摘要:

The construction and the operating details of a simple, field distortion, dielectric switch first used by Martin at A.W.R.E. and later extensively investigated by Dokopoulos at Ju¨lich are presented. The switch, triggered by a small, fast Marx circuit, holds off approximately 110 kV and switches 70 kV at 500 kA with an inductance of 12 nH. The switch produces multiple arcs through the switch package without meticulous switch package preparation, with pitted and scarred switch electrodes, and with a relatively slow trigger system. The dielectric switch is used in a fast theta pinch system and is designed to facilitate ease of operation, switch package preparation, and repeatable performance.

ISSN:0034-6748    

DOI:10.1063/1.1686501

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

This paper describes the construction and calibration of a complete optical system, built entirely within a standard helium cryostat, for making absolute measurements of radiation‐induced luminescence and optical absorption in the infrared range out to 25 &mgr;. Helium cooling the entire optical system reduced the thermal background radiation at the detector to approximately 1 × 109photons/cm2‐sec (&lgr;<25 &mgr;). Although helium Dewars for radiation effects have been described previously, to our knowledge no similar instrument for measuring radiation‐induced optical effects has been reported.

ISSN:0034-6748    

DOI:10.1063/1.1686502

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

The approximation of the Voigt line shape by the sum of a Gaussian and a Lorentzian of equal width is explored. The relative intensities of these two lines in the approximate function are related to the widths of the components of the Voigt function using nonlinear least‐squares fitting. The useful range of the approximation includes lines sharper than Lorentzian and flatter at the top than Gaussian.

ISSN:0034-6748    

DOI:10.1063/1.1686503

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

An automatic telescope dome controller which makes no use of computers has been developed and used. The device uses read‐only memories to derive the correct dome position from a digital readout of the telescope position. Interpolation is used to reduce the amount of memory required. The controller works equally well on large or small domes and is considerably less expensive and less complicated than existing automatic dome controllers.

ISSN:0034-6748    

DOI:10.1063/1.1686504

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

The disk‐type velocity selector is analyzed to obtain the effects of angular dispersion on velocity resolution and sideband elimination.

ISSN:0034-6748    

DOI:10.1063/1.1686505

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

6328 Å He&sngbnd;Ne laser structures, made from ultralow expansion materials, suspended in temperature‐ and pressure‐controlled chambers, have shown drift rates in excess of +5 MHz/day. The same structure, evacuated and used as passive Fabry‐Perot resonators, suspended in the previous now evacuated chambers, still show a drift rate of the order of +2 MHz/day. Computer simulated mirror model aging shows that relatively large changes of the dielectric constants of the mirror coatings are needed to explain the measured drift. We feel that the dimensional stability of the materials and the properties of the optical contacts used, as well as the behavior of the dielectric mirrors, have to be more carefully investigated.

ISSN:0034-6748    

DOI:10.1063/1.1686506

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

The conventional potential modulation technique employed in Auger electron spectroscopy measures the derivative of the electron energy distribution (d N / d E). A technique is described for recovering the energy distribution itself and the area under an Auger feature via electronic integration of the measured signal. This integration is conveniently performed using operational amplifier technology. This technique is demonstrated in a retarding field analyzer in the particular case of sulphur in ac(2×2) structure on a Ni(110) surface. The measured area under the sulphur Auger peak follows the square law dependence on oscillator modulation amplitude predicted by Houston. A quantitative comparison is made between the sulphur Auger signal strength, as measured by the area under the Auger peak, and that predicted by the calibration performed by Perdereau for this system. The sulphur (L2,3VV) Auger peak shape in theN(E) spectrum, as obtained by integration, was found to be in good agreement with that observed by other workers.

ISSN:0034-6748    

DOI:10.1063/1.1686507

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

An original thin optical cell for high pressure studies is described. The system of back pressure employed prevents the two windows from moving. In this way the only limitation in the control of thickness is due to elastic deformation of the two windows under pressure. The cell is particularly convenient for measurement of shifts of intense absorption bands. An example is given in the case of atomic lines of xenon in the region 1150–1500 Å, where thicknesses of less than 1 &mgr; are necessary.

ISSN:0034-6748    

DOI:10.1063/1.1686508

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

The transverse magnetoresistance of six 1/8‐W Allen‐Bradley carbon resistors with nominal room temperature resistances of 2.7, 3.9, and 5.6 &OHgr; was measured at various temperatures between 0.5 and 4.2 K in static magnetic fields up to 140 kG. Below 1.5 K, the magnetic field induced temperature errors of the resistors are small, less than 25%, and are very reproducible, i.e., ±0.8% in the case of the 2.7 &OHgr; units. Hence, these resistors are useful as low temperature thermometers in strong magnetic fields.

ISSN:0034-6748    

DOI:10.1063/1.1686509

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

We report the construction of a system to measure the circular dichroism of transient phenomena. The technique employs rapid modulation of the polarization of an analyzing beam, and consequently significant information can be obtained in a single run. The system is sensitive to changes in polarization strength of 2×10−5occurring in 1 msec. The particular system described has been constructed to follow transient structure changes in hemoglobin following laser photolysis of CO hemoglobin. The technique is quite general, however, and design details are presented which would be useful in any attempt to apply modulation spectroscopy to transient measurements.

ISSN:0034-6748    

DOI:10.1063/1.1686510

出版商:AIP    

年代:1974

数据来源: AIP