摘要:

A rocket payload able to perform a thorough and independent analysis of the He I 58.43340‐nm geocoronal and interplanetary emissions is presented. It includes a sun‐pointed resonant absorption spectrometer and a sky‐scanning resonant absorption photometer. Both incorporate a similar helium resonance cell of original design featuring a most flexible pressure scanning capability and an accurate pressure measuring device, so that scanning by wavelength bandpasses from 20 down to 1 pm can be achieved. A description of the design and calibration of the instrument is given, followed by an indication of its successful operation in flight.

ISSN:0034-6748    

DOI:10.1063/1.1136008

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

An interferometric technique designed to measure optical homogeneity in an electron‐beam‐pumped plasma is described and characterized. The system provides a two‐dimensional transient phase shift contour mapping of the excited region, at any time during or after the excitation pulse. The basic intrument is a 7‐cm‐field, 5‐m Mach‐Zehnder type interferometer coupled to a specially configured 2‐m e‐beam‐pumped sample chamber. By virture of ’’e‐beam partitioning,’’ absolute fringe shifts can be measured in a single shot. This relaxes the usually severe requirements on vibration isolation associated with systems of this size, and simplifies the overall mainframe construction. A short‐pulse XeF discharge laser, developed specifically for this application, is also described, and sample interferograms are presented for e‐beam‐pumped noble gas and noble gas–NF3mixtures. A ray calculus model is applied to the analytical interpretation of the interferograms produced by this technique. This model has general applicability to ray propagation in graded index media and is discussed in some detail.

ISSN:0034-6748    

DOI:10.1063/1.1136009

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Certain types of x‐ray experiments require very precise angular positioning of crystals in the vicinity of the Bragg reflection condition. A system applicable to some measurement of this type is described which achieves a long‐term angular stability of ∼10−7radians, coupled with a linear angular readout. This is achieved through a novel capacitance sensing system which provides angle measurement, together with the use of an auxilliary servo loop based on the Bragg condition to ensure long‐term overall angular stability.

ISSN:0034-6748    

DOI:10.1063/1.1136010

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

We present a method to infer the approximate species mixture of neutral beam sources which accelerate positive hydrogen ions. An idealized neutral beam is specified by the accelerating voltage, the neutralizer thickness (molecules of hydrogen per cm2), and the currents of extracted H+, H+2, and H+3. These currents define two independent ratios which lie within a narrow parameter region and which can be determined by two independent measurements downstream from the source. The two suitable parameters are (1) the ratio of neutral beam to total beam power; and (2) the ratio of hydrogen produced by the neutral beam in the target volume to the hydrogen produced by the total beam. We give experimental results from the 10×10‐cm2120‐KeV test stand at the Lawrence Berkeley Laboratory.

ISSN:0034-6748    

DOI:10.1063/1.1136011

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

An interface is described which permits high‐speed data transfer between a Biomation 8100 transient recorder and an Intel MDS‐800 microcomputer system equipped with an MDS‐501 DMA (direct memory access) channel controller. The interface is especially useful for data acquisition situations in which many successive traces must be recorded. For example, signal averaging can be performed within the microcomputer system.

ISSN:0034-6748    

DOI:10.1063/1.1136012

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

A powerful data acquisition and control system at a very low cost is presented. This is made possible by providing the interfacing hardware and supporting software to integrate the new and low‐cost consumer‐marketed ’’personal computers’’ into a useful and powerful data acquisition system. This system can be configured to the user’s need at any given time, simply by writing the appropriate software. In addition to its computing power, the system has been programmed for use as a transient digitizer–multichannel analyzer with a minimum of 12 &mgr;sec per channel, a data and curve fitter, a generalx‐yrecorder and averager, and a general purpose lab equipment controller. The system developed is, in many respects, at least as powerful as a DEC‐PDP 11/04 system—at a small fraction of the cost.

ISSN:0034-6748    

DOI:10.1063/1.1136013

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

A device for the measurement of concentration fluctuations in flowing gases which can be used to establish and control the degree of mixing is described. The design is based on an improved laser‐schlieren technique combined with photometric detection. The device operates on‐line and has high sensitivity and fast response. A quantitative sensitivity evaluation is made and checked experimentally. The device is used to characterize the performance of some simple mixing configurations. The detection limits for various gas mixtures are given.

ISSN:0034-6748    

DOI:10.1063/1.1135987

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

A SiC thin‐film thermistor for high‐temperature use has been developed by using rf‐sputtered SiC thin films. This thermistor can be used for industrial and consumer use within an operating temperature range of −100 to 450 °C. By using SiC thin films, the thermistor maintains high electrical stability. The resistance change is less than 3% after exposure to heat at 400 °C for 2000 h. In addition, the film growth technique made possible the production of a high‐accuracy thermistor, i.e., thermistor coefficient <±0.5%, thermistor resistance <±1.5%.

ISSN:0034-6748    

DOI:10.1063/1.1135988

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

An apparatus is described which extends the time range of the temperature‐jump technique at high pressures to the nanosecond region. A temperature increase of a few degrees can be obtained within approximately 50 ns by discharging a high‐voltage coaxial cable. Reactions are followed spectrophotometrically. Details of the temperature‐jump microcell and high‐pressure autoclave are presented. An application of this method is given for the reaction of phenol red with NH+4/NH3buffer at 1 and 2000 bars.

ISSN:0034-6748    

DOI:10.1063/1.1135989

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Microchannel plates (MCPs) are frequently employed with resistive anodes to detect charged particles or photons and yield analog signals from which event positions can be decoded. We discuss an anode geometry devised by C.W. Gear that offers theoretically distortionless encoding of Cartesian event positions into pulse charge ratios. Electron beam images taken with such an anode are shown, and confirm the usefulness of the approach.

ISSN:0034-6748    

DOI:10.1063/1.1135990

出版商:AIP    

年代:1979

数据来源: AIP