory and will arbitrate over bus access. The other computer will be able to read memory only. Both computers will be able to select various RAM chips in the common memory area as required.

ISSN:0034-6748    

DOI:10.1063/1.1139133

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Modification of the pulse‐echo‐overlap equipment to make it compatible with any ordinary scope, which does not have an intensity modulation facility, is described.

ISSN:0034-6748    

DOI:10.1063/1.1139134

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

A method for stabilizing the optical output of pulsed light sources is described that uses a unique optical feedback loop. The method can assure an excellent stability of the optical output, and offers the advantage that it can be applied to a broad range of optical intensity. Stability tests of a pulsed light source using a GaP green light‐emitting diode (LED) stabilized by the proposed method are also described.

ISSN:0034-6748    

DOI:10.1063/1.1139216

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

This paper describes a convenient method which has been used for the measurement of small impulses (1–20 dyn s). An inductive displacement gauge was used to monitor displacement of a ballistic pendulum.

ISSN:0034-6748    

DOI:10.1063/1.1139135

出版商:AIP    

年代:1986

数据来源: AIP