摘要:

A spectroscopic instrumentation system is described which forms one‐dimensional monochromatic EUV images of pulsed plasma sources. The system uses a small monochromator and a 22 anode microchannel plate detector to simultaneously view 22 chords of the plasma at the wavelength of a given impurity emission with 100 &mgr;s resolution. Brightness profiles are measured and stored in a minicomputer at up to 400 time points during a single discharge. If the discharge is cylindrically symmetric, this data can be Abel inverted directly to produce the volume emission rates and impurity density profiles during the discharge. The design, construction, and testing of the system are described, as well as its performance on the Alcator A tokamak.

ISSN:0034-6748    

DOI:10.1063/1.1136048

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

We describe a 430‐MHz SQUID magnetometer in which both the resonant frequency of the SQUID tank circuit and the input/output impedances of the following 4.2 K GaAs FET amplifier are varactor controlled. The intrinsic energy sensitivity of the magnetometer, in full flux lock from dc to 5 MHz, is 6.8×10−32J/Hz (≡4×10−6&Fgr;0/&sqrt;Hz flux sensitivity). The figure of merit is 2.1×10−31J/Hz.

ISSN:0034-6748    

DOI:10.1063/1.1136026

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

A precision analog simulator for a Josephson junction has been developed. This simulator is composed of several unit circuits and its sources of the error are tractable. The term corresponding to sin&fgr; is generated by an integrator with a resetting switch and a sinusoidal function generator. The time dependence of junction voltages and theI–Vcharacteristics are obtained for a current driven Josephson junction and compared with the analytical solutions for nonhysteretic case. The sources of the error are investigated in this simulator. In order to simulate quasiparticle conductance, an adjustable nonlinear resistance network was also constructed.

ISSN:0034-6748    

DOI:10.1063/1.1136045

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

A sensitive visible spectrometer has been designed to detect very small differences in the transmission or the reflection of two adjacent areas of a substrate. A probing light beam of variable wavelength is deflected between the two areas by a galvanometer‐type oscillating mirror in order to obtain a differential absorption or reflection. The absorption spectra of a dye incorporated in a Langmuir film, a monolayer of dye molecules covalently bonded to glass and molecules oriented in a stretched polyethylene film are presented as examples. The modification of the instrument to cover the near UV and IR regions is straightforward and will be discussed.

ISSN:0034-6748    

DOI:10.1063/1.1136049

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

A three terminal capacitance dilatometer for low temperatures is reported in which the expansivity of a sample is compared to that of silicon, a material of very small expansivity at low temperatures. The thermal expansion of a standard copper sample is measured down to 3 K and the results compared with other authors. Values for the linear thermal expansion coefficient of a pure NaF single crystal below 5 K are reported for the first time.

ISSN:0034-6748    

DOI:10.1063/1.1136050

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

Uniform, high‐quality sheets of CR‐39 (allyl diglycol carbonate) from ∼25 to ∼500 &mgr;m thick can easily be made by curing the initiated monomer between thin glass plates within a suitable gasket in a hot water bath or in an air oven.

ISSN:0034-6748    

DOI:10.1063/1.1136051

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

In this paper are described an irradiation calorimeter and data acquisition system used for simultaneous determinations of the rates of energy release and of resistivity recovery during anneals at low temperatures of irradiated metals. Both rates are measured on the same sample. the system provides efficient heat transfer from the specimen during irradiations and a good, reproducible degree of thermal isolation of the specimen during anneals. Necessary corrections to the raw data are discussed. The application of these measurements to determination of the energy released by interactions which immobilize self‐interstitial atoms is described and illustrated by data from the recovery between 12 and 35 K of platinum irradiated with 20.6‐MeV deuterons.

ISSN:0034-6748    

DOI:10.1063/1.1136052

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

We report the design of a low inductance park gap switch for Blumlein‐driven lasers which is highly reliable under conditions of high repetition rate and high average power. The reported spark gap has provided reproducible pulse waveforms without maintenance for 108shots in a Blumlein‐driven nitrogen laser. When operated with a nitrogen–SF6mixture in the laser tube, this laser provided peak powers in excess of 3 MW at 5‐Hz repetition rate and an average power of 0.5 W at 120‐Hz repetition rate.

ISSN:0034-6748    

DOI:10.1063/1.1136029

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

A wide‐angle, crossed‐beam laser Doppler scattering configuration is described. This configuration is optimized for measurement of electrophoretic mobility of blood cells. It is easy to align and maintain aligned and is stable against microphonic disturbance. The optimum scattering angle for blood cells is shown to be in the range of 25°–45°, a condition that is easy to implement with this configuration and within the geometrical constraints imposed by the use of narrow gap rectangular electrodes for applying an electric field.

ISSN:0034-6748    

DOI:10.1063/1.1136053

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

An automatically triggered digital integrator and the specific electronic circuits to measure the aspiration time was constructed and applied to flame atomic absorption spectrometry with discrete nebulization. The integrated signal was proportional to the absolute amount of the element in the sample solution injected. The ratio on the integrated signal to the aspiration time was proportional to the concentration of element in the sample solution irrespective of the volume injected. The reproducibility of the ratio method was 0.5%–1% for the sample volume ≳40 &mgr;l of 5 ppm Cu solution.

ISSN:0034-6748    

DOI:10.1063/1.1136030

出版商:AIP    

年代:1980

数据来源: AIP