摘要:

The theory of phase measurement by means of the interferometer using a filamentary spatial filter (IFSF) is extended to the case in which the source has finite width. Experimental results satisfactorily coincide with theoretically obtained characteristics. The examination of accuracy suggests that the error in &fgr;/2&pgr; can be easily restricted to within 0.01. It is hoped that the IFSF will improve efficiencies in the measurement of dispersive power of a fluid and the method of coincidence being used in the measurement of a distance between reflecting surfaces, because it can simultaneously measure phases in various wavelengths if a polychrometer is set in the rear of the image plane.

ISSN:0034-6748    

DOI:10.1063/1.1135918

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

An integrated control system for a pulsed ion cyclotron resonance (ICR) mass spectrometer has been designed, constructed, and put into operation. It utilizes a crystal clock oscillator to accurately control the delay and width of the various pulses necessary for pulsed ICR operation. A switched integrator, sample/hold postdetection system is also described which improves aquisition, display, and signal‐to‐noise characteristics of the detected ion signal obtained from a gated marginal oscillator detector.

ISSN:0034-6748    

DOI:10.1063/1.1135919

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

The least artifact‐laden fixation technique for examining colloidal suspensions, microemulsions, and other microstructured liquids in the electron microscope appears to be thermal fixation, i.e., ultrafast freezing of the liquid specimen. For rapid‐enough cooling and for observation in TEM/STEM a thin sample is needed. The need is met by trapping a thin layer (∼100 nm) of liquid between two polyimide films (∼40 nm thickness) mounted on copper grids and immersing the resulting sandwich in liquid nitrogen at its melting point. For liquids containing water, polyimides films are used since this polymer is far less susceptible to the electron beam damage observed for the commonly used polymer films such as Formvar and collodion in contact with ice. Transfer of the frozen sample into the microscope column without deleterious frost deposition and warming is accomplished with a new transfer module for the cooling stage of the JEOL JEM‐100CX microscope, which makes a true cold stage out of a device originally intended for cooling specimens inside the column. Sample results obtained with the new fast‐freeze, cold‐stage microscopy system are given.

ISSN:0034-6748    

DOI:10.1063/1.1135920

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

We have developed a new flow‐visualization technique based on the absorption of ultraviolet light by ozone. Ozone is an excellent tracer, because as a gas it has the same effective physical properties as air. Ozone strongly absorbs the principal line (253.7 nm) of a mercury lamp, &egr;=310 (atm cm)−1, whereI/Io=exp(‐&egr;cl) such that when an ozone‐traced flow passes between a mercury lamp and a fluorescent screen, a sharp, shadow‐like image of the ozone tracer is cast on the screen. Quantitative photometry can be carried out by replacing the screen with ultraviolet detectors that yield the path‐integrated column density of ozone in the flow. High‐speed quantitative point monitoring (10 Hz at 10 ppb O3) is possible with capillary probes and chemiluminescent analysis.

ISSN:0034-6748    

DOI:10.1063/1.1135921

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

A compact cw chemical HF/DF laser is described. The laser system consists of a microwave discharge using a surfatron to dissociate SF6molecules mixed with He, a reaction chamber engineered to provide a fast mixing of reacting atoms and molecules, and an optical resonator which includes a concave mirror and a blazed grating for line selection, both mounted on a rigid Invar frame. The laser oscillates on a single line single TEM00mode over manyPtransitions of HF and DF with a typical intensity fluctuation of 5% and a frequency jitter of about 30 MHz.

ISSN:0034-6748    

DOI:10.1063/1.1135922

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Two types of linear induction accelerator have been reported previously. In one, unidirectional voltage pulses are generated outside the accelerator and injected into the accelerator cavity modules, which contain ferromagnetic material to reduce energy losses in the form of currents induced, in parallel with the beam, in the cavity structure. In the other type, the accelerator cavity modules are themselves pulse‐forming lines with energy storage and switches; parallel current losses are made zero by the use of circuits that generate bidirectional acceleration waveforms with a zero voltage‐time integral. In a third type of design described here, the cavities are externally driven, and 100% efficient coupling of energy to the beam is obtained by designing the external pulse generators to produce bidirectional voltage waveforms with zero voltage‐time integral. A design for such a pulse generator is described that is itself one hundred percent efficient and which is well suited to existing pulse power techniques. Two accelerator cavity designs are described that can couple the pulse from such a generator to the beam; one of these designs provides voltage doubling. Comparison is made between the accelerating gradients that can be obtained with this and the preceding types of induction accelerator.

ISSN:0034-6748    

DOI:10.1063/1.1135905

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Techniques have been developed for measurement of the density of H−in a plasma by photodetachment. Photodetachment is detected by the increase in electron density with no change in positive ion density after a light pulse from a ruby laser. The authenticity of photodetachment signals can be assured by their comparison with known cross sections for photodetachment of H−. Interpretations of photodetachment data are less ambiguous than probe interpretations because photodetachment is not affected by the mass of positive ions and is not limited in usefulness by the Debye distance. Photodetachment measurements with time resolution and spatial resolution are straightforward.

ISSN:0034-6748    

DOI:10.1063/1.1135906

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Three collector electrodes have been located accurately on the focal plane of a parallel‐plate electrostatic energy analyzer to form an exit slit matched to a large inlet slit by the design magnification ratio. In bench tests with a nearly uniform, monoenergetic K+beam at 5 kV these collectors have been found to provide a scanning capability for measurement of the energy of such a large beam with sufficient precision, &Dgr;V/V∼±10−3, to resolve plasma potential in heavy ion probe diagnostic studies of magnetically confined plasmas. In such studies a wide entrance slit is needed because of low signal levels. The method provides enhanced resolution with greater facility than obtainable with a feedback approach used in prior investigations. A nearly triangular sharply peaked profile was observed on the center collector providing the desired resolution. Scans at various entrance angle settings have been made and beam size and peak location results compared with predictions based on the existing model for an ideal instrument.

ISSN:0034-6748    

DOI:10.1063/1.1135907

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Lexan coatings on polypropylene windows can eliminate the UV sensitivity of soft x‐ray proportional counters. A method is described for coating thin polypropylene films by dipping into and withdrawing from a volatile solution containing Lexan. The x‐ray absorption of a typical Lexan coating was only 7% at 44 A˚ which is small compared to that of 2 &mgr;m of polypropylene. The Lexan coatings are stable against vacuum cycling in an environment of UV irradiation. As an external, far‐UV filter up to wavelengths of 2400 A˚, Lexan‐coated polypropylene is an interesting alternative to metallic films, particularly when large area, high x‐ray transmission, and strength are important.

ISSN:0034-6748    

DOI:10.1063/1.1135908

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

An equation for the random noise of self‐scanned silicon photodiode arrays is developed which includes significant terms not previously considered. It is shown that, including these terms, the new 2.5‐mm‐high self‐scanned arrays are only slightly noisier than older arrays; but because of their much greater aperture, they can detect much smaller light fluxes than the older arrays even when used with simple, inexpensive amplifiers.

ISSN:0034-6748    

DOI:10.1063/1.1135909

出版商:AIP    

年代:1979

数据来源: AIP